2bem | pdb_00002bem

CRYSTAL STRUCTURE OF THE SERRATIA MARCESCENS CHITIN-BINDING PROTEIN CBP21

spinqualitylabelsall models 2bem, resolution 1.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2bem is a 3 chain structure with sequence from Serratia marcescens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: EDO, NA, SO4 Related: 2ben Resources: FirstGlance, OCA, RCSB, PDBsum 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 PubMed Chitin proteins are commonly found in bacteria that utilize chitin as a source of energy. CBP21 is a chitin-binding protein from Serratia marcescens, a Gram-negative soil bacterium capable of efficient chitin degradation. When grown on chitin, S. marcescens secretes large amounts of CBP21, along with chitin-degrading enzymes. In an attempt to understand the molecular mechanism of CBP21 action, we have determined its crystal structure at 1.55 angstroms resolution. This is the first structure to be solved of a family 33 carbohydrate-binding module. The structure reveals a "budded" fibronectin type III fold consisting of two beta-sheets, arranged as a beta-sheet sandwich, with a 65-residue "bud" consisting of three short helices, located between beta-strands 1 and 2. Remarkably, conserved aromatic residues that have been suggested previously to play a role in chitin binding were mainly found in the interior of the protein, seemingly incapable of interacting with chitin, whereas the structure revealed a surface patch of highly conserved, mainly hydrophilic residues. The roles of six of these conserved surface-exposed residues (Tyr-54, Glu-55, Glu-60, His-114, Asp-182, and Asn-185) were probed by site-directed mutagenesis and subsequent binding studies. All single point mutations lowered the affinity of CBP21 for beta-chitin, as shown by 3-8-fold increases in the apparent binding constant. Thus, binding of CBP21 to chitin seems to be mediated primarily by conserved, solvent-exposed, polar side chains. Crystal structure and binding properties of the Serratia marcescens chitin-binding protein CBP21.,Vaaje-Kolstad G, Houston DR, Riemen AH, Eijsink VG, van Aalten DM J Biol Chem. 2005 Mar 25;280(12):11313-9. Epub 2004 Dec 8. PMID:15590674 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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