Characterization of Xyn10A, a highly active xylanase from the human gut bacterium Bacteroides xylanisolvens XB1A

Abstract

A xylanase gene xyn10A was isolated from the human gut bacterium Bacteroides xylanisolvens XB1A and the gene product was characterized. Xyn10A is a 40-kDa xylanase composed of a glycoside hydrolase family 10 catalytic domain with a signal peptide. A recombinant His-tagged Xyn10A was produced in Escherichia coli and purified. It was active on oat spelt and birchwood xylans and on wheat arabinoxylans. It cleaved xylotetraose, xylopentaose, and xylohexaose but not xylobiose, clearly indicating that Xyn10A is a xylanase. Surprisingly, it showed a low activity against carboxymethylcellulose but no activity at all against aryl-cellobioside and cellooligosaccharides. The enzyme exhibited K (m) and V (max) of 1.6 mg ml(-1) and 118 micromol min(-1) mg(-1) on oat spelt xylan, and its optimal temperature and pH for activity were 37 degrees C and pH 6.0, respectively. Its catalytic properties (k (cat)/K (m) = 3,300 ml mg(-1) min(-1)) suggested that Xyn10A is one of the most active GH10 xylanase described to date. Phylogenetic analyses showed that Xyn10A was closely related to other GH10 xylanases from human Bacteroides. The xyn10A gene was expressed in B. xylanisolvens XB1A cultured with glucose, xylose or xylans, and the protein was associated with the cells. Xyn10A is the first family 10 xylanase characterized from B. xylanisolvens XB1A.

Arabinoxylans Gels as Lycopene Carriers: in vitro Degradation by Colonic Bacteria

“…These authors reported B. ovatus and B. longum as the strains with major performance on degrading heteroxylans from maize. Similarly, other authors [13,14] have reported these two strains as capable to degrade hemicelluloses. Furthermore, a previous research [15] reported B. longum growing on AX as a sole carbon source and Bacteroides isolates fermenting efficiently xylo-oligasaccharides.…”

“…These results suggest that AX gels degradation could be rather related to the polysaccharide structure and/or cross-linking content and structure. Some authors suggest that the ability of B. longum and B. ovatus to degrade hemicellulose is due to the production of high levels of xylanase [13] and glycosidases [14]. Prebiotic and health related effects of AX, AX-oligosaccharides, and xylooligosaccharides from wheat have been reviewed extensively [15].…”

Molecular Mechanisms Associated with Xylan Degradation by Xanthomonas Plant Pathogens

“…Remarkably, the chimeric XynA showed 20-fold higher catalytic efficiency than the L270R mutant and 15% higher than XynB (Table 3). This catalytic efficiency is at least 7-fold higher than that observed for other mesophilic GH10 xylanases such as CmXyn10B (40), Xyn10A from Bacteroides xylanisolvens (45), and XynA from Glaciecola mesophila (46). Kinetic data revealed a notable improvement of both K m and V max in comparison with the single mutant (Table 3).…”

Newly Cultured Bacteria with Broad Diversity Isolated from Eight-Week Continuous Culture Enrichments of Cow Feces on Complex Polysaccharides

“…Active enzymes targeting plant cell wall carbohydrates have been demonstrated in Bacteroides ovatus, B. thetaiotaomicron, B. xylanisolvens, B. uniformis, and B. fragilis (37)(38)(39). Among the isolates, the majority of the Bacteroidetes were closely related to B. ovatus, B. thetaiotaomicron, and B. xylanisolvens; both B. ovatus and B. thetaiotaomicron have multiple polysaccharide utilization loci that encode a broad range of enzymes targeting various plant cell wall components (39).…”