1m1b
From Proteopedia
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Crystal Structure of Phosphoenolpyruvate Mutase Complexed with Sulfopyruvate
Overview
The crystal structure of PEP mutase from Mytilus edulis in complex with a, substrate-analogue inhibitor, sulfopyruvate S-pyr (K(i) = 22 microM), has, been determined at 2.25 A resolution. Mg(II)-S-pyr binds in the alpha/beta, barrel's central channel, at the C-termini of the beta-strands. The, binding mode of S-pyr's pyruvyl moiety resembles the binding mode of, oxalate seen earlier. The location of the sulfo group of S-pyr is, postulated to mimic the phosphonyl group of the product phosphonopyruvate, (P-pyr). This sulfo group interacts with the guanidinium group of Arg159, but it is not aligned for nucleopilic attack by neighboring basic amino, side chains. Kinetic analysis of site directed mutants, probing the key, active site residues Asp58, Arg159, Asn122, and His190 correlate well with, the structural information. The results presented here rule out a, phosphoryl transfer mechanism involving a double displacement, and suggest, instead that PEP mutase catalysis proceeds via a dissociative mechanism in, which the pyruvyl C(3) adds to the same face of the phosphorus from which, the C(2)O departs. We propose that Arg159 and His190 serve to hold the, phosphoryl/metaphosphate/phosphonyl group stationary along the reaction, pathway, while the pyruvyl C(1)-C(2) bond rotates upon formation of the, metaphosphate. In agreement with published data, the phosphoryl group, transfer occurs on the Si-face of PEP with retention of configuration at, phosphorus.
About this Structure
1M1B is a Single protein structure of sequence from Mytilus edulis with MG and SPV as ligands. Active as Phosphoenolpyruvate mutase, with EC number 5.4.2.9 Full crystallographic information is available from OCA.
Reference
Dissociative phosphoryl transfer in PEP mutase catalysis: structure of the enzyme/sulfopyruvate complex and kinetic properties of mutants., Liu S, Lu Z, Jia Y, Dunaway-Mariano D, Herzberg O, Biochemistry. 2002 Aug 13;41(32):10270-6. PMID:12162742
Page seeded by OCA on Tue Nov 20 21:03:26 2007
