3aib | pdb_00003aib

Crystal Structure of Glucansucrase

spinqualitylabelsall models 3aib, resolution 3.09Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3aib is a 8 chain structure with sequence from Streptococcus mutans. The June 2011 RCSB PDB Molecule of the Month feature on Glucansucrase by David Goodsell is 10.2210/rcsb_pdb/mom_2011_6. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, MAL, MES Related: 3aic, 3aie Gene: gtfC, SMU_1005 (Streptococcus mutans) Activity: Dextransucrase, with EC number 2.4.1.5 Resources: FirstGlance, OCA, RCSB, PDBsum Function [GTFC_STRMU] Production of extracellular glucans, that are thought to play a key role in the development of the dental plaque because of their ability to adhere to smooth surfaces and mediate the aggregation of bacterial cells and food debris. Publication Abstract from PubMed Glucansucrase (GSase) from Streptococcus mutans is an essential agent in dental caries pathogenesis. Here, we report the crystal structure of S. mutans glycosyltransferase (GTF-SI), which synthesizes soluble and insoluble glucans and is a glycoside hydrolase (GH) family 70 GSase in the free enzyme form and in complex with acarbose and maltose. Resolution of the GTF-SI structure confirmed that the domain order of GTF-SI is circularly permuted as compared to that of GH family 13 alpha-amylases. As a result, domains A, B and IV of GTF-SI are each composed of two separate polypeptide chains. Structural comparison of GTF-SI and amylosucrase, which is closely related to GH family 13 amylases, indicated that the two enzymes share a similar transglycosylation mechanism via a glycosyl-enzyme intermediate in subsite -1. On the other hand, novel structural features were revealed in subsites +1 and +2 of GTF-SI. Trp517 provided the platform for glycosyl acceptor binding, while Tyr430, Asn481 and Ser589, which are conserved in family 70 enzymes but not in family 13 enzymes, comprised subsite +1. Based on the structure of GTF-SI and amino acid comparison of GTF-SI, GTF-I and GTF-S, Asp593 in GTF-SI appeared to be the most critical point for acceptor sugar orientation, influencing the transglycosylation specificity of GSases, that is, whether they produced insoluble glucan with alpha(1-3) glycosidic linkages or soluble glucan with alpha(1-6) linkages. The structural information derived from the current study should be extremely useful in the design of novel inhibitors that prevent the biofilm formation by GTF-SI. Crystal Structure of Glucansucrase from the Dental Caries Pathogen Streptococcus mutans.,Ito K, Ito S, Shimamura T, Weyand S, Kawarasaki Y, Misaka T, Abe K, Kobayashi T, Cameron AD, Iwata S J Mol Biol. 2011 Feb 25. PMID:21354427 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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