Crystallographic evidence for the action of potassium, thallium, and lithium ions on fructose-1,6-bisphosphatase.Villeret, V., Huang, S., Fromm, H.J., Lipscomb, W.N.
(1995) Proc.Natl.Acad.Sci.USA 92: 8916-8920
- PubMed: 7568043
- Primary Citation of Related Structures:  1FPI, 1FPJ, 1FPK
- PubMed Abstract:
- Structural Aspects of the Allosteric Inhibition of Fructose-1,6-Bisphosphatase by AMP: The Binding of Both the Substrate Analogue 2,5-Anhydro-D-Glucitol 1,6-Bisphosphate and Catalytic Metal Ions Monitored by X-Ray Crystallography
Villeret, V.,Huang, S.,Zhang, Y.,Lipscomb, W.N.
(1995) Biochemistry 34: 4307
- Crystallographic Studies of the Catalytic Mechanism of the Neutral Form of Fructose-1,6-Bisphosphatase
Zhang, Y.,Liang, J.Y.,Huang, S.,Ke, H.,Lipscomb, W.N.
(1993) Biochemistry 32: 1844
- Structural Similarities between Fructose-1,6-Bisphosphatase and Inositol Monophosphatase
Zhang, Y.,Liang, J.Y.,Lipscomb, W.N.
(1993) Biochem.Biophys.Res.Commun. 190: 1080
Fructose-1,6-bisphosphatase (Fru-1,6-Pase; D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 22.214.171.124) requires two divalent metal ions to hydrolyze alpha-D-fructose 1,6-bisphosphate. Although not required for catalysis, monovalent cations modify th ...
Fructose-1,6-bisphosphatase (Fru-1,6-Pase; D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 126.96.36.199) requires two divalent metal ions to hydrolyze alpha-D-fructose 1,6-bisphosphate. Although not required for catalysis, monovalent cations modify the enzyme activity; K+ and Tl+ ions are activators, whereas Li+ ions are inhibitors. Their mechanisms of action are still unknown. We report here crystallographic structures of pig kidney Fru-1,6-Pase complexed with K+, Tl+, or both Tl+ and Li+. In the T form Fru-1,6-Pase complexed with the substrate analogue 2,5-anhydro-D-glucitol 1,6-bisphosphate (AhG-1,6-P2) and Tl+ or K+ ions, three Tl+ or K+ binding sites are found. Site 1 is defined by Glu-97, Asp-118, Asp-121, Glu-280, and a 1-phosphate oxygen of AhG-1,6-P2; site 2 is defined by Glu-97, Glu-98, Asp-118, and Leu-120. Finally, site 3 is defined by Arg-276, Glu-280, and the 1-phosphate group of AhG-1,6-P2. The Tl+ or K+ ions at sites 1 and 2 are very close to the positions previously identified for the divalent metal ions. Site 3 is specific to K+ or Tl+. In the divalent metal ion complexes, site 3 is occupied by the guanidinium group of Arg-276. These observations suggest that Tl+ or K+ ions can substitute for Arg-276 in the active site and polarize the 1-phosphate group, thus facilitating nucleophilic attack on the phosphorus center. In the T form complexed with both Tl+ and Li+ ions, Li+ replaces Tl+ at metal site 1. Inhibition by lithium very likely occurs as it binds to this site, thus retarding turnover or phosphate release. The present study provides a structural basis for a similar mechanism of inhibition for inositol monophosphatase, one of the potential targets of lithium ions in the treatment of manic depression.
Gibbs Chemical Laboratory Harvard University, Cambridge, MA 02138, USA.