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Publication Abstract from PubMed

GH11 xylanase XynJ from Bacillus sp. strain 41M-1 has a beta-jellyroll fold composed of eight beta strands with a deep active-site cleft. We hypothesized that the thermostability of XynJ will increase if the flexibility of the beta strands in the jellyroll structure is decreased without impairing activity. To verify this hypothesis, we introduced random mutations into Tyr13-Arg104 and Gly169-Tyr194, both of which are located in the beta-jellyroll fold of XynJ, to construct a site saturation mutagenesis library. By screening 576 clones followed by site saturation mutation analysis of Thr82, T82A was selected as the most thermostable variant. In the hydrolysis of beechwood xylan at pH 7.8, the temperatures required to reduce initial activity by 50% in 15 min were 61  degrees C for the wild-type XynJ (WT) and 65  degrees C for T82A. The optimum hydrolysis temperatures were 60  degrees C for WT and 65  degrees C for T82A. There was little difference in the k(cat) and K(m) values and the pH dependence of activity between WT and T82A. Crystallographic analysis of WT and T82A revealed that thermostabilization by the T82A mutation might result from the removal of unfavorable van der Waals interactions. Thus, a highly thermostable XynJ variant was generated without impairing activity using this mutation strategy.

Increase in the thermostability of GH11 xylanase XynJ from Bacillus sp. strain 41M-1 using site saturation mutagenesis.,Takita T, Nakatani K, Katano Y, Suzuki M, Kojima K, Saka N, Mikami B, Yatsunami R, Nakamura S, Yasukawa K Enzyme Microb Technol. 2019 Nov;130:109363. doi: 10.1016/j.enzmictec.2019.109363. , Epub 2019 Jun 18. PMID:31421720^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.