2j44
From Proteopedia
Alpha-glucan binding by a streptococcal virulence factor
Structural highlights
FunctionPULA_STRPN Virulence factor (By similarity). Involved in the degradation of glycogen of the mammalian host cells (PubMed:21565699). Hydrolyzes the alpha-1,6-branchpoints of glycogen (PubMed:20497336, PubMed:21565699). Hydrolyzes pullulan. Does not hydrolyze dextran (PubMed:20497336). Binds to mouse lung alveolar type II cells that are rich in glycogen stores. Is an alpha-glucan-specific carbohydrate-binding protein, which binds to amylose (pure alpha-(1,4)-linked glucose), amylopectin (alpha-(1,4)-linked glucose with alpha-(1,6) branch points), pullulan (linear polymer of mixed alpha-(1,4)- and alpha-(1,6)-linked glucose) and glycogen (similar to amylopectin with more frequent alpha-(1,6) branch points) in vitro. Does not bind to dextran (a linear polymer of alpha-(1,6)-linked glucose) (PubMed:17187076).[UniProtKB:A0A0H2ZL64][1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe ability of pathogenic bacteria to recognize host glycans is often essential to their virulence. Here we report structure-function studies of previously uncharacterized glycogen-binding modules in the surface-anchored pullulanases from Streptococcus pneumoniae (SpuA) and Streptococcus pyogenes (PulA). Multivalent binding to glycogen leads to a strong interaction with alveolar type II cells in mouse lung tissue. X-ray crystal structures of the binding modules reveal a novel fusion of tandem modules into single, bivalent functional domains. In addition to indicating a structural basis for multivalent attachment, the structure of the SpuA modules in complex with carbohydrate provides insight into the molecular basis for glycogen specificity. This report provides the first evidence that intracellular lung glycogen may be a novel target of pathogenic streptococci and thus provides a rationale for the identification of the streptococcal alpha-glucan-metabolizing machinery as virulence factors. Identification and structural basis of binding to host lung glycogen by streptococcal virulence factors.,van Bueren AL, Higgins M, Wang D, Burke RD, Boraston AB Nat Struct Mol Biol. 2007 Jan;14(1):76-84. Epub 2006 Dec 24. PMID:17187076[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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