1FS5

A DISCOVERY OF THREE ALTERNATE CONFORMATIONS IN THE ACTIVE SITE OF GLUCOSAMINE-6-PHOSPHATE ISOMERASE

Summary for 1FS5

• Entry DOI: 10.2210/pdb1fs5/pdb
• Related: 1CD5 1D9T 1DEA 1FQO 1FRZ 1HOR 1HOT
• Descriptor: GLUCOSAMINE-6-PHOSPHATE DEAMINASE, 2-acetamido-2-deoxy-6-O-phosphono-alpha-D-glucopyranose, L(+)-TARTARIC ACID, ... (4 entities in total)
• Functional Keywords: allosteric enzyme, entropic effects, aldose-ketose isomerase, multiple conformers, isomerase
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 60376.88

Authors

Rudino-Pinera, E.,Morales-Arrieta, S.,Rojas-Trejo, S.P.,Horjales, E. (deposition date: 2000-09-08, release date: 2002-01-04, Last modification date: 2024-02-07)

Primary citation

Rudino-Pinera, E.,Morales-Arrieta, S.,Rojas-Trejo, S.P.,Horjales, E.
Structural flexibility, an essential component of the allosteric activation in Escherichia coli glucosamine-6-phosphate deaminase.
Acta Crystallogr.,Sect.D, 58:10-20, 2002

PubMed Abstract: A new crystallographic structure of the free active-site R conformer of the allosteric enzyme glucosamine-6-phosphate deaminase from Escherichia coli, coupled with previously reported structures of the T and R conformers, generates a detailed description of the heterotropic allosteric transition in which structural flexibility plays a central role. The T conformer's external zone [Horjales et al. (1999), Structure, 7, 527-536] presents higher B values than in the R conformers. The ligand-free enzyme (T conformer) undergoes an allosteric transition to the free active-site R conformer upon binding of the allosteric activator. This structure shows three alternate conformations of the mobile section of the active-site lid (residues 163-182), in comparison to the high B values for the unique conformation of the T conformer. One of these alternate R conformations corresponds to the active-site lid found when the substrate is bound. The disorder associated with the three alternate conformations can be related to the biological regulation of the K(m) of the enzyme for the reaction, which is metabolically required to maintain adequate concentrations of the activator, which holds the enzyme in its R state. Seven alternate conformations for the active-site lid and three for the C-terminus were refined for the T structure using isotropic B factors. Some of these conformers approach that of the R conformer in geometry. Furthermore, the direction of the atomic vibrations obtained with anisotropic B refinement supports the hypothesis of an oscillating rather than a tense T state. The concerted character of the allosteric transition is also analysed in view of the apparent dynamics of the conformers.

PubMed: 11752775
DOI: 10.1107/S0907444901016699

Experimental method

X-RAY DIFFRACTION (1.73 Å)