Crystal structure of fructose-1,6-bisphosphatase complexed with fructose 2,6-bisphosphate, AMP, and Zn2+ at 2.0-A resolution: aspects of synergism between inhibitors.
The crystal structure of fructose-1,6-bisphosphatase (Fru-1,6-Pase; EC 3.1.3.11) complexed with Zn2+ and two allosteric regulators, AMP and fructose 2,6-bisphosphate (Fru-2,6-P2) has been determined at 2.0-A resolution. In the refined model, the crystallographic R factor is 0.189 with rms deviations of 0.014 A and 2.8 degrees from ideal geometries for bond lengths and bond angles, respectively. A 15 degrees rotation is observed between the upper dimer C1C2 and the lower dimer C3C4 relative to the R-form structure (fructose 6-phosphate complex), consistent with that expected from a T-form structure. The major difference between the structure of the previously determined Fru-2,6-P2 complex (R form) and that of the current quaternary T-form complex lies in the active site domain. A zinc binding site distinct from the three binding sites established earlier was identified within each monomer. Helix H4 (residues 123-127) was found to be better defined than in previously studied ligated Fru-1,6-Pase structures. Interactions between monomers in the active site domain were found involving H4 residues from one monomer and residues Tyr-258 and Arg-243 from the adjacent monomer. Cooperativity between AMP and Fru-2,6-P2 in signal transmission probably involves the following features: an AMP site, the adjacent B3 strand (residues 113-118), the metal site, the immediate active site, the short helix H4 (residues 123-127), and Tyr-258 and Arg-243 from the adjacent monomer within the upper (or lower) dimer. The closest distance between the immediate active site and that on the adjacent monomer is only 5 A. Thus, the involvement of H4 in signal transmission adds another important pathway to the scheme of the allosteric mechanism of Fru-1,6-Pase.
Xue
Y
Y
Gibbs Chemical Laboratory, Harvard University, Cambridge, MA 02138.
Huang
S
S
Liang
J Y
JY
Zhang
Y
Y
Lipscomb
W N
WN
D000249:Adenosine Monophosphate / Q000037:antagonists & inhibitors / Q000737:chemistry; D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004357:Drug Synergism; D006597:Fructose-Bisphosphatase / Q000037:antagonists & inhibitors / Q000648:ultrastructure*; D005635:Fructosediphosphates / Q000737:chemistry / Q000494:pharmacology; D066298:In Vitro Techniques; D008667:Metalloproteins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D013552:Swine; D015032:Zinc / Q000737:chemistry
D005635:Fructosediphosphates; D008667:Metalloproteins; D000249:Adenosine Monophosphate; D006597:Fructose-Bisphosphatase; D015032:Zinc