4whn

Structure of toxin-activating acyltransferase (TAAT)

spinqualitylabelsall models 4whn, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4whn is a 4 chain structure with sequence from Actinobacillus pleuropneumoniae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.15Å Ligands: CIT Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RTX1C_ACTPL Involved in fatty acylation of the protoxin, thereby converting it to the active toxin. Publication Abstract from PubMed Secreted pore-forming toxins of pathogenic Gram-negative bacteria such as Escherichia coli hemolysin (HlyA) insert into host-cell membranes to subvert signal transduction and induce apoptosis and cell lysis. Unusually, these toxins are synthesized in an inactive form that requires posttranslational activation in the bacterial cytosol. We have previously shown that the activation mechanism is an acylation event directed by a specialized acyl-transferase that uses acyl carrier protein (ACP) to covalently link fatty acids, via an amide bond, to specific internal lysine residues of the protoxin. We now reveal the 2.15-A resolution X-ray structure of the 172-aa ApxC, a toxin-activating acyl-transferase (TAAT) from pathogenic Actinobacillus pleuropneumoniae. This determination shows that bacterial TAATs are a structurally homologous family that, despite indiscernible sequence similarity, form a distinct branch of the Gcn5-like N-acetyl transferase (GNAT) superfamily of enzymes that typically use acyl-CoA to modify diverse bacterial, archaeal, and eukaryotic substrates. A combination of structural analysis, small angle X-ray scattering, mutagenesis, and cross-linking defined the solution state of TAATs, with intermonomer interactions mediated by an N-terminal alpha-helix. Superposition of ApxC with substrate-bound GNATs, and assay of toxin activation and binding of acyl-ACP and protoxin peptide substrates by mutated ApxC variants, indicates the enzyme active site to be a deep surface groove. Structure of a bacterial toxin-activating acyltransferase.,Greene NP, Crow A, Hughes C, Koronakis V Proc Natl Acad Sci U S A. 2015 May 27. pii: 201503832. PMID:26016525 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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