3gd9
Crystal structure of laminaripentaose-producing beta-1,3-glucanase in complex with laminaritetraose
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedLaminaripentaose-producing beta-1,3-glucanase (LPHase), a member of glycoside hydrolase family 64, cleaves a long-chain polysaccharide beta-1,3-glucan into specific pentasaccharide oligomers. The crystal structure of LPHase from Streptomyces matensis DIC-108 was solved to 1.62 A resolution using multiple-wavelength anomalous dispersion methods. The LPHase structure reveals a novel crescent-like fold; it consists of a barrel domain and a mixed (alpha/beta) domain, forming a wide-open groove between the two domains. The liganded crystal structure was also solved to 1.80 A, showing limited conformational changes. Within the wide groove, a laminaritetraose molecule is found to sit in an electronegatively charged central region and is proximal to several conserved residues including two carboxylates (Glu(154) and Asp(170)) and four other sugar-binding residues (Thr(156), Asn(158), Trp(163), and Thr(167)). Molecular modeling using a laminarihexaose as a substrate suggests roles for Glu(154) and Asp(170) as acid and base catalysts, respectively, whereas the side chains of Thr(156), Asn(158), and Trp(163) demarcate subsite +5. Site-directed mutagenesis of Glu(154) and Asp(170) confirms that both carboxylates are essential for catalysis. Together, our results suggest that LPHase uses a direct displacement mechanism involving Glu(154) and Asp(170) to cleave a beta-1,3-glucan into specific alpha-pentasaccharide oligomers. Structure, mechanistic action, and essential residues of a GH-64 enzyme, laminaripentaose-producing beta-1,3-glucanase.,Wu HM, Liu SW, Hsu MT, Hung CL, Lai CC, Cheng WC, Wang HJ, Li YK, Wang WC J Biol Chem. 2009 Sep 25;284(39):26708-15. Epub 2009 Jul 29. PMID:19640850[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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