title: Native-sized recombinant spider silk protein produced in metabolically engineered Escherichia coli results in a strong fiber.
abstract: Spider dragline silk is a remarkably strong fiber that makes it attractive for numerous applications. Much has thus been done to make similar fibers by biomimic spinning of recombinant dragline silk proteins. However, success is limited in part due to the inability to successfully express native-sized recombinant silk proteins (250-320 kDa). Here we show that a 284.9 kDa recombinant protein of the spider Nephila clavipes is produced and spun into a fiber displaying mechanical properties comparable to those of the native silk. The native-sized protein, predominantly rich in glycine (44.9%), was favorably expressed in metabolically engineered Escherichia coli within which the glycyl-tRNA pool was elevated. We also found that the recombinant proteins of lower molecular weight versions yielded inferior fiber properties. The results provide insight into evolution of silk protein size related to mechanical performance, and also clarify why spinning lower molecular weight proteins does not recapitulate the properties of native fibers. Furthermore, the silk expression, purification, and spinning platform established here should be useful for sustainable production of natural quality dragline silk, potentially enabling broader applications.
authors.affiliation: Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Program), BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Korea.
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Xia
authors.forename: Zhi-Gang
authors.initials: ZG
authors.lastname: Qian
authors.forename: Chang Seok
authors.initials: CS
authors.lastname: Ki
authors.forename: Young Hwan
authors.initials: YH
authors.lastname: Park
authors.forename: David L
authors.initials: DL
authors.lastname: Kaplan
authors.forename: Sang Yup
authors.initials: SY
authors.lastname: Lee
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics*; D055595:Mechanical Phenomena; D008970:Molecular Weight; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D047011:Silk / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D013112:Spiders
chemical_list: D012346:RNA, Transfer, Amino Acyl; D011994:Recombinant Proteins; D047011:Silk