1mb9
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(New page: 200px<br /><applet load="1mb9" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mb9, resolution 2.11Å" /> '''BETA-LACTAM SYNTHETA...)
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Revision as of 19:10, 20 November 2007
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BETA-LACTAM SYNTHETASE COMPLEXED WITH ATP
Overview
The catalytic cycle of the ATP/Mg(2+)-dependent enzyme beta-lactam, synthetase (beta-LS) from Streptomyces clavuligerus has been observed, through a series of x-ray crystallographic snapshots. Chemistry is, initiated by the ordered binding of ATP/Mg(2+) and, N(2)-(carboxyethyl)-l-arginine (CEA) to the apoenzyme. The apo and, ATP/Mg(2+) structures described here, along with the previously described, CEA.alpha,beta-methyleneadenosine 5'-triphosphate (CEA.AMP-CPP)/Mg(2+), structure, illuminate changes in active site geometry that favor, adenylation. In addition, an acyladenylate intermediate has been trapped., The substrate analog N(2)-(carboxymethyl)-l-arginine (CMA) was adenylated, by ATP in the crystal and represents a close structural analog of the, previously proposed CEA-adenylate intermediate. Finally, the structure of, the ternary product complex deoxyguanidinoproclavaminic acid, (DGPC).AMP/PP(i)/Mg(2+) has been determined. The CMA-AMP/PP(i)/Mg(2+) and, DGPC.AMP/PP(i)/Mg(2+) structures reveal interactions in the active site, that facilitate beta-lactam formation. All of the ATP-bound structures, differ from the previously described CEA.AMP-CPP/Mg(2+) structure in that, two Mg(2+) ions are found in the active sites. These Mg(2+) ions play, critical roles in both the adenylation and beta-lactamization reactions.
About this Structure
1MB9 is a Single protein structure of sequence from Streptomyces clavuligerus with MG, ATP, POP and AMP as ligands. Full crystallographic information is available from OCA.
Reference
The catalytic cycle of beta -lactam synthetase observed by x-ray crystallographic snapshots., Miller MT, Bachmann BO, Townsend CA, Rosenzweig AC, Proc Natl Acad Sci U S A. 2002 Nov 12;99(23):14752-7. Epub 2002 Oct 30. PMID:12409610
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