1. An epidermal protein of the RR-2 family of Oncorhynchus rhinoceros cuora, wherein the amino acid sequence of said epidermal protein comprises or consists of:

a) an amino acid sequence shown as SEQ ID NO. 1; or the like, or, alternatively,

b) a functional homologous sequence having at least 70% sequence identity to the amino acid sequence shown in SEQ ID No. 1; or

c) An amino acid sequence which is obtained by deleting, adding and replacing one or more amino acids in the amino acid sequence shown in SEQ ID NO.1 and has the same protein activity.

2. The epidermal protein of claim 1, wherein said amino acid sequence of b) and/or c) comprises the amino acid sequence of SEQ ID No. 2.

3. A nucleotide sequence encoding the epidermal protein of claim 1 or 2.

4. The epidermic protein-encoding nucleotide sequence of claim 3, wherein said nucleotide sequence comprises or consists of:

i) a nucleotide sequence shown as SEQ ID NO. 3; or the like, or, alternatively,

ii) a complementary, degenerate or homologous sequence (preferably over 70% homologous) to the nucleotide sequence shown in SEQ ID NO. 3; or the like, or, alternatively,

iii) a nucleotide sequence which hybridizes with the nucleotide sequence shown in SEQ ID NO.3 under the strict condition and can code the epidermal protein.

5. The epidermic protein-encoding nucleotide sequence of claim 4, wherein the nucleotide sequence of ii) and/or iii) comprises the nucleotide sequence set forth in SEQ ID No. 4;

preferably, the nucleotide sequence of ii) and/or iii) comprises the nucleotide sequence shown in SEQ ID NO. 5.

6. A primer for detecting or amplifying a nucleotide sequence according to any one of claims 3 to 5, said primer comprising an upstream primer and/or a downstream primer.

7. The primer according to claim 6, wherein the nucleotide sequence of the upstream primer P1 is shown as SEQ ID NO. 6; and/or the nucleotide sequence of the downstream primer P2 is shown as SEQ ID NO. 7;

preferably, the nucleotide sequence of the upstream primer P3 is shown as SEQ ID NO. 8; and/or the nucleotide sequence of the downstream primer P4 is shown as SEQ ID NO. 9.

8. Biological material or substance associated with the epidermal protein of claim 1 or 2, or the coding nucleotide sequence of any one of claims 3 to 5, or the primer of claim 6 or 7, selected from the group consisting of:

A1) the method comprises the following steps A biological material containing the epidermal protein;

A2) the method comprises the following steps An expression cassette containing the encoding nucleotide;

A3) the method comprises the following steps A recombinant vector containing the coding nucleotide;

A4) the method comprises the following steps A recombinant vector comprising the expression cassette of a 2);

A5) the method comprises the following steps A recombinant microorganism containing the coding nucleotide;

A6) the method comprises the following steps A recombinant microorganism comprising the expression cassette of a 2);

A7) the method comprises the following steps A recombinant microorganism comprising a3) said recombinant vector;

A8) the method comprises the following steps A recombinant microorganism comprising a4) said recombinant vector;

A9) the method comprises the following steps Reagents containing the primers;

A10) a kit comprising a9) or the primer.

9. The biological material or substance of claim 8, wherein the recombinant vector comprises at least one of pET28a, pcdna3.1, pUC18, pBR322, pUC19, pGEX2T, pESC-Ura; more preferably pET28 a;

preferably, the recombinant microorganism comprises at least one of escherichia coli, pseudomonas, bacillus, yeast cells; more preferably E.coli BL21(DE 3).

10. A method for preparing the epidermal protein of claim 1 or 2, comprising the steps of:

introducing the nucleotide sequence of any one of claims 3-5, or the related biological material or substance of claim 8 into a host cell for expression to obtain the epidermal protein.

Background

Insects, the oldest organisms in the world, are now in the form of enormous amounts of strong security, the powerful adaptability and the special physical structure of which the epidermal structure is one of. The main components of insect epidermis are chitin and epidermal proteins. Chitin is polymerized from N-acetyl glucosamine, and has clear structure. The difference between the chain length and acetylation degree of chitin molecules of different types of epidermis is small, so that the variation of the types and the number of epidermal protein genes is an important factor influencing the epidermal structure and the mechanical properties thereof, and therefore, the epidermal protein is considered as an important structural protein of insects all the time. According to the sequence characteristics of insect epidermal proteins, the insect epidermal proteins are divided into 12 families, such as CPR (with Rebers & Riddiford conserved motifs), CPF (with a highly conserved region 44 amino acids long), CPFL (CPF like), Tweedle (with 4 conserved regions), CPAPI (with 1 ChBD2 chitin binding domain), CPAP3 (with 3 ChtBD2 chitin binding domains), CPG (with many short glycine repeats), CPLC (a class of proteins with low complex sequences) and Apidermin. Among them, the CRR family can be divided into 3 subfamilies, namely RR-1, where soft cuticle is mainly present, RR-2, where hard cuticle is mainly present, and RR-3, which are not much studied at present.

At present, in the research of insect epidermal protein, the research of model insects is more intensive, for example, japanese scholars randomly select cDNA from a silkworm wing primordium pre-pupation cDNA library for sequence determination, and identify 10 different epidermal protein genes. The YasuyukiArakane group, national university of south Korea, has targeted Chihua-mie and studied the function of epidermal proteins with high abundance in the coleopteran. Nohr et al found that the inner and outer epidermis protein compositions of migratory locust have obvious difference by using a two-dimensional electrophoresis technique. Andersen et al analyzed and identified 8 endothelial proteins from desert locust by MALDI-MS technique; a plurality of post-ecdysis proteins (inner epidermis synthesis period) are identified from locusta migratoria and cockroaches, and the research lays a foundation for the research on the action mechanism of the epidermal proteins in the insect metamorphosis development and epidermal formation process.

However, the current studies on insect epidermal proteins mainly aim at the aspects of differences between the inner and outer epidermis, identification, classification, extraction and the like of epidermal proteins, and the studies on biological functions are less.

Disclosure of Invention

The invention provides a Rhinoceros dichotomu RR-2 family epidermal protein, the amino acid sequence of which comprises or consists of the following sequence:

a) an amino acid sequence shown as SEQ ID NO. 1; or the like, or, alternatively,

b) a functional homologous sequence having at least 70% sequence identity to the amino acid sequence shown in SEQ ID No. 1; or

c) An amino acid sequence which is obtained by deleting, adding and replacing one or more amino acids in the amino acid sequence shown in SEQ ID NO.1 and has the same protein activity.

The horn of the golden tortoise is specialized by the epidermis, is a natural defense attack weapon and has obvious fracture toughness resistance and deformation rigidity resistance. The invention takes the Odona bicolor as a research object, discovers a novel RR-2 subfamily protein gene from the horn of the Odona bicolor, is self-defined and named as Td14144, and successfully obtains the recombinant protein of the gene (namely the epidermal protein of the Odona bicolor, which is also named as Td14144 in the invention). Td14144 epidermal protein has a property of liquid-liquid phase separation at normal temperature, and is capable of binding different types of chitin.

In one embodiment of the present invention, the amino acid sequence of the scarab epidermidis protein Td14144 is shown in SEQ ID No. 1: GLIPAAPALSLGHAALAAPALSLGHAVGPALSLSHTALAAPAISLGHAVAAPALSLGHAAVAAPAYGIGHGLGLGYGLGHGAIAAPALVKAAPAIVKAAPAVDYVAYPKYEFNYGVSDAHTGDQKTQHEIRDGDVVKGSYSLHEADGTVRTVHYEADDHNGFNAVVTRSGHAAHPATPIAVAAPAKTIIAAPAIAHAAPVFAHAGPALAYGGLYGYKG, the sequence length is 218 amino acids.

In one embodiment of the invention, the amino acid sequence of the scarabs epidermidis protein Td14144 is a functional homologous sequence having at least 70% sequence identity with the amino acid sequence shown in SEQ ID No. 1. The functional homologous sequence includes, but is not limited to, an amino acid sequence having about 70% or more, 72% or more, 74% or more, 76% or more, 78% or more, 80% or more, 82% or more, 84% or more, 85% or more, 88% or more, 90% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.5% or more, 99.9% or more identity to the amino acids shown in SEQ ID No. 1.

In one embodiment of the present invention, the amino acid sequence of the epidermic protein Td14144 of rhinoceros scarab is an amino acid sequence in which one or more (for example, 1 to 10, specifically, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acids are added, deleted, or substituted in the amino acid sequence shown in SEQ ID No.1 and has the same activity. For example, an amino acid sequence obtained by attaching a tag to the N-terminus and/or C-terminus of the amino acid sequence shown in SEQ ID NO. 1.

In one embodiment of the present invention, the amino acid sequence of the scarab epidermidis protein Td14144 is shown in SEQ ID No. 2:MFAKVFAIATFVATAQAGLIPAAPALSLGHAALAAPALSLGHAVGPALSLSHTALAAPAISLGHAVAAPALSLGHAAVAAPAYGIGHGLGLGYGLGHGAIAAPALVKAAPAIVKAAPAVDYVAYPKYEFNYGVSDAHTGDQKTQHEIRDGDVVKGSYSLHEADGTVRTVHYEADDHNGFNAVVTRSGHAAHPATPIAVAAPAKTIIAAPAIAHAAPVFAHAGPALAYGGLYGYKG, (signal peptide region underlined), the sequence is 235 amino acids long, and the N-terminus contains a 17 amino acid long signal peptide region.

In a second aspect, the invention provides a nucleotide sequence encoding the scarab epiderm protein Td 14144.

Further, the nucleotide sequence encoding the epidermoid Td14144 comprises or consists of:

i) a nucleotide sequence shown as SEQ ID NO. 3; or the like, or, alternatively,

ii) a complementary, degenerate or homologous sequence of the nucleotide sequence shown in SEQ ID NO. 3; or the like, or, alternatively,

iii) nucleosides which hybridize under stringent conditions to the nucleotide sequence indicated in SEQ ID NO.3 and are capable of coding for said epidermal protein

And (3) sequence.

In one embodiment of the invention, the nucleotide sequence of the rhinoceros scarab epiderm Td14144 is shown in SEQ ID NO. 3: GGCCTAATACCAGCTGCACCAGCTCTTTCCCTTGGACATGCCGCCCTAGCAGCTCCAGCACTATCGCTTGGTCATGCTGTTGGACCGGCTCTTTCGCTTAGCCATACAGCGTTAGCCGCCCCAGCTATCTCTCTAGGTCATGCAGTTGCTGCCCCAGCTCTTTCTCTTGGTCACGCCGCTGTCGCTGCTCCAGCTTACGGAATAGGTCATGGATTGGGATTGGGGTATGGACTTGGACACGGAGCCATCGCCGCACCAGCTCTTGTTAAAGCCGCACCTGCTATCGTAAAGGCAGCTCCAGCTGTTGATTATGTGGCATATCCGAAATACGAATTCAACTACGGAGTCTCCGATGCCCACACCGGCGATCAAAAAACCCAACATGAAATCCGCGATGGTGACGTAGTAAAAGGCTCATACTCCCTCCACGAAGCCGATGGCACCGTCCGTACCGTCCACTACGAAGCCGATGATCATAACGGCTTCAACGCAGTTGTAACCAGATCAGGACACGCTGCGCATCCTGCTACACCAATTGCCGTCGCGGCTCCCGCCAAAACCATCATTGCAGCTCCAGCTATAGCGCACGCAGCCCCAGTCTTCGCGCACGCTGGTCCAGCGTTGGCGTACGGAGGATTGTACGGTTACAAGGGTTAG, the sequence length is 657 bases, corresponding to coding the scarab epiderm protein with the amino acid shown in SEQ ID NO. 1.

In one embodiment of the invention, the nucleotide sequence encoding epidermic protein Td14144 of the rhinoceros crenulata is a complementary sequence formed by the nucleotide sequence shown in SEQ ID NO.3 according to the base complementary pairing principle, and the complementary sequence can be an incomplete complementary sequence or a complete complementary sequence with the function of encoding epidermic protein Td 14144.

In one embodiment of the invention, the nucleotide sequence encoding the epidermoid Td14144 is degenerate as a nucleotide sequence to the nucleotide sequence shown in SEQ ID No. 3. The degenerate sequence is that after one or more nucleotide sequences of SEQ ID No.3 are changed, the positions of the changed nucleotide sequences are unchanged corresponding to the types of coded amino acids, and the coding function and the expression level of the nucleotide sequences are not influenced.

In one embodiment of the invention, the nucleotide sequence encoding the epidermoid Td14144 is a homologous sequence of the nucleotide sequence shown in SEQ ID No. 3. The homologous nucleotide sequence comprises a mutant gene, an allele or a derivative which is generated by adding and/or substituting and/or deleting one or more nucleotides in the nucleotide sequence shown in SEQ ID NO.3 and can code the same activity of the epidermal protein Td 14144.

More preferably, the homologous sequence is about 70% or more, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, a polynucleotide that is 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, 99.7% or more, 99.8% or more, or 99.9% or more identical and has a function of encoding epidermoid Td 14144.

In one embodiment of the invention, the nucleotide sequence encoding the epidermoid Td14144 is a nucleotide sequence which hybridizes under stringent conditions to the nucleotide sequence of SEQ ID No.3 and is capable of encoding the epidermoid Td 14144. Illustratively, the "stringent conditions" refer to conditions under which a probe will hybridize to a detectable degree to its target sequence over to other sequences (e.g., at least 2 times background). Stringent conditions are sequence dependent and will vary from one environment to another. By controlling the stringency of the hybridization and/or washing conditions, target sequences can be identified that are 100% complementary to the probe. Alternatively, stringency conditions can be adjusted to allow some sequence mismatches so that a lower degree of identity is detected.

Further, the nucleotide sequence of the rhinoceros scarab epiderm protein Td14144 is shown in SEQ ID NO. 4: ATGTTCGCTAAGGTTTTCGCAATCGCTACATTTGTAGCCACCGCACAAGCTGGCCTAATACCAGCTGCACCAGCTCTTTCCCTTGGACATGCCGCCCTAGCAGCTCCAGCACTATCGCTTGGTCATGCTGTTGGACCGGCTCTTTCGCTTAGCCATACAGCGTTAGCCGCCCCAGCTATCTCTCTAGGTCATGCAGTTGCTGCCCCAGCTCTTTCTCTTGGTCACGCCGCTGTCGCTGCTCCAGCTTACGGAATAGGTCATGGATTGGGATTGGGGTATGGACTTGGACACGGAGCCATCGCCGCACCAGCTCTTGTTAAAGCCGCACCTGCTATCGTAAAGGCAGCTCCAGCTGTTGATTATGTGGCATATCCGAAATACGAATTCAACTACGGAGTCTCCGATGCCCACACCGGCGATCAAAAAACCCAACATGAAATCCGCGATGGTGACGTAGTAAAAGGCTCATACTCCCTCCACGAAGCCGATGGCACCGTCCGTACCGTCCACTACGAAGCCGATGATCATAACGGCTTCAACGCAGTTGTAACCAGATCAGGACACGCTGCGCATCCTGCTACACCAATTGCCGTCGCGGCTCCCGCCAAAACCATCATTGCAGCTCCAGCTATAGCGCACGCAGCCCCAGTCTTCGCGCACGCTGGTCCAGCGTTGGCGTACGGAGGATTGTACGGTTACAAGGGTTAG, the sequence length is 708 bases, corresponding to coding the scarab epiderm protein with the amino acid shown in SEQ ID NO. 2.

Further, the nucleotide sequence of the rhinoceros scarab epiderm protein Td14144 is shown in SEQ ID NO. 5:

(wherein, the T7 promoter is underlined in a single solid line, the T7 terminator is underlined in a dotted line, and the cleavage site is underlined in a double solid line) and has a sequence length of 919 bases.

In a third aspect of the present invention, there is provided a primer for detecting or amplifying the nucleotide sequence encoding the coat protein Td14144 of Rhinoceros crenata.

In a preferred embodiment of the invention, the primers comprise an upstream cloning primer P1 and/or a downstream cloning primer P2; wherein the nucleotide sequence of the upstream cloning primer P1 is shown as SEQ ID NO. 6: 5'-ATGTTCGCTAAGGTTTTCGCAATCG-3', respectively; the nucleotide sequence of the downstream cloning primer P2 is shown as SEQ ID NO. 7: 5'-CTAACCCTTGTAACCGTACAATCCTCCG-3' are provided.

In a preferred embodiment of the invention, the primers comprise an upstream junction primer P3 and/or a downstream junction primer P4; wherein the nucleotide sequence of the upstream connecting primer P3 is shown as SEQ ID NO. 8: 5'-AGGAGATATACCATGGGCTTAATACCAGCTGCACCAG-3', respectively; the nucleotide sequence of the downstream connecting primer P4 is shown as SEQ ID NO. 9: 5'-GACGGAGCTCGAATTCCTAACCCTTGTAACCGTACAATCCTCC-3' are provided.

In the invention, the application of the scarab beetle epidermal protein Td14144 comprises the following aspects: (1) the polypeptide of the amino acid sequence of the epidermal protein Td14144 or at least part of the amino acid sequence may still have biological activity or even new biological activity after removal or substitution of certain amino acids, or may have improved yield or optimized protein kinetics or other properties aimed at; (2) relates to the biosynthesis of the epidermal protein Td14144 and related truncations, mutants, polypeptides; (3) relates to the application of epidermal protein Td14144 in developing relevant biological materials.

The application of the coding nucleotide sequence comprises the following aspects: (1) the nucleotide sequence or at least part of the nucleotide sequence provided by the invention is modified or mutated, and the modification or mutation way comprises insertion, deletion, Polymerase Chain Reaction (PCR), error-prone PCR, reconnection of different sequences, directed evolution of different parts of the sequence or homologous sequences with other sources, or mutagenesis by chemical reagents and the like. (2) The nucleotide sequence provided by the invention or at least partial nucleotide sequence cloning gene is expressed in an exogenous host through a suitable expression system to obtain corresponding epidermal protein or other higher biological activity or yield. (3) The nucleotide sequence or at least partial nucleotide sequence gene or gene cluster provided by the invention can construct recombinant plasmid through genetic recombination to obtain a novel biosynthesis pathway, and can also obtain the novel biosynthesis pathway through insertion, replacement, deletion or inactivation.

In a fourth aspect, the present invention provides a biological material or substance related to said scarab epidermidis protein Td14144, or said encoding nucleotide sequence, or said primer, selected from the group consisting of:

A1) the method comprises the following steps A biological material containing said epidermal protein Td 14144;

A2) the method comprises the following steps An expression cassette containing the encoding nucleotide;

A3) the method comprises the following steps A recombinant vector containing the coding nucleotide;

A4) the method comprises the following steps A recombinant vector comprising the expression cassette of a 2);

A5) the method comprises the following steps A recombinant microorganism containing the coding nucleotide;

A6) the method comprises the following steps A recombinant microorganism comprising the expression cassette of a 2);

A7) the method comprises the following steps A recombinant microorganism comprising a3) said recombinant vector;

A8) the method comprises the following steps A recombinant microorganism comprising a4) said recombinant vector;

A9) the method comprises the following steps Reagents containing the primers;

A10) a kit comprising a9) or the primer.

Further, the type of the recombinant vector is not particularly limited, and an appropriate vector can be selected as needed. For example, vectors include, but are not limited to, pET28a, pcdna3.1, pUC18, pBR322, pUC19, pGEX2T, or pESC-Ura, preferably pET28 a.

Further, the recombinant microorganism includes but is not limited to at least one of Escherichia coli, Pseudomonas, Bacillus, and yeast cell. Coli BL21(DE3) is preferred.

In a fifth aspect, the present invention provides a method for preparing the epidermal protein, comprising the steps of:

introducing the nucleotide sequence encoding the epidermal protein Td14144 or the related biological material or substance (e.g., the expression cassette, the recombinant vector) into a host cell for expression to obtain the epidermal protein.

In a preferred embodiment of the present invention, the method for preparing the epidermal protein Td14144 comprises the steps of:

the method comprises the following steps: synthesizing a nucleotide sequence shown in a sequence table SEQ ID NO. 4;

step two: constructing a recombinant vector and a corresponding recombinant expression gene engineering bacterium according to the nucleotide sequence of the step one;

step three: and (3) performing prokaryotic expression on the recombinant gene engineering bacteria obtained in the step two, and purifying the obtained protein to obtain the epidermal protein Td 14144.

The invention adopts the technical scheme and has the following beneficial effects:

(1) the invention provides a newly discovered RR-2 subfamily epidermal protein of the rhinoceros refer to, provides a new gene resource for researching the RR-2 subfamily epidermal protein, and is helpful for clarifying the structure and physiological function of insect epidermis and the role played by the insect in the insect development process.

(2) The scarab beetle epidermal protein Td14144 provided by the invention has the characteristic of liquid-liquid phase separation, can be combined with different types of chitin, and can be used for developing a bionic material with excellent performances such as light weight, strong toughness, strong fracture resistance, hydrophobicity and the like.

Drawings

FIG. 1 is a graph showing the results of gene cloning of the epiderminin Td14144 in example 1. Wherein: m is the standard nucleic acid molecular weight MarkerDL2000, and lane 1 is the Td14144 epidermal protein gene of about 708 bp.

FIG. 2 shows the expression and purification of the epidermoid Td14144 in example 1. In the figure: m is a standard protein molecular weight Marker; lane 1 is the imidazole concentration of the elution buffer 20 mmol/L; lane 2 shows the imidazole concentration of the elution buffer at 90mmol/L, and lane 3 shows the purified epidermal protein Td14144 eluted at an imidazole concentration of the elution buffer at 250 mmol/L; lane 4 is a western blot validation of epidermal protein Td 14144.

FIG. 3 shows the selective binding of the epidermoid Td14144 to different types of chitin in example 2. Wherein M is a standard protein molecular weight Marker; t represents all proteins; e represents a chitin-binding protein; f represents an unbound protein.

FIG. 4 shows the temperature transition (LCST) of the epidermoid Td14144 in example 3. Wherein: the left side is a solution of the epidermal protein Td14144 at 4 ℃ and the right side is a solution of the epidermal protein Td14144 at room temperature (25 ℃).

FIG. 5 is a graph showing the results of optical microscope observation of the epidermoid Td14144 under the condition of room temperature (25 ℃) in example 3.

Detailed Description

Custom "Td 14144" may refer to the RR-2 subfamily epidermal protein of the CPR family of rhinoceros operculea, or the epidermal protein gene, or the nucleotide sequence encoding an epidermal protein, as specifically referred to herein in conjunction with contextual judgment.

In the present invention, the term "nucleotide" is used in its ordinary sense as understood by those skilled in the art.

In the present invention, the term "amino acid" refers to any amino acid (both standard and non-standard amino acids), including but not limited to alpha-amino acids, beta-amino acids, gamma-amino acids, and delta-amino acids. Examples of suitable amino acids include, but are not limited to, alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, tyrosine, arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

In the present invention, the "stringent conditions" may be any of low stringency conditions, medium stringency conditions or high stringency conditions. "Low stringency conditions" include, for example, 5 XSSC, 5 XDenhardt's solution, 0.5% SDS, 50% formamide, and 32 ℃. "Medium stringent conditions" include, for example, 5 XSSC, 5 XDenhardt's solution, 0.5% SDS, 50% formamide, and 42 ℃. "high stringency conditions" include, for example, 5 XSSC, 5 XDenhardt's solution, 0.5% SDS, 50% formamide, and 50 ℃ conditions. Under these conditions, it is expected that DNA having high homology can be obtained efficiently as the temperature is increased. The factors affecting the stringency of hybridization may be various factors such as temperature, probe concentration, probe length, ionic strength, time, salt concentration, etc., and those skilled in the art can appropriately select these factors to realize the same stringency.

Unless defined otherwise, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The invention is described in detail below with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

Example 1 cloning and expression purification of Td14144 Gene

Synthesis of a nucleotide sequence encoding Td14144

1. Extraction of total RNA of golden sea turtle

Total RNA in Crotalaria dichotoma was extracted using TRIzol reagent in this experiment.

Experiment preparation work:

(1) cleaning the mortar, the pestle and the medicine spoon, and drying in an oven.

(2) Completely wrapping the mortar, pestle and spoon with aluminum foil paper, and dry-heat sterilizing in an electric oven at 180 deg.C for 4 hr, and naturally cooling.

(3) The reagent required by the experiment is cooled in advance, so that the low-temperature state in the process is ensured.

(4) Dissecting and cleaning Rhinoceros dichotoma newly emerged imago, quickly freezing with liquid nitrogen for 2-3min, and storing in-80 deg.C refrigerator. And (3) experimental operation:

(1) a set of mortar, pestle and spoons was pre-cooled sufficiently with liquid nitrogen in a clean bench.

(2) A prepared sample of the golden cuora trifoliata is added into a mortar. And adding liquid nitrogen to start grinding (the sample is under the protection of liquid nitrogen at any time during grinding), and when the sample is in a uniform powder state, finishing grinding.

(3) 1mL of Trizol reagent was added to a 1.5mL centrifuge tube, a flat spoon (about 100mg) of the sample was added using a pre-cooled spatula, shaken and mixed well, and allowed to stand at room temperature for 5 min.

(4) And (3) sucking 200 mu L of acidic chloroform by using a gun head, adding into the centrifuge tube in the step (3), fully shaking and uniformly mixing on an oscillator, and standing at room temperature for 5 min. The mixture was centrifuged again for 15min at 4 ℃ and 12000rpm, and 200. mu.L of the supernatant was aspirated by a pipette tip and added to a new 1.5mL centrifuge tube.

(5) And (3) sucking 200 mu L of acidic phenol chloroform by using a gun head, adding into the centrifuge tube in the step (4), fully shaking and uniformly mixing on an oscillator, and standing at room temperature for 5 min. The mixture was centrifuged again for 20min at 4 ℃ and 12000rpm, 150. mu.L of the supernatant was aspirated by a pipette tip and added to a new 1.5mL centrifuge tube.

(6) 500. mu.L of isopropanol was pipetted with a pipette tip and added to the centrifuge tube in (5) and the reverse was repeated 10 times. The centrifuge tube was frozen in a freezer at-20 ℃ to facilitate RNA precipitation.

(7) Centrifuge the tube from (6) for 20min at 4 ℃ and 12000 rpm. The supernatant was decanted off.

(8) With RNase-free H₂Preparing 1ml of 75% ethanol by using O and absolute ethanol, washing and precipitating, centrifuging for 5min at 4 ℃, 12000rpm, and pouring out the supernatant.

(9) The above experiment was repeated once.

(10) Standing at room temperature for 20min, adding 50 μ L RNase-free H₂And O, fully dissolving the precipitate.

(11) mu.L of the above product was taken in a PCR tube, 2. mu.L of which was used for Nanoview to measure the product concentration, and the remaining 3. mu.L was subjected to 1% agarose gel electrophoresis to evaluate the RNA quality. The rest RNA was stored in a refrigerator at-80 ℃.

2. Reverse transcription of the first strand of the synthetic cDNA (complementary deoxyribonucleic acid);

first, add to a 0.2mL centrifuge tube: mu.L of total RNA obtained in step 1, 1. mu.L of oligo (dT) primer (50. mu.M), 5. mu.L of RNase free ddH₂O, mixing and centrifuging for a short time, immediately placing on ice for more than 10min after bathing at 65 ℃ for 5min, centrifuging for a short time for a few seconds to ensure that the mixed solution is completely gathered at the bottom of the centrifuge tube, and adding 4 mu L of 5 XPrime Script Buffer, 0.5 mu L of RNase Inhibitor (40U/. mu.L), 1 mu L of PrimeScip II RTase (200U/. mu.L) and 4.5 mu L of LRNase-free Water. After mixing, the reaction was performed at 42 ℃ for 1 hour to synthesize cDNA by reverse transcription, and then the enzyme was inactivated at 95 ℃ for 5min, and the resulting cDNA solution was used for PCR amplification.

Amplification of epidermal protein Gene Td14144 by PCR reaction

(1) And (3) designing a primer according to the transcriptome sequencing gene sequence of the Rhinoceros dichotoma by taking the cDNA obtained in the step 2 as a template, and amplifying the cDNA sequence of the epidermal protein Td14144 gene.

Upstream primer P1: 5'-ATGTTCGCTAAGGTTTTCGCAATCG-3' (SEQ ID NO. 6);

the downstream primer P2: 5'-CTAACCCTTGTAACCGTACAATCCTCCG-3' (SEQ ID NO. 7).

And (3) PCR reaction system: 1 μ L cDNA template, 25 μ L2 × Premix Taq^TM1.5. mu.L of primer P1, 1.5. mu.L of primer P2, complementary ddH₂O to the total reaction system was 50. mu.L.

PCR reaction procedure: firstly, 94 ℃ for 10 s; ② 55 ℃ and 30 s; ③ 72 ℃ for 1 min; 30 cycles. Storing at 4 ℃.

(2) After the PCR experiment was terminated, 5. mu.L of the PCR product was collected and subjected to electrophoresis on a 1% agarose gel to verify the size of the DNA fragment. And (3) taking pictures by using a gel imaging system, observing results, screening strips with the same gene fragment size as a predicted value, and recovering PCR amplification products according to the agarose gel DNA recovery kit specification to obtain a nucleotide sequence shown in a synthetic sequence table SEQ ID NO. 4.

(3) After the recovery of the to-be-cut gel is finished, connecting the recovered DNA fragment to a T-load by using a kit, transforming escherichia coli competence DH5 alpha, and selecting a monoclonal for sequencing.

Second, constructing recombinant vector and recombinant expression gene engineering bacteria

The vector of the recombinant expression vector is a pET-28a prokaryotic expression vector; the recombinant expression engineering strain is Escherichia coli BL21(DE 3).

(1) And determining the position of a segmentation point of a signal peptide coding sequence through signal peptide prediction, designing a connecting primer according to a fragment behind a signal peptide by taking a T-vector as a template to carry out second-step PCR amplification, introducing homologous regions of about 20bp which are consistent with an expression vector sequence at two ends of the sequence, and introducing restriction enzyme cutting sites of restriction enzymes at two ends.

Ligation primer P3:

5’-AGGAGATATACCATGGGCTTAATACCAGCTGCACCAG-3’(SEQ ID NO.8)；

ligation primer P4:

5’-GACGGAGCTCGAATTCCTAACCCTTGTAACCGTACAATCCTCC-3’(SEQ ID NO.9).

PCR reaction system (50. mu.L), 1. mu.L of T-vector template, 1.5. mu.L of each of 2 XPrime STAR HS 25. mu. L, pET28a-14144F/R, and adding ddH2O to 50. mu.L of total reaction system.

Reaction conditions are as follows: 30 cycles of 94 ℃ for 10s,55 ℃ for 30s, and 72 ℃ for 1 min; storing at 4 ℃.

(2) The expression vector plasmid pET28a was double digested with restriction enzymes Ncol and EcoRI, and the fragment carrying the gene of interest was ligated to the cleaved vector by In-Fusion homologous recombination to form the complete ligation product pET28a-Td 14144.

(3) Uniformly mixing the recombinant expression vector ligation product with an escherichia coli competent cell (e.coli BL21), placing in an ice bath for 30min, performing water bath at 42 ℃ for 45s, taking out, and performing ice bath again for 2 min; then adding 900 mul LB liquid culture medium, oscillating and culturing for 1h at 37 ℃ and 200 rpm; 200 μ L of the bacterial liquid was uniformly spread on LB solid medium (containing 50mg/L kanamycin) and cultured overnight at 37 ℃ to obtain a colony.

(4) Carrying out bacteria detection PCR on the clone colonies, wherein the reaction conditions are as follows: 30 cycles of 94 ℃ for 10s,55 ℃ for 30s, and 72 ℃ for 1 min; storing at 4 ℃. After the reaction was terminated, the PCR product was subjected to electrophoresis using 1% agarose gel to examine the size, and the results of the electrophoresis are shown in FIG. 1.

(5) The single colony of the correct size of the gene fragment was selected and inoculated into 10ml LB (containing kanamycin) culture solution at 37 ℃ overnight with shaking at 200rpm, and the plasmid was extracted with a plasmid extraction kit and sequenced. And obtaining the recombinant engineering strain with correct sequencing.

Third, Td14144 protein expression and purification

(1) The expression plasmid pET28a-Td14144 after the sequencing verification is transformed into an escherichia coli expression strain BL21(DE3), the strain is expanded and cultured after being activated until the OD600 in the logarithmic growth phase is 0.5-0.6, an inducer IPTG is added to lead the final concentration to be 0.1mmol/L, and the bacteria are collected by centrifugation after being induced for 5 hours at 37 ℃. Centrifuging a small amount of bacterial liquid at room temperature of 12000g for 1min, collecting thalli, and removing supernatant; the cells were resuspended in disruption buffer (20mM Tris, 500mM NaCl, pH7.4) and sonicated, the supernatant was collected by centrifugation and subjected to SDS-PAGE and western blot detection.

(2) Inoculating the detected pET28a-Td14144/BL21 recombinant engineering strain into 10mL of LB (containing 50mg/L of kanamycin) liquid culture medium, shaking at 37 ℃ and 200rpm overnight, inoculating the strain into 1000mL of LB (containing 50mg/L of kanamycin) liquid culture medium according to the proportion of 1:100, culturing at 37 ℃ until the light absorption value OD600 is 0.5-0.6, adding IPTG (isopropyl thiogalactoside) to induce mass expression of recombinant protein, and centrifuging 10000g for 10min after induction is finished to collect the strain;

(3) adding a crushing buffer solution (20mM Tris, 500mM NaCl, pH7.4) for heavy suspension, crushing bacteria by using a high-pressure homogenizing crusher, centrifuging to remove cell slice precipitate, and passing supernatant through a nickel ion affinity chromatography column; td14144 protein was washed (20mM Tris, 500mM NaCl, 20mM imidazole; 20mM Tris, 500mM NaCl, 90mM imidazole, pH7.4) and eluted (20mM Tris, 500mM NaCl, 250mM imidazole, pH7.4) using an AKTA protein purifier. And performing polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting (western blot) detection to obtain purified recombinant epidermal protein Td14144, wherein the amino acid sequence of the recombinant epidermal protein is shown in SEQ ID NO. 1.

Example 2 detection of the ability of Td14144 protein to bind to chitin

Purpose of the experiment: detection of the binding Capacity of Epimectin Td14144 to different types of chitin

The experimental process comprises the following steps: alpha-chitin (alpha-chitin), beta-chitin (beta-chitin), colloidal chitin (colloidal chitin) and chitosan (chitosan)4 types of chitin are selected to be combined with the recombinant expressed epidermal protein Td14144 for in vitro combination experiments.

The method comprises the following specific operations: the purified recombinant expression protein was dialyzed into a binding buffer (20mM Tris, pH 8.0). A200. mu.L reaction system was constructed so that the final concentration of protein was 0.5mg/mL and the final concentration of chitin was 2 mg/mL. The reaction was carried out at room temperature (25 ℃) and the proteins and different types of chitin were mixed in a 2mL centrifuge tube by continuous inversion for 4 h. After the reaction, the reaction mixture was centrifuged at 12000r/min for 10min, and the supernatant was collected as chitin-unbound protein. 1mL of binding buffer (20mM Tris, pH8.0) was added to the pellet, the pellet was resuspended and mixed by inversion, and then 13000g was centrifuged for 5min, and the supernatant was discarded, thereby completing one washing of the pellet. Repeating for 3-5 times. And finally adding 50 mu L of electrophoresis sample buffer solution into the sediment to boil for 5min, centrifuging for 5min at 13000g, removing the sediment, and collecting the supernatant as the combined chitin protein. Finally, each collected fraction was detected using polyacrylamide gel electrophoresis.

And (4) experimental conclusion: the results of the test of the binding ability of the recombinant protein Td14144 to chitin are shown in FIG. 3, and the recombinant protein Td14144 can bind to 4 types of chitin, including alpha-chitin, beta-chitin, chitosan and colloidal chitin.

Example 3 detection of liquid-liquid phase separation Properties of Td14144 protein

The experimental process comprises the following steps: first, macroscopic observations were made at different temperatures of Td14144 protein solution to produce Liquid-Liquid phase separation (LLPS). Visual inspection of the protein solution revealed that Td14144 protein was clear and transparent at 4 deg.C, and the protein solution gradually changed from clear to turbid as the temperature increased to room temperature (25 deg.C), as shown in FIG. 4.

The protein solution was observed at room temperature with an optical microscope, and the protein Td14144 was found to be aggregated (Cco acervate), and the result is shown in FIG. 5, wherein the heterogeneous round balls in the protein solution are aggregates.

The agglomerates have flow deformability and can be fused with each other to form larger agglomerates; and the aggregate formation and disappearance are reversible, the aggregate formation is carried out when the temperature is increased to room temperature, the aggregate disappears when the temperature is reduced to 4 ℃, and the protein solution is recovered to be in a clear state.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and the like that are within the spirit and principle of the present invention are included in the present invention.

Sequence listing

<110> institute of agricultural genomics of Chinese academy of agricultural sciences

<120> Allotia bicolor RR-2 family epidermal protein, coding nucleotide sequence and application thereof

<141> 2021-05-26

<160> 9

<170> SIPOSequenceListing 1.0

<210> 1

<211> 218

<212> PRT

<213> Unknown

<400> 1

Gly Leu Ile Pro Ala Ala Pro Ala Leu Ser Leu Gly His Ala Ala Leu

1 5 10 15

Ala Ala Pro Ala Leu Ser Leu Gly His Ala Val Gly Pro Ala Leu Ser

20 25 30

Leu Ser His Thr Ala Leu Ala Ala Pro Ala Ile Ser Leu Gly His Ala

35 40 45

Val Ala Ala Pro Ala Leu Ser Leu Gly His Ala Ala Val Ala Ala Pro

50 55 60

Ala Tyr Gly Ile Gly His Gly Leu Gly Leu Gly Tyr Gly Leu Gly His

65 70 75 80

Gly Ala Ile Ala Ala Pro Ala Leu Val Lys Ala Ala Pro Ala Ile Val

85 90 95

Lys Ala Ala Pro Ala Val Asp Tyr Val Ala Tyr Pro Lys Tyr Glu Phe

100 105 110

Asn Tyr Gly Val Ser Asp Ala His Thr Gly Asp Gln Lys Thr Gln His

115 120 125

Glu Ile Arg Asp Gly Asp Val Val Lys Gly Ser Tyr Ser Leu His Glu

130 135 140

Ala Asp Gly Thr Val Arg Thr Val His Tyr Glu Ala Asp Asp His Asn

145 150 155 160

Gly Phe Asn Ala Val Val Thr Arg Ser Gly His Ala Ala His Pro Ala

165 170 175

Thr Pro Ile Ala Val Ala Ala Pro Ala Lys Thr Ile Ile Ala Ala Pro

180 185 190

Ala Ile Ala His Ala Ala Pro Val Phe Ala His Ala Gly Pro Ala Leu

195 200 205

Ala Tyr Gly Gly Leu Tyr Gly Tyr Lys Gly

210 215

<210> 2

<211> 235

<212> PRT

<213> Unknown

<400> 2

Met Phe Ala Lys Val Phe Ala Ile Ala Thr Phe Val Ala Thr Ala Gln

1 5 10 15

Ala Gly Leu Ile Pro Ala Ala Pro Ala Leu Ser Leu Gly His Ala Ala

20 25 30

Leu Ala Ala Pro Ala Leu Ser Leu Gly His Ala Val Gly Pro Ala Leu

35 40 45

Ser Leu Ser His Thr Ala Leu Ala Ala Pro Ala Ile Ser Leu Gly His

50 55 60

Ala Val Ala Ala Pro Ala Leu Ser Leu Gly His Ala Ala Val Ala Ala

65 70 75 80

Pro Ala Tyr Gly Ile Gly His Gly Leu Gly Leu Gly Tyr Gly Leu Gly

85 90 95

His Gly Ala Ile Ala Ala Pro Ala Leu Val Lys Ala Ala Pro Ala Ile

100 105 110

Val Lys Ala Ala Pro Ala Val Asp Tyr Val Ala Tyr Pro Lys Tyr Glu

115 120 125

Phe Asn Tyr Gly Val Ser Asp Ala His Thr Gly Asp Gln Lys Thr Gln

130 135 140

His Glu Ile Arg Asp Gly Asp Val Val Lys Gly Ser Tyr Ser Leu His

145 150 155 160

Glu Ala Asp Gly Thr Val Arg Thr Val His Tyr Glu Ala Asp Asp His

165 170 175

Asn Gly Phe Asn Ala Val Val Thr Arg Ser Gly His Ala Ala His Pro

180 185 190

Ala Thr Pro Ile Ala Val Ala Ala Pro Ala Lys Thr Ile Ile Ala Ala

195 200 205

Pro Ala Ile Ala His Ala Ala Pro Val Phe Ala His Ala Gly Pro Ala

210 215 220

Leu Ala Tyr Gly Gly Leu Tyr Gly Tyr Lys Gly

225 230 235

<210> 3

<211> 657

<212> DNA

<213> Unknown

<400> 3

ggcctaatac cagctgcacc agctctttcc cttggacatg ccgccctagc agctccagca 60

ctatcgcttg gtcatgctgt tggaccggct ctttcgctta gccatacagc gttagccgcc 120

ccagctatct ctctaggtca tgcagttgct gccccagctc tttctcttgg tcacgccgct 180

gtcgctgctc cagcttacgg aataggtcat ggattgggat tggggtatgg acttggacac 240

ggagccatcg ccgcaccagc tcttgttaaa gccgcacctg ctatcgtaaa ggcagctcca 300

gctgttgatt atgtggcata tccgaaatac gaattcaact acggagtctc cgatgcccac 360

accggcgatc aaaaaaccca acatgaaatc cgcgatggtg acgtagtaaa aggctcatac 420

tccctccacg aagccgatgg caccgtccgt accgtccact acgaagccga tgatcataac 480

ggcttcaacg cagttgtaac cagatcagga cacgctgcgc atcctgctac accaattgcc 540

gtcgcggctc ccgccaaaac catcattgca gctccagcta tagcgcacgc agccccagtc 600

ttcgcgcacg ctggtccagc gttggcgtac ggaggattgt acggttacaa gggttag 657

<210> 4

<211> 708

<212> DNA

<213> Unknown

<400> 4

atgttcgcta aggttttcgc aatcgctaca tttgtagcca ccgcacaagc tggcctaata 60

ccagctgcac cagctctttc ccttggacat gccgccctag cagctccagc actatcgctt 120

ggtcatgctg ttggaccggc tctttcgctt agccatacag cgttagccgc cccagctatc 180

tctctaggtc atgcagttgc tgccccagct ctttctcttg gtcacgccgc tgtcgctgct 240

ccagcttacg gaataggtca tggattggga ttggggtatg gacttggaca cggagccatc 300

gccgcaccag ctcttgttaa agccgcacct gctatcgtaa aggcagctcc agctgttgat 360

tatgtggcat atccgaaata cgaattcaac tacggagtct ccgatgccca caccggcgat 420

caaaaaaccc aacatgaaat ccgcgatggt gacgtagtaa aaggctcata ctccctccac 480

gaagccgatg gcaccgtccg taccgtccac tacgaagccg atgatcataa cggcttcaac 540

gcagttgtaa ccagatcagg acacgctgcg catcctgcta caccaattgc cgtcgcggct 600

cccgccaaaa ccatcattgc agctccagct atagcgcacg cagccccagt cttcgcgcac 660

gctggtccag cgttggcgta cggaggattg tacggttaca agggttag 708

<210> 5

<211> 919

<212> DNA

<213> Unknown

<400> 5

taatacgact cactataggg gaattgtgag cggataacaa ttcccctcta gaaataattt 60

tgtttaactt taagaaggag atataccatg ggcttaatac cagctgcacc agctctttcc 120

cttggacacg ccgccctagc agctccagca ctatcgcttg ggcatgctgt tggaccggct 180

ctttcgctta gccatacagc gttagccgcc ccagctatct ctctaggtca tgcagttgct 240

gctccagctc tttctcttgg tcacgccgct gtcgctgctc cagcttacgg aataggtcat 300

ggattgggat tgggttatgg acttggacac ggagccatcg ccgcaccagc tcttgttaaa 360

gccgcacctg ctatcgtaaa ggcagctcca gctgttgatt atgtggcata tccgaaatac 420

gaattcaact acggagtctc cgatgcccac accggcgatc aaaaaaccca acatgaaatc 480

cgcgatggtg acgtagtaaa aggctcatac tccctccacg aagctgatgg caccgtccgt 540

accgtccact acgaagccga tgatcataac ggcttcaacg cagttgtaac cagatcagga 600

cacgctgcgc atcctgctac accaattgcc gtcgcggctc ccgccaaaac catcattgca 660

gctccagcta tagcgcacgc agccccagtc ttcgcgcacg ctggtccagc gttggcgtac 720

ggaggattgt acggttacaa gggttaggaa ttcgagctcc gtcgacaagc ttgcggccgc 780

actcgagcac caccaccacc accactgaga tccggctgct aacaaagccc gaaaggaagc 840

tgagttggct gctgccaccg ctgagcaata actagcataa ccccttgggg cctctaaacg 900

ggtcttgagg ggttttttg 919

<210> 6

<211> 25

<212> DNA

<213> Artificial Sequence

<400> 6

atgttcgcta aggttttcgc aatcg 25

<210> 7

<211> 28

<212> DNA

<213> Artificial Sequence

<400> 7

ctaacccttg taaccgtaca atcctccg 28

<210> 8

<211> 37

<212> DNA

<213> Artificial Sequence

<400> 8

aggagatata ccatgggctt aataccagct gcaccag 37

<210> 9

<211> 43

<212> DNA

<213> Artificial Sequence

<400> 9

gacggagctc gaattcctaa cccttgtaac cgtacaatcc tcc 43