1RDX

R-STATE STRUCTURE OF THE ARG 243 TO ALA MUTANT OF PIG KIDNEY FRUCTOSE 1,6-BISPHOSPHATASE EXPRESSED IN E. COLI

Summary for 1RDX

• Entry DOI: 10.2210/pdb1rdx/pdb
• Descriptor: FRUCTOSE 1,6-BISPHOSPHATASE, 6-O-phosphono-beta-D-fructofuranose (3 entities in total)
• Functional Keywords: hydrolase r243a mutant in the r-state, hydrolase
• Biological source: Sus scrofa (pig)
• Total number of polymer chains: 2
• Total formula weight: 73754.57

Authors

Stec, B.,Abraham, R.,Giroux, E.,Kantrowitz, E.R. (deposition date: 1996-05-17, release date: 1997-01-11, Last modification date: 2024-02-14)

Primary citation

Stec, B.,Abraham, R.,Giroux, E.,Kantrowitz, E.R.
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.
Protein Sci., 5:1541-1553, 1996

PubMed Abstract: 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.

PubMed: 8844845

Experimental method

X-RAY DIFFRACTION (2.75 Å)