In:
Acta Crystallographica Section F Structural Biology Communications, International Union of Crystallography (IUCr), Vol. 76, No. 8 ( 2020-08-01), p. 341-349
Abstract:
GH30-7 endoxylanase C from the cellulolytic fungus Talaromyces cellulolyticus ( Tc Xyn30C) belongs to glycoside hydrolase family 30 subfamily 7, and specifically releases 2 2 -(4- O -methyl-α-D-glucuronosyl)-xylobiose from glucuronoxylan, as well as various arabino-xylooligosaccharides from arabinoxylan. Tc Xyn30C has a modular structure consisting of a catalytic domain and a C-terminal cellulose-binding module 1 (CBM1). In this study, the crystal structure of a Tc Xyn30C mutant which lacks the CBM1 domain was determined at 1.65 Å resolution. The structure of the active site of Tc Xyn30C was compared with that of the bifunctional GH30-7 xylanase B from T. cellulolyticus ( Tc Xyn30B), which exhibits glucuronoxylanase and xylobiohydrolase activities. The results revealed that Tc Xyn30C has a conserved structural feature for recognizing the 4- O -methyl-α-D-glucuronic acid (MeGlcA) substituent in subsite −2b. Additionally, the results demonstrated that Phe47 contributes significantly to catalysis by Tc Xyn30C. Phe47 is located in subsite −2b and also near the C-3 hydroxyl group of a xylose residue in subsite −2a. Substitution of Phe47 with an arginine residue caused a remarkable decrease in the catalytic efficiency towards arabinoxylan, suggesting the importance of Phe47 in arabinoxylan hydrolysis. These findings indicate that subsite −2b of Tc Xyn30C has unique structural features that interact with arabinofuranose and MeGlcA substituents.
Type of Medium:
Online Resource
ISSN:
2053-230X
DOI:
10.1107/S2053230X20009024
Language:
Unknown
Publisher:
International Union of Crystallography (IUCr)
Publication Date:
2020
detail.hit.zdb_id:
2175956-X
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