Method and Compositions for Synthesizing Improved Silk Fibers

Patent metadata

Field	Value
Publication number	US-2016222174-A1
Application number	US-201615073514-A
Country	US
Kind code	A1
Filing date	Mar 17, 2016
Priority date	Sep 17, 2013
Publication date	Aug 4, 2016
Grant date	—

Abstract

The present disclosure provides methods and compositions for directed to synthetic block copolymer proteins, expression constructs for their secretion, recombinant microorganisms for their production, and synthetic fibers (including advantageously, microfibers) comprising these proteins that recapitulate many properties of natural silk. The recombinant microorganisms can be used for the commercial production of silk-like fibers.

First claim

What is claimed is:

1 . A proteinaceous block co-polymer, comprising:
a polypeptide, the polypeptide comprising from 2 to 8 concatenated repeats of SEQ ID NO: 1396 or circularly permuted variants thereof.

2 . The proteinaceous block co-polymer of claim 1 , wherein the polypeptide comprises a property selected from the group consisting of an alanine composition from 12 to 40%, a glycine composition from 25 to 50%, a proline composition from 9 to 20%, a β-turn composition from 15 to 37%, a GPG amino acid motif content from 18 to 55%, and a poly-alanine amino acid motif content from 9 to 35%.

3 . The proteinaceous block co-polymer of claim 1 , consisting of: 3 concatenated repeats of SEQ ID NO: 1396.

4 . A fiber comprising the block co-polymer of claim 1 .

5 . The fiber of claim 4 , comprising a circular cross-section and a diameter from 4.48 to 12.7 μm.

6 . The fiber of claim 4 , wherein the fiber has a yield stress from 24 to 172 MPa.

7 . The fiber of claim 4 , wherein the fiber has a maximum stress from 54 to 310 MPa.

8 . The fiber of claim 4 , wherein the fiber has a breaking strain from 2 to 200%.

9 . The fiber of claim 4 , wherein the fiber has an initial modulus from 1617 to 5820 MPa.

10 . The fiber of claim 4 , wherein the fiber has a toughness value from 0.5 MJ/m 3 to 59.2 MJ/m 3 .

11 . An expression construct encoding the proteinaceous block co-polymer of claim 1 .

12 . The expression construct of claim 11 , further comprising a secretion signal operatively linked to the coding sequence for the block copolymer polypeptide.

13 . The expression construct of claim 12 , wherein the secretion signal comprises an alpha mating factor leader and pro sequence.

14 . A host cell, comprising: the expression construct of claim 11 .

15 . A host cell, comprising: the expression construct of claim 12 .

16 . A host cell, comprising: the expression construct of claim 13 .

17 . A method of producing the proteinaceous block copolymer of claim 1 , comprising:
culturing the host cell of claim 14 under conditions that promote expression of the block copolymer polypeptide from the expression construct; and recovering the expressed block copolymer.

18 . A method of producing the proteinaceous block copolymer of claim 1 , comprising:
culturing the host cell of claim 15 under conditions that promote expression of the block copolymer polypeptide from the expression construct; and recovering the secreted block copolymer.

19 . A culture medium comprising a secreted block copolymer of claim 1 .

20 . A method for producing a fiber, comprising:
obtaining the cell culture medium of claim 19 ; isolating the secreted protein; processing the protein into a spinnable solution; and producing a fiber from the spinnable solution.

Assignees

• Bolt Threads Inc

Inventors

• Widmaier Daniel M
• Breslauer David N
• Kittleson Joshua
• Turner Brendan
• Wray Lindsay

Classifications

• C07K14/43586

  from silkworms · CPC title

• B29K2995/0077

  Yield strength; Tensile strength · CPC title

• D01F4/02

  from fibroin · CPC title

• B29L2031/731

  Filamentary material, i.e. comprised of a single element, e.g. filaments, strands, threads, fibres (cables B29L2031/707) · CPC title

• B29K2089/00

  Use of proteins, e.g. casein, gelatine or derivatives thereof, as moulding material · CPC title