1nnr
From Proteopedia
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Crystal structure of a probable fosfomycin resistance protein (PA1129) from Pseudomonas aeruginosa with sulfate present in the active site
Overview
Fosfomycin [(1R,2S)-epoxypropylphosphonic acid] is a simple phosphonate, found to have antibacterial activity against both Gram-positive and, Gram-negative microorganisms. Early resistance to the clinical use of the, antibiotic was linked to a plasmid-encoded resistance protein, FosA, that, catalyzes the addition of glutathione to the oxirane ring, rendering the, antibiotic inactive. Subsequent studies led to the discovery of a, genomically encoded homologue in the pathogen Pseudomonas aeruginosa. The, proteins are Mn(II)-dependent enzymes where the metal is proposed to act, as a Lewis acid stabilizing the negative charge that develops on the, oxirane oxygen in the transition state. Several simple phosphonates, including the antiviral compound phosphonoformate (K(i) = 0.4 +/- 0.1, microM, K(d) approximately 0.2 microM), are shown to be inhibitors of, FosA. The crystal structure of FosA from P. aeruginosa with, phosphonoformate bound in the active site has been determined at 0.95 A, resolution and reveals that the inhibitor forms a five-coordinate complex, with the Mn(II) center with a geometry similar to that proposed for the, transition state of the reaction. Binding studies show that, phosphonoformate has a near-diffusion-controlled on rate (k(on), approximately 10(7)-10(8) M(-1) s(-1)) and an off rate (k(off) = 5 s(-1)), that is slower than that for fosfomycin (k(off) = 30 s(-1)). Taken, together, these data suggest that the FosA-catalyzed reaction has a very, early transition state and phosphonoformate acts as a minimal transition, state analogue inhibitor.
About this Structure
1NNR is a Single protein structure of sequence from Pseudomonas aeruginosa pao1 with MN and SO4 as ligands. Active as Glutathione transferase, with EC number 2.5.1.18 Full crystallographic information is available from OCA.
Reference
Phosphonoformate: a minimal transition state analogue inhibitor of the fosfomycin resistance protein, FosA., Rigsby RE, Rife CL, Fillgrove KL, Newcomer ME, Armstrong RN, Biochemistry. 2004 Nov 2;43(43):13666-73. PMID:15504029
Page seeded by OCA on Tue Nov 20 22:24:53 2007
