2j5v

GLUTAMATE 5-KINASE FROM ESCHERICHIA COLI COMPLEXED WITH GLUTAMYL-5-PHOSPHATE AND PYROGLUTAMIC ACID

spinqualitylabelsall models 2j5v, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2j5v is a 2 chain structure with sequence from "bacillus_coli"_migula_1895 "bacillus coli" migula 1895. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: MG, PCA, RGP, SO4 Related: 2j5t Activity: Glutamate 5-kinase, with EC number 2.7.2.11 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [PROB_ECOLI] Catalyzes the transfer of a phosphate group to glutamate to form L-glutamate 5-phosphate.[HAMAP-Rule:MF_00456] 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 Glutamate 5-kinase (G5K) makes the highly unstable product glutamyl 5-phosphate (G5P) in the initial, controlling step of proline/ornithine synthesis, being feedback-inhibited by proline or ornithine, and causing, when defective, clinical hyperammonaemia. We determined two crystal structures of G5K from Escherichia coli, at 2.9 A and 2.5 A resolution, complexed with glutamate and sulphate, or with G5P, sulphate and the proline analogue 5-oxoproline. E. coli G5K presents a novel tetrameric (dimer of dimers) architecture. Each subunit contains a 257 residue AAK domain, typical of acylphosphate-forming enzymes, with characteristic alpha(3)beta(8)alpha(4) sandwich topology. This domain is responsible for catalysis and proline inhibition, and has a crater on the beta sheet C-edge that hosts the active centre and bound 5-oxoproline. Each subunit contains a 93 residue C-terminal PUA domain, typical of RNA-modifying enzymes, which presents the characteristic beta(5)beta(4) sandwich fold and three alpha helices. The AAK and PUA domains of one subunit associate non-canonically in the dimer with the same domains of the other subunit, leaving a negatively charged hole between them that hosts two Mg ions in one crystal, in line with the G5K requirement for free Mg. The tetramer, formed by two dimers interacting exclusively through their AAK domains, is flat and elongated, and has in each face, pericentrically, two exposed active centres in alternate subunits. This would permit the close apposition of two active centres of bacterial glutamate-5-phosphate reductase (the next enzyme in the proline/ornithine-synthesising route), supporting the postulated channelling of G5P. The structures clarify substrate binding and catalysis, justify the high glutamate specificity, explain the effects of known point mutations, and support the binding of proline near glutamate. Proline binding may trigger the movement of a loop that encircles glutamate, and which participates in a hydrogen bond network connecting active centres, which is possibly involved in the cooperativity for glutamate. A novel two-domain architecture within the amino acid kinase enzyme family revealed by the crystal structure of Escherichia coli glutamate 5-kinase.,Marco-Marin C, Gil-Ortiz F, Perez-Arellano I, Cervera J, Fita I, Rubio V J Mol Biol. 2007 Apr 13;367(5):1431-46. Epub 2007 Feb 3. PMID:17321544 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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