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1yz0
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(New page: 200px<br /><applet load="1yz0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1yz0, resolution 2.07Å" /> '''R-State AMP Complex ...)
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Revision as of 05:01, 21 November 2007
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R-State AMP Complex Reveals Initial Steps of the Quaternary Transition of Fructose-1,6-bisphosphatase
Overview
AMP transforms fructose-1,6-bisphosphatase from its active R-state to its, inactive T-state; however, the mechanism of that transformation is poorly, understood. The mutation of Ala(54) to leucine destabilizes the T-state of, fructose-1,6-bisphosphatase. The mutant enzyme retains wild-type levels of, activity, but the concentration of AMP that causes 50% inhibition, increases 50-fold. In the absence of AMP, the Leu(54) enzyme adopts an, R-state conformation nearly identical to that of the wild-type enzyme. The, mutant enzyme, however, grows in two crystal forms in the presence of, saturating AMP. In one form, the AMP-bound tetramer is in a T-like, conformation, whereas in the other form, the AMP-bound tetramer is in a, R-like conformation. The latter reveals conformational changes in two, helices due to the binding of AMP. Helix H1 moves toward the center of the, tetramer and displaces Ile(10) from a hydrophobic pocket. The displacement, of Ile(10) exposes a hydrophobic surface critical to interactions that, stabilize the T-state. Helix H2 moves away from the center of the, tetramer, breaking hydrogen bonds with a buried loop (residues 187-195) in, an adjacent subunit. The same hydrogen bonds reform but only after the, quaternary transition to the T-state. Proposed here is a model that, accounts for the quaternary transition and cooperativity in the inhibition, of catalysis by AMP.
About this Structure
1YZ0 is a Single protein structure of sequence from Sus scrofa with F6P, MG and AMP as ligands. Active as Fructose-bisphosphatase, with EC number 3.1.3.11 Full crystallographic information is available from OCA.
Reference
R-state AMP complex reveals initial steps of the quaternary transition of fructose-1,6-bisphosphatase., Iancu CV, Mukund S, Fromm HJ, Honzatko RB, J Biol Chem. 2005 May 20;280(20):19737-45. Epub 2005 Mar 14. PMID:15767255
Page seeded by OCA on Wed Nov 21 07:08:46 2007
