4wcj

Structure of IcaB from Ammonifex degensii

spinqualitylabelsall models 4wcj, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4wcj is a 1 chain structure with sequence from Ammonifex degensii KC4. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.7Å Ligands: CL, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function C9RCK9_AMMDK Publication Abstract from PubMed Exopolysaccharides are required for the development and integrity of biofilms produced by a wide variety of bacteria. In staphylococci, partial de-N-acetylation of the exopolysaccharide poly-beta-1,6-N-acetyl-D-glucosamine (PNAG) by the extracellular protein IcaB is required for biofilm formation. To understand the molecular basis for PNAG de-N-acetylation, the structure of IcaB from Ammonifex degensii (AmIcaB) has been determined to 1.7 A resolution. The structure of AmIcaB reveals a (beta/alpha)7 barrel common to the family four carbohydrate esterases (CE4s), with the canonical motifs circularly permuted. The metal dependence of AmIcaB is similar to most CE4s showing the maximum rates of de-N-acetylation with Ni2+, Co2+ and Zn2+. Docking studies with beta-1,6-GlcNAc oligomers and structural comparison to PgaB from Escherichia coli, the Gram-negative homologue of IcaB, we identify R45, Y67, and W180 as key residues for PNAG binding during catalysis. The absence of these residues in PgaB provides a rationale for the requirement of a C-terminal domain for efficient deacetylation of PNAG in Gram-negative species. Mutational analysis of conserved active site residues suggests that IcaB uses an altered catalytic mechanism in comparison to other characterized CE4 members. Furthermore, we identified a conserved surface-exposed hydrophobic loop found only in Gram-positive homologues of IcaB. This loop is required for membrane association, and likely anchors IcaB to the membrane during polysaccharide biosynthesis. The work presented herein will help guide the design of IcaB inhibitors to combat biofilm formation by staphylococci. Structural basis for the de-N-acetylation of poly-beta-1,6-N-acetyl-D-glucosamine in Gram-positive bacteria.,Little DJ, Bamford NC, Podrovskaya V, Robinson H, Nitz M, Howell PL J Biol Chem. 2014 Oct 30. pii: jbc.M114.611400. PMID:25359777 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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