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Publication Abstract from PubMed

Mannan is an important renewable resource whose backbone can be hydrolyzed by beta-mannanases to generate manno-oligosaccharides of various sizes. Only a few glycoside hydrolase (GH) 113 family beta-mannanases have been functionally and structurally characterize. Here, we report the function and structure of a novel GH113 beta-mannanase from Bacillus sp. N16-5 (BaMan113A). BaMan113A exhibits a substrate preference toward manno-oligosaccharides and releases mannose and mannobiose as main hydrolytic products. The crystal structure of BaMan113A suggest that the enzyme shows a semi-enclosed substrate-binding cleft and the amino acids surrounding the +2 subsite form a steric barrier to terminate the substrate-binding tunnel. Based on these structural features, we conducted mutagenesis to engineer BaMan113A to remove the steric hindrance of the substrate-binding tunnel. We found that F101E and N236Y variants exhibit increased specific activity toward mannans comparing to the wild-type enzyme. Meanwhile, the product profiles of these two variants toward polysaccharides changed from mannose to a series of manno-oligosaccharides. The crystal structure of variant N236Y was also determined to illustrate the molecular basis underlying the mutation. In conclusion, we report the functional and structural features of a novel GH113 beta-mannanase, and successfully improved its endo-acting activity by using structure-based engineering.

Functional and structural investigation of a novel beta-mannanase BaMan113A from Bacillus sp. N16-5.,Liu W, Ma C, Liu W, Zheng Y, Chen CC, Liang A, Luo X, Li Z, Ma W, Song Y, Guo RT, Zhang T Int J Biol Macromol. 2021 Apr 15;182:899-909. doi:, 10.1016/j.ijbiomac.2021.04.075. PMID:33865894^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.