The reaction of phosphohexomutase from Pseudomonas aeruginosa: structural insights into a simple processive enzyme

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-bis...

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Bibliographic Details
Published in:The Journal of biological chemistry 2006-06, Vol.281 (22), p.15564-15571
Main Authors: Regni, Catherine, Schramm, Andrew M, Beamer, Lesa J
Format: Article
Language:English
Subjects:
Catalysis
Catalytic Domain - genetics
Crystallography, X-Ray
Glucose-6-Phosphate - analogs & derivatives
Glucose-6-Phosphate - metabolism
Hydrogen Bonding
Kinetics
Models, Biological
Models, Molecular
Mutagenesis, Site-Directed
Phosphoglucomutase - chemistry
Phosphoglucomutase - genetics
Phosphoglucomutase - metabolism
Phosphotransferases (Phosphomutases) - chemistry
Phosphotransferases (Phosphomutases) - genetics
Phosphotransferases (Phosphomutases) - metabolism
Protein Conformation
Pseudomonas aeruginosa
Pseudomonas aeruginosa - enzymology
Pseudomonas aeruginosa - genetics
Recombinant Proteins - chemistry
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
Static Electricity
Substrate Specificity
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Summary: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.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M600590200