1M1B: Crystal Structure Of Phosphoenolpyruvate Mutase Complexed With Sulfopyruvate

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.
PDB ID: 1M1BDownload
MMDB ID: 20495
PDB Deposition Date: 2002/6/18
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 2.25  Å
Source Organism:
Similar Structures:
Biological Unit for 1M1B: tetrameric; determined by author and by software (PISA,PQS)
Molecular Components in 1M1B
Label Count Molecule
Proteins (4 molecules)
Phosphoenolpyruvate Phosphomutase
Molecule annotation
Chemicals (8 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB