Biochemical and Domain Analyses of FSUAxe6B, a Modular Acetyl Xylan Esterase, Identify a Unique Carbohydrate Binding Module in Fibrobacter succinogenes S85

Abstract

Acetyl xylan esterase (EC 3.1.1.72) is a member of a set of enzymes required to depolymerize hemicellulose, especially xylan that is composed of a main chain of ␤-1,4-linked xylopyranoside residues decorated with acetyl side groups.

Domain Analysis of a Modular α- l -Arabinofuranosidase with a Unique Carbohydrate Binding Strategy from the Fiber-Degrading Bacterium Fibrobacter succinogenes S85

“…The primers used for cloning the FPm-1 modules appended to FSUAXH1, FSU2263, FSU2265, and FSU2272 are shown in Table S1 of the supplemental material. The cloning, expression, purification of the recombinant proteins and the binding activities were the same as described earlier for FSUAxe6B (74).…”

“…All genes encoding derivatives of FSUAXH1 were sequenced to confirm the integrity of the coding sequence after cloning into the expression vector. The gene expression vectors for FSUAXH1 or its truncated derivatives were introduced individually into E. coli BL21(DE3) CodonPlus RIPL competent cells, and the proteins were expressed as described in our previous study (74). All proteins were purified through the HisTrap FF column (GE Healthcare, Piscataway, NJ).…”

“…2A), composed of a signal peptide, a GH43 catalytic module, a ␤-sandwich-shaped unassigned domain (XX domain), a CBM6, and FPm-1. A member of FPm-1 was recently assigned a function as a carbohydrate-binding module (74). Since arabinoxylan serves as a good substrate for catalysis by FSUAXH1, it was investigated as a substrate for carbohydrate binding by its CBM6.…”

“…Interestingly, the genome of this bacterium also codes for many hemicellulolytic enzymes, despite its limited utilization of hemicellulose (41). To gain insight into this unusual metabolism, we have been studying a hemicellulolytic gene cluster that encodes more than 10 hemicellulosetargeting enzymes in the genome of F. succinogenes S85 (74). In this study, it is demonstrated that a GH43 modular protein (FSU2269) in the cluster (see Fig.…”

Effects of aromatic amino acids, phenylacetate and phenylpropionate on fermentation of xylan by species of rumen anaerobic bacteria

“…They also noted that although R. albus 7, R. flavefaciens (C94 and FD1) and F. succinogenes S85 appeared to ferment xylan to some extent, only small amounts were utilized, and therefore little or no growth occurred. Studies by Jun et al (2003) and Yoshida et al (2010) clearly indicate that F. succinogenes S85 has xylanase genes that enable production of enzymes that can degrade xylan.…”