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Lipscomb, Martin; Jones, K G; Ahluwalia, Sonya

doi:10.7748/ns.5.16.41.s39

Cited by 2 publications

(4 citation statements)

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“…Similarily, intermolecular interactions of Asn-142 with Tyr-140 and with Ala-24 are observed in the C1 chain of this F6P structure, but not in the C2 chain. In addition, superposition of C2 over C1 shows a shift of >1 A in the position of the helix H1 (residues [12][13][14][15][16][17][18][19][20][21][22][23][24] (Fig. 6), a shift that may reflect a difference in affinity of the two chains for F6P.…”

Section: A339mentioning

confidence: 99%

“…Three-dimensional structures have been described for the crystals of the unligated Fru-1,6-Pase and an active-site complex (Fru-2,6-P2 or a hydrolyzed product) (14,15), the F6P-AMP-Mg2+ complex (16), and the AMP complex (17). The two T-form structures show AMP binding to the allosteric site, which is about 28 A from the active site of the enzyme, and suggest possible allosteric mechanisms of AMP inhibition (17,18).…”

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confidence: 99%

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Crystal structure of the neutral form of fructose-1,6-bisphosphatase complexed with the product fructose 6-phosphate at 2.1-A resolution.

Zhang

Liang

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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The crystal structure of fructose-1,6-bisphosphatase (EC 3.1.3.11) complexed with the product fructose 6-phosphate (F6P) has been refied at 2.1-A resolution to an R factor of 0.177 with root-mean-square deviations of 0.014 A and 2.9°from the ideal geometries of bond lengths and bond angles, respectively. The secondary structues but not the trace of the unligated enzyme have been slightly revised in the F6P complex at this higher resolution. Helix H4 in the unligated structure has been refined to a helix-like coil, and two very short 310 helices have been found, one in H4 and one in H5. F6P at 10 mM concentration in the absence ofdivalent metals in our study shows major binding at the active site and minor binding at the AMP site. The major site has almost equal full occupancy in the C1 and C2 chains of the crystallographic asymmetric unit, while the minor site shows occupancy only in the C1 chain at about 50%. The electron density in both (2Fo -Fc) and (Fo -Fr) maps calculated by omitting F6P slightly favors the 13 anomer of D-F6P over the a anomer. Possible functions of the active-site residues are discussed, and candidates are suggested for site-directed mutagenesis.Fructose-1,6-bisphosphatase (Fru-1,6-Pase; EC 3.1.3.11), a key regulatory enzyme in gluconeogenesis, catalyzes the hydrolysis of fructose 1,6-bisphosphate (Fru-1,6-P2) to fructose 6-phosphate (F6P) and inorganic phosphate. A divalent metal ion (e.g., Mg2' or Mn2+) is a necessary cofactor for the enzymatic reaction. The catalytic and regulatory properties of the enzyme from various sources have been extensively studied (1-4). Two inhibitors, AMP and fructose 2,6-bisphosphate , control the activity of Fru-1,6-Pase. The inhibition by AMP is allosteric (5). However, controversial views from kinetic experiments suggest that Fru-2,6-P2 binds to the active site (4), to an allosteric site (3), or to both (6). Eight complete amino acid sequences have been reported (7-13). The sequence homology among the mammalian enzymes is >85% in comparison to about 45% homology among all Fru-1,6-Pases.Fru-1,6-Pase is a tetrameric molecule with four identical polypeptide chains that aggregates into a flat hexagonal disk with D2 symmetry (Fig. 1). Three-dimensional structures have been described for the crystals of the unligated Fru-1,6-Pase and an active-site complex (Fru-2,6-P2 or a hydrolyzed product) (14, 15), the F6P-AMP-Mg2+ complex (16), and the AMP complex (17). The two T-form structures show AMP binding to the allosteric site, which is about 28 A from the active site of the enzyme, and suggest possible allosteric mechanisms of AMP inhibition (17, 18).The F6P complex has essentially the same secondary and quaternary structures as the unligated enzyme. Conformations of some loops that have random coil configurations have been repositioned during the refinement of the F6P structure and are described in detail here. t On the basis ofthe structure, a partial list of amino acids that are important for the activity of the enzyme is suggested for site-directed mu...

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Section: A339mentioning

confidence: 99%

mentioning

confidence: 99%

Crystal structure of the neutral form of fructose-1,6-bisphosphatase complexed with the product fructose 6-phosphate at 2.1-A resolution.

Zhang

Liang

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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“…In a previous crystallographic study of Fru-1,6-Pase to which Fru-2,6-P2 was added, the 6-phosphate and furanose groups of Fru-2,6-P2 were found at the same binding position as Fru-6-P in the active site of the Fru-6-P complex (40,42). However, no electron density was detected for the 2-phosphate group of Fru-2,6-P2.…”

mentioning

confidence: 87%

“…However, no electron density was detected for the 2-phosphate group of Fru-2,6-P2. The result was interpreted as being due to disorder of the 2-phosphate group (37,38) or probable hydrolysis of Fru-2,6-P2 to form Fru-6-P and Pi (40,42).…”

mentioning

confidence: 99%

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

Huang

Zhang

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

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The three-dimensional structure of the complex between fructose 1,6-bisphosphatase (EC 3.1.3.11) and the physiological inhibitor 3-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 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 P3221. 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 NH3t 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 a-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 ,3-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.

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Squeaks of approval

Cited by 2 publications

References 0 publications

Crystal structure of the neutral form of fructose-1,6-bisphosphatase complexed with the product fructose 6-phosphate at 2.1-A resolution.

Crystal structure of the neutral form of fructose-1,6-bisphosphatase complexed with the product fructose 6-phosphate at 2.1-A resolution.

Crystal structure of the neutral form of fructose 1,6-bisphosphatase complexed with regulatory inhibitor fructose 2,6-bisphosphate at 2.6-A resolution.

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