Multi-functionality of a tryptophan residue conserved in substrate-binding groove of GH19 chitinases.

ABSTRACT: GH19 and GH22 glycoside hydrolases belonging to the lysozyme superfamily have a related structure/function. A highly conserved tryptophan residue, Trp103, located in the binding groove of a GH19 chitinase from moss Bryum coronatum (BcChi-A) appears to have a function similar to that of well-known Trp62 in GH22 lysozymes. Here, we found that mutation of Trp103 to phenylalanine (W103F) or alanine (W103A) strongly reduced the enzymatic activity of BcChi-A. NMR experiments and the X-ray crystal structure suggested a hydrogen bond between the Trp103 side chain and the -2 sugar. Chitooligosaccharide binding experiments using NMR indicated that the W103F mutation reduced the sugar-binding abilities of nearby amino acid residues (Tyr105/Asn106) in addition to Trp103. This appeared to be derived fr

SUBMITTER: Nagata T 

PROVIDER: S-EPMC7844276 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature