Enhancement in catalytic activity of Aspergillus niger XynB by selective site-directed mutagenesis of active site amino acids

Xiuyun Wu, Zhennan Tian, Xukai Jiang, Qun Zhang, Lushan Wang

Research output: Contribution to journalArticleResearchpeer-review

17 Citations (Scopus)

Abstract

XynB from Aspergillus niger ATCC1015 (AnXynB) is a mesophilic glycoside hydrolase (GH) family 11 xylanase which holds great potentials in a wide variety of industrial applications. In the present study, the catalytic activity and stability of AnXynB were improved by a combination of computational and experimental approaches. Virtual mutation and molecular dynamics simulations indicated that the introduction of Glu and Asn altered the interaction network at the − 3 subsite. Interestingly, the double mutant S41N/T43E displayed 72% increase in catalytic activity when compared to the wild type (WT). In addition, it also showed a better thermostability than the WT enzyme. Kinetic determination of the T43E and S41N/T43E mutants suggested that the higher xylanase activity is probably due to the increasing binding affinity of enzyme and substrate. Consequently, the enzyme activity and thermostability of AnXynB was both increased by selective site-directed mutagenesis at the − 3 subsite of its active site architecture which provides a good example for a successfully engineered enzyme for potential industrial application. Moreover, the molecular evolution approach adopted in this study led to the design of a library of sequences that captures a meaningful functional diversity in a limited number of protein variants.

Original languageEnglish
Pages (from-to)249-260
Number of pages12
JournalApplied Microbiology and Biotechnology
Volume102
Issue number1
DOIs
Publication statusPublished - Jan 2018
Externally publishedYes

Keywords

  • Active site architecture
  • Binding affinity
  • Catalytic activity
  • GH11xylanase
  • Rational design

Cite this