2ox3
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(New page: 200px<br /><applet load="2ox3" size="450" color="white" frame="true" align="right" spinBox="true" caption="2ox3, resolution 2.180Å" /> '''R-state, PEP and Fr...)
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Revision as of 11:13, 21 November 2007
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R-state, PEP and Fru-6-P-bound, Escherichia coli fructose-1,6-bisphosphatase
Overview
The enteric bacterium Escherichia coli requires, fructose-1,6-bisphosphatase (FBPase) for growth on gluconeogenic carbon, sources. Constitutive expression of FBPase and, fructose-6-phosphate-1-kinase coupled with the absence of futile cycling, implies an undetermined mechanism of coordinate regulation involving both, enzymes. Tricarboxylic acids and phosphorylated three-carbon carboxylic, acids, all intermediates of glycolysis and the tricarboxylic acid cycle, are shown here to activate E. coli FBPase. The two most potent activators, phosphoenolpyruvate and citrate, bind to the sulfate anion site, revealed, previously in the first crystal structure of the E. coli enzyme. Tetramers, ligated with either phosphoenolpyruvate or citrate, in contrast to the, sulfate-bound structure, are in the canonical R-state of porcine FBPase, but nevertheless retain sterically blocked AMP pockets. At physiologically, relevant concentrations, phosphoenolpyruvate and citrate stabilize an, active tetramer over a less active enzyme form of mass comparable with, that of a dimer. The above implies the conservation of the R-state through, evolution. FBPases of heterotrophic organisms of distantly related, phylogenetic groups retain residues of the allosteric activator site and, in those instances where data are available exhibit activation by, phosphoenolpyruvate. Findings here unify disparate observations regarding, bacterial FBPases, implicating a mechanism of feed-forward activation in, bacterial central metabolism.
About this Structure
2OX3 is a Single protein structure of sequence from Escherichia coli with F6P and PEP as ligands. Active as Fructose-bisphosphatase, with EC number 3.1.3.11 Full crystallographic information is available from OCA.
Reference
Structures of activated fructose-1,6-bisphosphatase from Escherichia coli. Coordinate regulation of bacterial metabolism and the conservation of the R-state., Hines JK, Fromm HJ, Honzatko RB, J Biol Chem. 2007 Apr 20;282(16):11696-704. Epub 2007 Feb 21. PMID:17314096
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