Multifunctional Properties of Glycoside Hydrolase Family 43 from Paenibacillus curdlanolyticus Strain B-6 Including Exo-β-xylosidase, Endo-xylanase, and α-L-Arabinofuranosidase Activities

Novel Trifunctional Xylanolytic Enzyme Axy43A from Paenibacillus curdlanolyticus Strain B-6 Exhibiting Endo-Xylanase, β- d -Xylosidase, and Arabinoxylan Arabinofuranohydrolase Activities

“…Moreover, the k cat /K m values toward X2 and X6 were 166 and 203 mM Ϫ1 · s Ϫ1 , respectively, indicating that PcAxy43A prefers longchain XOS to short-chain XOS. These properties are similar to those of GH43B6 in XOS (X2 and X6) hydrolysis (19) and contrast with those of true ␤-xylosidases that are capable of efficiently and exactly degrading X2 (9) and often demonstrate higher activity on X2 than on longer XOSs (39).…”

“…The GH43 enzyme of uncultured bacterium r_09 has a 30-amino-acid stretch (amino acids 172 to 181) that was not found in the other enzymes. On the other hand, based on the pairwise alignment, the amino acid sequence of PcAxy43A was 27% identical to the extracellular multifunctional GH43B6, exo-␤-xylosidase/endo-xylanase/␣-L-arabinofuranosidase, from the same microbial source (19). The CBM6 domain of PcAxy43A showed 62%, 60%, and 31% sequence identities against those of P. woosongensis XylC, C. stercorarium XylA, and the uncultured bacterium r_09 GH43 enzyme.…”

“…CBM6s have been reported to interact with different substrates, such as xylan, XOS, cellulose, cellooligosaccharide, laminarin, and glucan (3). CBMs assist hydrolysis of insoluble substances by bringing the catalytic domain in close proximity to its substrate (19). Although GH43 members have different activities and substrate preferences, three essential residues (3) are conserved as Asp18, Asp144, and Glu209 in PcAxy43A and other enzymes (Fig.…”

“…The reaction was stopped by the addition of 1 ml of 1 M sodium carbonate. The absorbance at 410 nm was measured (19). One unit of enzymatic activity was defined as the amount of enzyme that released 1 mol pNP per min.…”

“…curdlanolyticus B-6, a facultatively anaerobic bacterium, has great potential in plant biomass degradation (21). Most of the enzymes characterized from the B-6 strain are endo-xylanases belonging to GH10 and GH11 (22), and a few other xylanolytic enzymes, such as a multifunctional GH43B6 exo-␤-xylosidase/ endo-xylanase/␣-L-arabinofuranosidase (19) and a GH67 ␣-glucuronidase (23), have been studied. In this work, we found a new gene, axy43A, from strain B-6, encoding an intracellular GH43 enzyme (PcAxy43A) with a high sequence similarity with enzymes of GH43 subfamily 35, including C. stercorarium XylA (13) and P. woosongensis XylC (14), which were reported to be bifunctional ␤-xylosidase/␣-L-arabinofuranosidases.…”