Biochemical and Biophysical Research Communications, Vol.529, No.4, 876-881, 2020
Structural and biochemical analyses of beta-N-acetylhexosaminidase Am0868 from Akkermansia muciniphila involved in mucin degradation
beta-N-acetylhexosaminidases from the gut microbes are found to be capable of cleaving the specific glycoside linkages in the process of mucin degradation that has relevance for human health. However, features of the enzyme used in regulating the sugar-degrading capacities of Akkermansia muciniphila have not been well defined. Here we reported the crystal structure of a novel beta-N-acetylhexosaminidase from Akkermansia muciniphila (Am0868), which displayed a typical (beta/alpha)(8) barrel fold with a GlcNAc bound to the active center. Crystallographic and subsequent mutagenic analyses confirmed that Asp326 and Glu327 are the key catalytic residues of Am0868. Furthermore, Am0868 exhibited high specificity to beta-GlcNAc supporting the substrate-assisted catalytic mechanism. Am0868 was also active in a broad pH and temperature range but inhibited strongly by metal ions Zn2+ and Cu2+ . Collectively, these results indicate that Am0868 has the potential for mucin hydrolysis under some severe conditions, which highlight the superiority of A. muciniphila surviving in gut. (c) 2020 Elsevier Inc. All rights reserved.