Taxonomic group: fungi / Ascomycota
(Phylum: Ascomycota)
The structure was elucidated in this paperNCBI PubMed ID: 25752603Publication DOI: 10.1074/jbc.M114.623579Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: bgfox
biochem.wisc.edu
Institutions: Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, USA, Department of Chemistry, University of Wisconsin-Oshkosh, Oshkosh, USA, Joint Genome Institute, Walnut Creek, USA, Department of Chemistry and Biochemistry, California State University-Fullerton, Fullerton, USA
The Carbohydrate Active Enzyme (CAZy) database indicates that glycoside hydrolase family 55 (GH55) contains both endo- and exo-β-1,3-glucanases. The founding structure in the GH55 is PcLam55A from the white rot fungus Phanerochaete chrysosporium (Ishida, T., Fushinobu, S., Kawai, R., Kitaoka, M., Igarashi, K., and Samejima, M. (2009) Crystal structure of glycoside hydrolase family 55 β-1,3-glucanase from the basidiomycete Phanerochaete chrysosporium. J. Biol. Chem. 284, 10100-10109). Here, we present high resolution crystal structures of bacterial SacteLam55A from the highly cellulolytic Streptomyces sp. SirexAA-E with bound substrates and product. These structures, along with mutagenesis and kinetic studies, implicate Glu-502 as the catalytic acid (as proposed earlier for Glu-663 in PcLam55A) and a proton relay network of four residues in activating water as the nucleophile. Further, a set of conserved aromatic residues that define the active site apparently enforce an exo-glucanase reactivity as demonstrated by exhaustive hydrolysis reactions with purified laminarioligosaccharides. Two additional aromatic residues that line the substrate-binding channel show substrate-dependent conformational flexibility that may promote processive reactivity of the bound oligosaccharide in the bacterial enzymes. Gene synthesis carried out on 30% of the GH55 family gave 34 active enzymes (19% functional coverage of the nonredundant members of GH55). These active enzymes reacted with only laminarin from a panel of 10 different soluble and insoluble polysaccharides and displayed a broad range of specific activities and optima for pH and temperature. Application of this experimental method provides a new, systematic way to annotate glycoside hydrolase phylogenetic space for functional properties.
genomics, hydrolase, X-ray crystallography, β-1, Proteomics, glycoside hydrolase, 3-glucanase, cell-free translation, exo-glucanase, GH55
Structure type: homopolymer ; n=100
Location inside paper: p. 11820, column 1, paragraph 4
Trivial name: pustulan
Compound class: glucan
Contained glycoepitopes: IEDB_135614,IEDB_141806,IEDB_142488,IEDB_146664,IEDB_241101,IEDB_983931,SB_192
Methods: enzymatic treatments
Enzymes that release or process the structure: GH55
Related record ID(s): 50093
NCBI Taxonomy refs (TaxIDs): 136370Reference(s) to other database(s): GTC:G26777BZ
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There is only one chemically distinct structure:
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