3REM: Structure Of The Isochorismate-Pyruvate Lyase From Pseudomonas Aerugionsa With Bound Salicylate And Pyruvate

An isochorismate-pyruvate lyase with adventitious chorismate mutase activity from Pseudomonas aerugionsa (PchB) achieves catalysis of both pericyclic reactions in part by the stabilization of reactive conformations and in part by electrostatic transition-state stabilization. When the active site loop Lys42 is mutated to histidine, the enzyme develops a pH dependence corresponding to a loss of catalytic power upon deprotonation of the histidine. Structural data indicate that the change is not due to changes in active site architecture, but due to the difference in charge at this key site. With loss of the positive charge on the K42H side chain at high pH, the enzyme retains lyase activity at approximately 100-fold lowered catalytic efficiency but loses detectable mutase activity. We propose that both substrate organization and electrostatic transition state stabilization contribute to catalysis. However, the dominant reaction path for catalysis is dependent on reaction conditions, which influence the electrostatic properties of the enzyme active site amino acid side chains.
PDB ID: 3REMDownload
MMDB ID: 93185
PDB Deposition Date: 2011/4/4
Updated in MMDB: 2011/09
Experimental Method:
x-ray diffraction
Resolution: 1.95  Å
Source Organism:
Similar Structures:
Biological Unit for 3REM: dimeric; determined by author and by software (PISA)
Molecular Components in 3REM
Label Count Molecule
Proteins (2 molecules)
Salicylate Biosynthesis Protein Pchb(Gene symbol: pchB)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB