3rgg

Crystal structure of Treponema denticola PurE bound to AIR

spinqualitylabelsall models 3rgg, resolution 1.82Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3rgg is a 4 chain structure with sequence from Treponema denticola. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.82Å Ligands: AIR, CXM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PURE_TREDE Catalyzes the reversible conversion of 5-aminoimidazole ribonucleotide (AIR) and CO(2) to 4-carboxy-5-aminoimidazole ribonucleotide (CAIR). Does not accept N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) as a substrate. Publication Abstract from PubMed De novo purine biosynthesis proceeds by two divergent paths. In bacteria, yeasts, and plants, 5-aminoimidazole ribonucleotide (AIR) is converted to 4-carboxy-AIR (CAIR) by two enzymes: N(5)-carboxy-AIR (N(5)-CAIR) synthetase (PurK) and N(5)-CAIR mutase (class I PurE). In animals, the conversion of AIR to CAIR requires a single enzyme, AIR carboxylase (class II PurE). The CAIR carboxylate derives from bicarbonate or CO(2), respectively. Class I PurE is a promising antimicrobial target. Class I and class II PurEs are mechanistically related but bind different substrates. The spirochete dental pathogen Treponema denticola lacks a purK gene and contains a class II purE gene, the hallmarks of CO(2)-dependent CAIR synthesis. We demonstrate that T. denticola PurE (TdPurE) is AIR carboxylase, the first example of a prokaryotic class II PurE. Steady-state and pre-steady-state experiments show that TdPurE binds AIR and CO(2) but not N(5)-CAIR. Crystal structures of TdPurE alone and in complex with AIR show a conformational change in the key active site His40 residue that is not observed for class I PurEs. A contact between the AIR phosphate and a differentially conserved residue (TdPurE Lys41) enforces different AIR conformations in each PurE class. As a consequence, the TdPurE.AIR complex contains a portal that appears to allow the CO(2) substrate to enter the active site. In the human pathogen T. denticola, purine biosynthesis should depend on available CO(2) levels. Because spirochetes lack carbonic anhydrase, the corresponding reduction in bicarbonate demand may confer a selective advantage. Treponema denticola PurE Is a Bacterial AIR Carboxylase.,Tranchimand S, Starks CM, Mathews II, Hockings SC, Kappock TJ Biochemistry. 2011 May 6. PMID:21548610 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Phosphoribosylaminoimidazole carboxylase 3D structures

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