Xyn11A, a multidomain multicatalytic enzyme fromPseudobutyrivibrio xylanivorans Mz5T

Abstract

The rumen bacterium Pseudobutyrivibrio xylanivorans Mz5T has a potent xylanolytic enzyme system. A small native peptide (approximately 30-kDa, designated Xyn11A) from the bacterium was first isolated and characterized by Edman degradation. The gene coding for Xyn11A was identified using PCR amplification with consensus primers. It was then fully sequenced to reveal an open reading frame of 1809 bp. The predicted N-terminal domain exhibited xylanolytic activity and was classed to the family 11 of glycosyl hydrolases; it is followed by a region with homology to a family 6 cellulose binding module. The C-terminal domain codes for a putative NodB-like polysaccharide deacetylase which is predicted to be an acetyl esterase implicated in debranching activity in the xylan backbone. As similar domain organization was also found in several other xylanases from a diverse range of bacteria, a common ancestor of such a xylanase is considered to be present and spread, possibly by horizontal gene transfer, to other microorganisms from different ecological niches.

Structural Insights into the Dual-Substrate Recognition and Catalytic Mechanisms of a Bifunctional Acetyl Ester–Xyloside Hydrolase from Caldicellulosiruptor lactoaceticus

“…Although the cleaving efficiency ( k cat / K m ) of CLH10 toward the β-1,4-xylosidic bond was not sufficient for the enzymatic degradation of xylan on an industrial scale, the substitution of Asp135 by Ala with improved activity exhibited potential for protein engineering to improve the β-1,4-xylanase activity of CLH10. Additionally, compared to previously reported AEXH, such as Xyn11A and rPcAxe2, CLH10 has a lower molecular weight, which could decrease its cost in biotechnology applications.…”

“…For example, the sequence of AEXH from Neocallimastix patriciarum (XynS20E) includes the conserved domain of family 1 carbohydrate esterase at the N-terminus and the conserved domain of family 11 glycosyl hydrolase at the C-terminus . The sequence of AEXH from Pseudobutyrivibrio xylanivorans Mz5 T (Xyn11A) encodes the acetyl xylan esterase domain NodB and the conserved domain of family 11 glycosyl hydrolases, and the domains are linked by the saccharide-binding module from family 6 (CBM6) . However, CLH10 is a rare single-SR bifunctional enzyme with CSG and CSE fragments distributing in a mixed type (Figure B).…”

Bifunctional xylanases and their potential use in biotechnology

“…Xyl 11A isolated from this bacterium belongs to the glycosyl hydrolase 11 (cellulase G) family. The gene encoding for Xyl 11A contains N-terminal CBM6 (cabohydrate binding type-6) domain, which exibit xylanolytic activity, and C-terminal domain coding for putative polysaccharide deacylase implicated in removing acetyl groups from acetylated xylan, and thus it is probably capable of hydrolyzing acetylated xylan debranching in the xylan backbone [14]. Cytophaga hutchinsonii is reported to produce bifunctional xylanase/esterase enzyme coded by CHU-1239 gene CHU-1240, where xylanase belongs to glycoside hydrolase family 8 proteins and esterase belong to carbohydrate esterase family 4 proteins.…”

Prediction of optimum reaction conditions for the thermo‐tolerant acetylxylan esterase from Neocallimastix patriciarum using the response surface methodology

“…Several genes encoding for acetylxylan esterases have been isolated from bacteria, such as Clostridium cellulovorans ,10 Fibrobacter succinogenes ,11 Pseudobutyrivibrio xylanivorans ,12 Ruminococcus flavefaciens ,13 and Streptomyces lividans ,6 as well as fungi, such as Aspergillus niger ,14 Penicillium purpurogenum ,15 Schizophyllum commune ,16 and Trichoderma reesei 17. According to the CAZy database (http://www.cazy.org/), carbohydrate esterases are classified into 16 families based on their sequence similarities; acetylxylan esterases are found in families 1–7, and 12.…”