title: Microbial production of amino acid-modified spider dragline silk protein with intensively improved mechanical properties.
abstract: Spider dragline silk is a remarkably strong fiber with impressive mechanical properties, which were thought to result from the specific structures of the underlying proteins and their molecular size. In this study, silk protein 11R26 from the dragline silk protein of Nephila clavipes was used to analyze the potential effects of the special amino acids on the function of 11R26. Three protein derivatives, ZF4, ZF5, and ZF6, were obtained by site-directed mutagenesis, based on the sequence of 11R26, and among these derivatives, serine was replaced with cysteine, isoleucine, and arginine, respectively. After these were expressed and purified, the mechanical performance of the fibers derived from the four proteins was tested. Both hardness and average elastic modulus of ZF4 fiber increased 2.2 times compared with those of 11R26. The number of disulfide bonds in ZF4 protein was 4.67 times that of 11R26, which implied that disulfide bonds outside the poly-Ala region affect the mechanical properties of spider silk more efficiently. The results indicated that the mechanical performances of spider silk proteins with small molecular size can be enhanced by modification of the amino acids residues. Our research not only has shown the feasibility of large-scale production of spider silk proteins but also provides valuable information for protein rational design.
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhang
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Fengli
authors.initials: F
authors.lastname: Zhou
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Xinglin
authors.initials: X
authors.lastname: Jiang
authors.affiliation: b Department of Chemistry & Chemical Biology , University of Marburg , Marburg , Germany.
authors.forename: Mingle
authors.initials: M
authors.lastname: Cao
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Shilu
authors.initials: S
authors.lastname: Wang
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Huibin
authors.initials: H
authors.lastname: Zou
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Yujin
authors.initials: Y
authors.lastname: Cao
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Mo
authors.initials: M
authors.lastname: Xian
authors.affiliation: a CAS Key Laboratory of Biobased Materials , Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China.
authors.forename: Huizhou
authors.initials: H
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D004220:Disulfides / Q000737:chemistry; D004548:Elasticity; D005285:Fermentation; D019476:Insect Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D008422:Materials Testing; D008854:Microscopy, Electron; D047011:Silk / Q000378:metabolism*; D013112:Spiders
chemical_list: D000596:Amino Acids; D004220:Disulfides; D019476:Insect Proteins; D047011:Silk
keywords: Escherichia coli; Nephila clavipes; heterogeneous expression; rational design; spider silk protein