The reaction of phosphohexomutase from Pseudomonas aeruginosa: structural insights into a simple processive enzyme.
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Regni C, Schramm AM, Beamer LJ
The reaction of phosphohexomutase from Pseudomonas aeruginosa: structural insights into a simple processive enzyme.
J Biol Chem. 2006 Jun 2;281(22):15564-71. Epub 2006 Apr 4.
- PubMed ID
- 16595672 [ View in PubMed]
- Abstract
The enzyme phosphomannomutase/phosphoglucomutase (PMM/PGM) from Pseudomonas aeruginosa catalyzes the reversible conversion of 1-phospho to 6-phospho-sugars. The reaction entails two phosphoryl transfers, with an intervening 180 degrees reorientation of the reaction intermediate (e.g. glucose 1,6-bisphosphate) during catalysis. Reorientation of the intermediate occurs without dissociation from the active site of the enzyme and is, thus, a simple example of processivity, as defined by multiple rounds of catalysis without release of substrate. Structural characterization of two PMM/PGM-intermediate complexes with glucose 1,6-bisphosphate provides new insights into the reaction catalyzed by the enzyme, including the reorientation of the intermediate. Kinetic analyses of site-directed mutants prompted by the structural studies reveal active site residues critical for maintaining association with glucose 1,6-bisphosphate during its unique dynamic reorientation in the active site of PMM/PGM.