1rdx
R-STATE STRUCTURE OF THE ARG 243 TO ALA MUTANT OF PIG KIDNEY FRUCTOSE 1,6-BISPHOSPHATASE EXPRESSED IN E. COLI
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OverviewOverview
The active site of pig kidney fructose-1,6-bisphosphatase (EC 3.1.3.11) is, shared between subunits, Arg-243 of one chain interacting with, fructose-1,6-bisphosphate or fructose-2,6-bisphosphate in the active site, of an adjacent chain. In this study, we present the X-ray structures of, the mutant version of the enzyme with Arg-243 replaced by alanine, crystallized in both T and R allosteric states. Kinetic characteristics of, the altered enzyme showed the magnesium binding and inhibition by AMP, differed slightly; affinity for the substrate fructose-1,6-bisphosphate, was reduced 10-fold and affinity for the inhibitor, fructose-2,6-bisphosphate was reduced 1,000-fold (Giroux E, Williams MK, Kantrowitz ER, 1994, J Biol Chem 269:31404-31409). The X-ray structures, show no major changes in the organization of the active site compared with, wild-type enzyme, and the structures confirm predictions of molecular, dynamics simulations involving Lys-269 and Lys-274. Comparison of two, independent models of the T form structures have revealed small but, significant changes in the conformation of the bound AMP molecules and, small reorganization of the active site correlated with the presence of, the inhibitor. The differences in kinetic properties of the mutant enzyme, indicate the key importance of Arg-243 in the function of, fructose-1,6-bisphosphatase. Calculations using the X-ray structures of, the Arg-243-->Ala enzyme suggest that the role of Arg-243 in the wild-type, enzyme is predominantly electrostatic in nature.
About this StructureAbout this Structure
1RDX is a Single protein structure of sequence from Sus scrofa with F6P as ligand. Active as Fructose-bisphosphatase, with EC number 3.1.3.11 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of the active site mutant (Arg-243-->Ala) in the T and R allosteric states of pig kidney fructose-1,6-bisphosphatase expressed in Escherichia coli., Stec B, Abraham R, Giroux E, Kantrowitz ER, Protein Sci. 1996 Aug;5(8):1541-53. PMID:8844845
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