1dlg
From Proteopedia
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CRYSTAL STRUCTURE OF THE C115S ENTEROBACTER CLOACAE MURA IN THE UN-LIGANDED STATE
Overview
The induced-fit mechanism in Enterobacter cloacae MurA has been, investigated by kinetic studies and X-ray crystallography. The antibiotic, fosfomycin, an irreversible inhibitor of MurA, induced a structural change, in UDP-N-acetylglucosamine (UDPGlcNAc)-liganded enzyme with a time, dependence similar to that observed for the inactivation progress. The, mechanism of action of fosfomycin on MurA appeared to be of the, bimolecular type, the overall rate constants of inactivation and, structural change being = 104 M(-1) s(-1) and = 85 M(-1) s(-1), respectively. Fosfomycin as well as the second MurA substrate, phosphoenolpyruvate (PEP), are known to interact with the side chain of, Cys115. Like wild-type MurA, the catalytically inactive single-site mutant, protein Cys115Ser structurally interacted with UDPGlcNAc in a rapidly, reversible reaction. However, in contrast to wild-type enzyme, binding of, PEP to mutant protein induced a rate-limited, biphasic structural change., Fosfomycin did not affect the structure of the mutant protein. The crystal, structure of unliganded Cys115Ser MurA at 1.9 A resolution revealed that, the overall conformation of the loop comprising residues 112-121 is not, influenced by the mutation. However, other than Cys115 in wild-type MurA, Ser115 exhibits two distinct side-chain conformations. A detailed view on, the loop revealed the existence of an elaborate hydrogen-bonding network, mainly supplied by water molecules, presumably stabilizing its, conformation in the unliganded state. The comparison between the known, crystal structures of MurA, together with the kinetic data obtained, suggest intermediate conformational states in the MurA reaction, in which, the loop undergoes multiple structural changes upon ligand binding.
About this Structure
1DLG is a Single protein structure of sequence from Enterobacter cloacae with PO4 and AMC as ligands. Active as UDP-N-acetylglucosamine 1-carboxyvinyltransferase, with EC number 2.5.1.7 Full crystallographic information is available from OCA.
Reference
Role of the loop containing residue 115 in the induced-fit mechanism of the bacterial cell wall biosynthetic enzyme MurA., Schonbrunn E, Eschenburg S, Krekel F, Luger K, Amrhein N, Biochemistry. 2000 Mar 7;39(9):2164-73. PMID:10694381
Page seeded by OCA on Tue Nov 20 13:23:06 2007
