Probing Substrate Promiscuity of Amylosucrase from Neisseria polysaccharea

The amylosucrase from Neisseria polysaccharea (NpAS) naturally catalyzes the synthesis of a variety of products from sucrose and shows signs of plasticity of its active site. p-nitrophenyl-alpha D-glucopyranoside was used by the wild-type enzyme, and this underlines the high specificity of the -1 subsite of NpAS for glucosyl donor substrates. D- and L-monosaccharides as well as polyols. With the exception of one compound, all were successfully glucosylated, and this showcases the tremendous plasticity of the +1 subsite of NpAS, which is responsible for acceptor recognition. The products obtained from the transglucosylation reactions of three selected acceptors were characterized, and they revealed original structures and enzyme enantiopreference, which were more particularly analyzed by in silico docking analyses.