A C-terminal proline-rich sequence simultaneously broadens the optimal temperature and pH ranges and improves the catalytic efficiency of glycosyl hydrolase family 10 ruminal xylanases.

ABSTRACT: Efficient degradation of plant polysaccharides in rumen requires xylanolytic enzymes with a high catalytic capacity. In this study, a full-length xylanase gene (xynA) was retrieved from the sheep rumen. The deduced XynA sequence contains a putative signal peptide, a catalytic motif of glycoside hydrolase family 10 (GH10), and an extra C-terminal proline-rich sequence without a homolog. To determine its function, both mature XynA and its C terminus-truncated mutant, XynA-Tr, were expressed in Escherichia coli. The C-terminal oligopeptide had significant effects on the function and structure of XynA. Compared with XynA-Tr, XynA exhibited improved specific activity (12-fold) and catalytic efficiency (14-fold), a higher temperature optimum (50°C versus 45°C), and broader ranges of temperature

SUBMITTER: Li Z 

PROVIDER: S-EPMC4018843 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature