Heterologous expression in Pichia pastoris and characterization of a β-glucosidase from the xylophagous cockroach Panesthia angustipennis spadica displaying high specific activity for cellobiose

Publication date: Available online 15 November 2016 Source:Enzyme and Microbial Technology Author(s): Yihai Li, Gaku Arakawa, Gaku Tokuda, Hirofumi Watanabe, Manabu Arioka A β-glucosidase (BG), PaBG1b, from the xylophagous cockroach Panesthia angustipennis spadica was heterologously expressed in the methylotrophic yeast Pichia pastoris, purified, and biochemically characterized. Post-translational modification and N-terminal sequencing analysis demonstrated that the expression product was comprised of two polypeptides with different N-terminal sequences, presumably due to the presence of lysine-arginine (KR) sequence in the putative mature region. Substrate specificity analysis showed that PaBG1b hydrolyzed a broad range of substrates including cellohexaose, with the preference for aryl β-D-fucosyl linkage and laminaribiose. Although the glucose tolerance of PaBG1b was moderate (K i =200.3±1.1mM), PaBG1b demonstrated high specific activity and catalytic efficiency towards cellobiose with V max and k cat /K m values of 436.7±6.3U/mg and 109.8mM−1·s−1, respectively. In addition, PaBG1b was not inhibited by cellobiose up to the highest concentration tested (100mM). Collectively, our work demonstrates that PaBG1b is a potentially valuable BG for commercial bioethanol production from cellulose.
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research
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