Dragline protein

Abstract

To provide a new natural fiber material with excellent physical properties. Any one of the following nucleic acids (a) to (d): (a) a nucleic acid having a base sequence of SEQ ID NO: 1 or 19; (b) a nucleic acid encoding a protein having an amino acid sequence of SEQ ID NO: 2 or 20; (c) a nucleic acid encoding a dragline protein and having a sequence identity of 90% or more with the nucleic acid (a); (d) a nucleic acid which encodes a dragline protein and hybridizes with a complementary chain of the nucleic acid (a) under stringent conditions.

What is claimed is: 
     
         1 . Any one of the following nucleic acids (a) to (d):
 (a) a nucleic acid having a base sequence of SEQ ID NO: 1 or 19;   (b) a nucleic acid encoding a protein having an amino acid sequence of SEQ ID NO: 2 or 20;   (c) a nucleic acid encoding a dragline protein and having a sequence identity of 90% or more with the nucleic acid (a);   (d) a nucleic acid which encodes a dragline protein and hybridizes with a complementary chain of the nucleic acid (a) under stringent conditions.   
     
     
         2 . A nucleic acid encoding a dragline protein, comprising any one of the following nucleic acids (e) to (h) and having a sequence identity of 70% or more with a nucleic acid having the base sequence of SEQ ID NO: 1:
 (e) a nucleic acid having a base sequence of SEQ ID NO: 3, 5, 7, 9, 11, 13, 15 or 17;   (f) a nucleic acid encoding a protein having an amino acid sequence of SEQ ID NO: 4, 6, 8, 10, 12, 14, 16 or 18;   (g) a nucleic acid having a sequence identity of 90% or more with the nucleic acid (e);   (h) a nucleic acid which hybridizes with a complementary chain of the nucleic acid (e) under stringent conditions.   
     
     
         3 . The nucleic acid according to  claim 2 , having a sequence identity of 80% or more with a nucleic acid having the base sequence of SEQ ID NO: 1. 
     
     
         4 . A nucleic acid encoding a dragline protein, comprising any one of the following nucleic acids (i) to (l) and having a sequence identity of 70% or more with a nucleic acid having the base sequence of SEQ ID NO: 19:
 (i) a nucleic acid having a base sequence of SEQ ID NO: 21, 23, 25, 27, 29, 31, 33 or 35;   (j) a nucleic acid encoding a protein having an amino acid sequence of SEQ ID NO: 22, 24, 26, 28, 30, 32, 34 or 36;   (k) a nucleic acid having a sequence identity of 90% or more with the nucleic acid (i);   (l) a nucleic acid which hybridizes with a complementary chain of the nucleic acid (i) under stringent conditions.   
     
     
         5 . The nucleic acid according to  claim 4 , having a sequence identity of 80% or more with a nucleic acid having a base sequence of SEQ ID NO: 19. 
     
     
         6 . An isolated protein encoded by one of the following nucleic acids (i)-(iv):
 (i) a nucleic acid having the base sequence of SEQ ID NO: 19;   (ii) a nucleic acid encoding a protein having the amino acid sequence of SEQ ID NO: 20;   (iii) a nucleic acid encoding a dragline protein with a base sequence identity of 90% or more to SEQ ID NO: 19; or   (iv) a nucleic acid which encodes a dragline protein and hybridizes with a complementary chain of the nucleic acid of SEQ ID NO: 19 under stringent conditions including hybridization in a buffer solution of 50% formamide, 1M NaCl, 1% SDS at 37° C. and washing with 0.1×SSC at 60° C.   
     
     
         7 . A recombinant organism having the nucleic acid according to  claim 1  introduced therein. 
     
     
         8 . A recombinant silkworm having the nucleic acid according to  claim 1  introduced therein. 
     
     
         9 . A protein according to  claim 6 , which is produced by a recombinant organism. 
     
     
         10 . An isolated silk thread containing the protein according to  claim 6 , produced by a recombinant silkworm. 
     
     
         11 . An isolated dragline protein having an amino acid sequence selected from the group consisting of:
 (i) the amino acid sequence of SEQ ID NO: 20; and   (ii) an amino acid sequence having a sequence identity of 90% or more with SEQ ID NO: 20.   
     
     
         12 . An isolated dragline protein having the following amino acid sequence (i) or (ii) and having a sequence identity of 70% or more with the amino acid sequence of SEQ ID NO: 20,
 (i) an amino acid sequence of SEQ ID NO: 22, 24, 26, 28, 30, 32, 34 or 36;   (ii) an amino acid sequence having a sequence identity of 90% or more with the amino acid sequence (i).   
     
     
         13 . The dragline protein according to  claim 12 , wherein the amino acid sequence has a sequence identity of 80% or more with the amino acid sequence of SEQ ID NO: 20. 
     
     
         14 . A protein having an amino acid sequence represented by the following formula (1) or an amino acid sequence having a sequence identity of 90% or more with the amino acid sequence represented by the formula (1):
   [X1-X2-X3-(X4) m -(X5) m -(X6) m -X7-X8] n   (1)
   
       where each m independently represent an integer of 0 or 1; n represents an integer of 1 to 10; X1 represents any one of amino acid sequences of SEQ ID NO: 37 to 45; X2 represents any one of amino acid sequences of SEQ ID NO: 46 to 52; X3 represents any one of amino acid sequences of SEQ ID NO: 53 to 59; X4 represents an amino acid sequence of SEQ ID NO: 49; X5 represents an amino acid sequence of SEQ ID NO: 60 or 61; X6 represents any one of amino acid sequences of SEQ ID NO: 62 to 64; X7 represents any one of amino acid sequences of SEQ ID NO: 65 to 70; and X8 represents any one of amino acid sequences of SEQ ID NO: 71 to 81.