A New Subfamily of Glycoside Hydrolase Family 30 with Strict Xylobiohydrolase Function

• Published in: Frontiers in molecular biosciences Vol. 8; p. 714238
• Main Authors: Crooks, Casey, Bechle, Nathan J., St John, Franz J.
• Format: Journal Article
• Language: English
• Published: United States Frontiers Media S.A 07-09-2021
• Subjects: Acetivibrio clariflavus; AcXbh30A; Biochemistry & Molecular Biology; glycoside hydrolase; glycoside hydrolase family 30; Molecular Biosciences; xylobiohydrolase; xylobiose
• ISSN: 2296-889X; 2296-889X
• DOI: 10.3389/fmolb.2021.714238

The
Acetivibrio
clariflavus
(basonym:
Clostridium clariflavum
) glycoside hydrolase family 30 cellulosomal protein encoded by the Clocl_1795 gene was highly represented during growth on cellulosic substrates. In this report, the recombinantly expressed protein has been characterized and shown to be a non-reducing terminal (NRT)-specific xylobiohydrolase (
Ac
Xbh30A). Biochemical function, optimal biophysical parameters, and phylogeny were investigated. The findings indicate that
Ac
Xbh30A strictly cleaves xylobiose from the NRT up until an α-1,2-linked glucuronic acid (GA)-decorated xylose if the number of xyloses is even or otherwise a single xylose will remain resulting in a penultimate GA-substituted xylose. Unlike recently reported xylobiohydrolases,
Ac
Xbh30A has no other detectable hydrolysis products under our optimized reaction conditions. Sequence analysis indicates that
Ac
Xbh30A represents a new GH30 subfamily. This new xylobiohydrolase may be useful for commercial production of industrial quantities of xylobiose.