The modular arabinanolytic enzyme Abf43A-Abf43B-Abf43C from Ruminiclostridium josui consists of three GH43 modules classified in different subfamilies

Publication date: Available online 30 January 2019Source: Enzyme and Microbial TechnologyAuthor(s): Makiko Sakka, Kazunobu Yamada, Taichi Kitamura, Emi Kunitake, Tetsuya Kimura, Kazuo SakkaABSTRACTThe abnA gene from Ruminiclostridium josui encodes the large modular arabinanolytic enzyme, Abf43 A-Abf43B-Abf43C, consisting of an N-terminal signal peptide, a Laminin_G_3 module, a GH43_22 module, a Laminin_G_3 module, a Big_4 module, a GH43_26 module, a GH43_34 module and a dockerin module in order with a calculated molecular weight of 204,108. Three truncated enzymes were recombinantly produced in Escherichia coli and biochemically characterized, RjAbf43 A consisting of the first Laminin_G_3 module and GH43_22 module, RjAbf43B consisting of the second Laminin_G_3 module, Big_4 module and GH43_26 module, and RjAbf43C consisting of the GH43_34 module. RjAbf43 A showed a strong α-l-arabinofuranosidase activity toward sugar beet arabinan, highly branched arabinan but not linear arabinan, thus it acted in the removal of arabinose side chains from sugar beet arabinan. By contrast, RjAbf43B showed a strong exo-α-1,5-l-arabinofuranosidase activity toward linear arabinan and arabinooligosaccharides whereas RjAbf43C showed low activity toward these substrates. Although RjAbf43B was activated by the presence of some metal ions such as Zn2+, Mg2+ and Ni2+, RjAbf43 A was inhibited by these ions. RjAbf43 A and RjAbf43B attacked sugar beet arabinan in a synergistic manner. By compa...
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research