The role of local residue environmental changes in thermostable mutants of the GH11 xylanase from Bacillus subtilis

Author(s)

Silva, Sergio Bergamachi ; Pinheiro, Matheus Pinto ; Fuzo, Carlos Alessandro ; Silva, Samuel Reghim ; Ferreira, Tatiane Lopes ; Lourenzoni, Marcos Roberto ; Nonato, M. Cristina ; Vieira, Davi Serradella ; Ward, Richard John

• Document type: Journal article
• Source: International Journal of Biological Macromolecules; v. 97, p. 574-584, APR 2017.
• Web of Science Citations: 2

Abstract

A thermostable variant of the mesophilic xylanase A from Bacillus subtilis (BsXynA-G3\_4x) contains the four mutations Gln7His, Gly13Arg, Ser22Pro, and Ser179Cys. The crystal structure of the BsXynA-G3\_4x has been solved, and the local environments around each of these positions investigated by molecular dynamics (MD) simulations at 328 K and 348 K. The structural and MD simulation results were correlated with thermodynamic data of the wild-type enzyme, the 4 single mutants and the BsXynA-G3\_4x. This analysis suggests that the overall stabilizing effect is entropic, and is consistent with solvation of charged residues and reduction of main-chain flexibility. Furthermore, increased protein-protein hydrogen bonding and hydrophobic interactions also contribute to stabilize the BsXynA-G3\_4x. The study revealed that a combination of several factors is responsible for increased thermostability of the BsXynA-G3\_4x; (i) introduction of backbone rigidity in regions of high flexibility, (ii) solvation effects and (iii) hydrophobic contacts. (C) 2017 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 10/18850-2 - Identification, characterization and engineering of plant cell wall degrading enzymes
• Grantee: Richard John Ward
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 12/01066-2 - Design of multifunctional enzymes that combine the hydrolysis of B-glucans and Xylans to evaluate the conformation of these polysaccharides in plant cell walls
• Grantee: Matheus Pinto Pinheiro
• Support Opportunities: Scholarships in Brazil - Post-Doctoral