5t4c
Crystal structure of BhGH81 mutant in complex with laminaro-hexaose
Structural highlights
FunctionENG1_HALH5 Cleaves internal linkages in 1,3-beta-glucan (PubMed:15501830, PubMed:28827308, PubMed:28781080). May contribute to plant biomass degradation (By similarity).[UniProtKB:Q47N06][1] [2] [3] Publication Abstract from PubMedFamily 81 glycoside hydrolases (GHs), which are known to cleave beta-1,3-glucans, are found in archaea, bacteria, eukaryotes, and viruses. Here we examine the structural and functional features of the GH81 catalytic module, BhGH81, from the Bacillus halodurans protein BH0236 to probe the molecular basis of beta-1,3-glucan recognition and cleavage. BhGH81 displayed activity on laminarin, curdlan, and pachyman, but not scleroglucan; the enzyme also cleaved beta-1,3-glucooligosaccharides as small as beta-1,3-glucotriose. The crystal structures of BhGH81 in complex with various beta-1,3-glucooligosaccharides revealed distorted sugars in the -1 catalytic subsite and an arrangement consistent with an inverting catalytic mechanism having a proposed conformational itinerary of (2)S0 --> (2,5)B(double dagger) --> (5)S1. Notably, the architecture of the catalytic site, location of an adjacent ancillary beta-1,3-glucan binding site, and the surface properties of the enzyme indicate the likely ability to recognize the double and/or triple-helical quaternary structures adopted by beta-1,3-glucans. Structural Analysis of a Family 81 Glycoside Hydrolase Implicates Its Recognition of beta-1,3-Glucan Quaternary Structure.,Pluvinage B, Fillo A, Massel P, Boraston AB Structure. 2017 Sep 5;25(9):1348-1359.e3. doi: 10.1016/j.str.2017.06.019. Epub, 2017 Aug 3. PMID:28781080[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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