1fpb

Publication Abstract from PubMed

The three-dimensional structure of the complex between fructose 1,6-bisphosphatase (EC 3.1.3.11) and the physiological inhibitor beta-D-fructose 2,6-bisphosphate (Fru-2,6-P2), an analogue of the substrate (fructose 1,6-bisphosphate), has been refined at 2.6-A resolution to a residual error (R) factor of 0.171. The rms deviations are 0.012 A and 2.88 degrees from ideal geometries of bond lengths and angles, respectively. The Fru-2,6-P2 occupies the active sites of both polypeptides C1 and C2 in the crystallographic asymmetric unit in the space group P3(2)21. The furanose and 6-phosphate of Fru-2,6-P2 are located at the fructose 6-phosphate site established earlier, and the 2-phosphate binds to the OH of Ser-124, the NH3+ of Lys-274, and the backbone NH of Gly-122 and Ser-123. Backbone displacements of 1 A occur for residues from Asp-121 to Asn-125. Model building of substrate alpha-D-Fru-1,6-P2 based on the binding structure of Fru-2,6-P2 in the active site shows interactions of the 1-phosphate with the backbone NH of Ser-123 and Ser-124. In the AMP sites, density peaks attributed to Fru-2,6-P2 are seen in C1 (and C4) but not in C2 (and C3). This minor binding of Fru-2,6-P2 to AMP sites partially explains the synergistic interaction between AMP and Fru-2,6-P2 and the protection of the AMP site from acetylation in the presence of Fru-2,6-P2. In the synergistic interaction between AMP and Fru-2,6-P2, inhibition of catalytic metal binding by the presence of Fru-2,6-P2 at the active site, and propagation of structural changes over some 28 A along beta-strand B3 from residues 121 to 125 in the active site to Lys-112 and Tyr-113 in the AMP site, as well as movement of helices across the interdimeric interfaces, may affect AMP binding and the subsequent R-to-T transition. In addition, occupancy of Fru-2,6-P2 at the AMP sites of C1 and C4 may favor binding of AMP to the remaining unoccupied AMP sites and thus promote the accompanying quaternary conformational changes.

Crystal structure of the neutral form of fructose 1,6-bisphosphatase complexed with regulatory inhibitor fructose 2,6-bisphosphate at 2.6-A resolution.,Liang JY, Huang S, Zhang Y, Ke H, Lipscomb WN Proc Natl Acad Sci U S A. 1992 Mar 15;89(6):2404-8. PMID:1312721^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.