1X9H

Crystal structure of phosphoglucose/phosphomannose isomerase from Pyrobaculum aerophilum in complex with fructose 6-phosphate

Summary for 1X9H

• Entry DOI: 10.2210/pdb1x9h/pdb
• Related: 1TZB 1TZC 1X9I
• Descriptor: glucose-6-phosphate isomerase, SULFATE ION, FRUCTOSE -6-PHOSPHATE, ... (5 entities in total)
• Functional Keywords: enzyme, crenarchaeon, hyperthermophile, pgi superfamily, fructose 6-phosphate, isomerase
• Biological source: Pyrobaculum aerophilum
• Total number of polymer chains: 2
• Total formula weight: 68550.74

Authors

Swan, M.K.,Hansen, T.,Schoenheit, P.,Davies, C. (deposition date: 2004-08-21, release date: 2004-12-07, Last modification date: 2023-08-23)

Primary citation

Swan, M.K.,Hansen, T.,Schoenheit, P.,Davies, C.
Structural basis for phosphomannose isomerase activity in phosphoglucose isomerase from Pyrobaculum aerophilum: a subtle difference between distantly related enzymes.
Biochemistry, 43:14088-14095, 2004

PubMed Abstract: The crystal structure of a dual-specificity phosphoglucose/phosphomannose isomerase from the crenarchaeon Pyrobaculum aerophilum (PaPGI/PMI) has been determined in complex with glucose 6-phosphate at 1.16 A resolution and with fructose 6-phosphate at 1.5 A resolution. Subsequent modeling of mannose 6-phosphate (M6P) into the active site of the enzyme shows that the PMI activity of this enzyme may be due to the additional space imparted by a threonine. In PGIs from bacterial and eukaryotic sources, which cannot use M6P as a substrate, the equivalent residue is a glutamine. The increased space may permit rotation of the C2-C3 bond in M6P to facilitate abstraction of a proton from C2 by Glu203 and, after a further C2-C3 rotation of the resulting cis-enediolate, re-donation of a proton to C1 by the same residue. A proline residue (in place of a glycine in PGI) may also promote PMI activity by positioning the C1-O1 region of M6P. Thus, the PMI reaction in PaPGI/PMI probably uses a cis-enediol mechanism of catalysis, and this activity appears to arise from a subtle difference in the architecture of the enzyme, compared to bacterial and eukaryotic PGIs.

PubMed: 15518558
DOI: 10.1021/bi048608y

Experimental method

X-RAY DIFFRACTION (1.5 Å)