title: Improving Trichoderma reesei Cel7B thermostability by targeting the weak spots.
abstract: For proteins that denature irreversibly, the denaturation is typically triggered by a partial unfolding, followed by a permanent change (e.g., aggregation). The regions that initiate the partial unfolding are named "weak spots". In this work, a molecular dynamics (MD) simulation and data analysis protocol is developed to identify the weak spots of Trichoderma reesei Cel7B, an important endoglucanase in cellulose hydrolysis, through assigning the local melting temperature (Tmp) to individual residue pairs. To test the predicted weak spots, a total of eight disulfide bonds were designed in these regions and all enhanced the enzyme thermostability. The increased stability, quantified by ΔT50 (which is the T50 difference between the mutant and the wild type enzyme), is negatively correlated with the MD-predicted Tmp, demonstrating the effectiveness of the protocol and highlighting the importance of the weak spots. Strengthening interactions in these regions proves to be a useful strategy in improving the thermostability of Tr. Cel7B.
authors.affiliation: Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences , Qingdao, 266061, China.
authors.forename: Shujun
authors.initials: S
authors.lastname: Zhang
authors.forename: Yefei
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiangfei
authors.initials: X
authors.lastname: Song
authors.forename: Jingbo
authors.initials: J
authors.lastname: Hong
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lishan
authors.initials: L
authors.lastname: Yao
mesh_terms: D002480:Cellulase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry* / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006868:Hydrolysis; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D009154:Mutation; D044367:Phase Transition; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D013816:Thermodynamics; D014242:Trichoderma / Q000737:chemistry* / Q000201:enzymology
chemical_list: D004220:Disulfides; D005656:Fungal Proteins; D011994:Recombinant Proteins; D002482:Cellulose; D002480:Cellulase