4irn

Crystal Structure of the Prolyl Acyl Carrier Protein Oxidase AnaB

spinqualitylabelsall models 4irn, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4irn is a 8 chain structure with sequence from Kamptonema sp. PCC 6506. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: FAD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function C4NCB7_9CYAN Publication Abstract from PubMed Anatoxin-a and homoanatoxin-a are two potent cyanobacterial neurotoxins biosynthesized from L-proline by a short pathway involving polyketide synthases. Proline is first loaded onto AnaD, an acyl carrier protein, and prolyl-AnaD is then oxidized to 1-pyrroline-5-carboxyl-AnaD by a flavoprotein, AnaB. Three polyketide synthases then transform this imine into anatoxin-a or homoanatoxin-a. AnaB was crystallized in its holo form and its three-dimensional structure was determined by X-ray diffraction at 2.8 A resolution. AnaB is a homotetramer and its fold is very similar to that of the acyl-CoA dehydrogenases (ACADs). The active-site base of AnaB, Glu244, superimposed very well with that of human isovaleryl-CoA dehydrogenase, confirming previous site-directed mutagenesis experiments and mechanistic proposals. The substrate-binding site of AnaB is small and is likely to be fitted for the pyrrolidine ring of proline. However, in contrast to ACADs, which use an electron-transport protein, AnaB uses molecular oxygen as the electron acceptor, as in acyl-CoA oxidases. Calculation of the solvent-accessible surface area around the FAD in AnaB and in several homologues showed that it is significantly larger in AnaB than in its homologues. A protonated histidine near the FAD in AnaB is likely to participate in oxygen activation. Furthermore, an array of water molecules detected in the AnaB structure suggests a possible path for molecular oxygen towards FAD. This is consistent with AnaB being an oxidase rather than a dehydrogenase. The structure of AnaB is the first to be described for a prolyl-ACP oxidase and it will contribute to defining the structural basis responsible for oxygen reactivity in flavoenzymes. Structure of the prolyl-acyl carrier protein oxidase involved in the biosynthesis of the cyanotoxin anatoxin-a.,Moncoq K, Regad L, Mann S, Mejean A, Ploux O Acta Crystallogr D Biol Crystallogr. 2013 Dec;69(Pt 12):2340-52. doi:, 10.1107/S0907444913021859. Epub 2013 Nov 19. PMID:24311576 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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