title: Enhanced thermostability of keratinase by computational design and empirical mutation.
abstract: Keratinases are proteolytic enzymes capable of degrading insoluble keratins. The importance of these enzymes is being increasingly recognized in fields as diverse as animal feed production, textile processing, detergent formulation, leather manufacture, and medicine. To enhance the thermostability of Bacillus licheniformis BBE11-1 keratinase, the PoPMuSiC algorithm was applied to predict the folding free energy change (ΔΔG) of amino acid substitutions. Use of the algorithm in combination with molecular modification of homologous subtilisin allowed the introduction of four amino acid substitutions (N122Y, N217S, A193P, N160C) into the enzyme by site-directed mutagenesis, and the mutant genes were expressed in Bacillus subtilis WB600. The quadruple mutant displayed synergistic or additive effects with an 8.6-fold increase in the t 1/2 value at 60 °C. The N122Y substitution also led to an approximately 5.6-fold increase in catalytic efficiency compared to that of the wild-type keratinase. These results provide further insight into the thermostability of keratinase and suggest further potential industrial applications.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China.
authors.forename: Baihong
authors.initials: B
authors.lastname: Liu
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Fang
authors.forename: Lei
authors.initials: L
authors.lastname: Gu
authors.forename: Xiangru
authors.initials: X
authors.lastname: Liao
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism; D019295:Computational Biology; D003198:Computer Simulation; D019020:Directed Molecular Evolution; D004795:Enzyme Stability / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013381:Subtilisins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D050505:Mutant Proteins; D010447:Peptide Hydrolases; C035855:keratinase; D013381:Subtilisins