2dgl
From Proteopedia
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Crystal structure of Escherichia coli GadB in complex with bromide
Overview
Escherichia coli and other enterobacteria exploit the H+ -consuming, reaction catalysed by glutamate decarboxylase to survive the stomach, acidity before reaching the intestine. Here we show that chloride, extremely abundant in gastric secretions, is an allosteric activator, producing a 10-fold increase in the decarboxylase activity at pH 5.6., Cooperativity and sensitivity to chloride were lost when the N-terminal 14, residues, involved in the formation of two triple-helix bundles, were, deleted by mutagenesis. X-ray structures, obtained in the presence of the, substrate analogue acetate, identified halide-binding sites at the base of, each N-terminal helix, showed how halide binding is responsible for bundle, stability and demonstrated that the interconversion between active and, inactive forms of the enzyme is a stepwise process. We also discovered an, entirely novel structure of the cofactor pyridoxal 5'-phosphate (aldamine), to be responsible for the reversibly inactivated enzyme. Our results link, the entry of chloride ions, via the H+/Cl- exchange activities of ClC-ec1, to the trigger of the acid stress response in the cell when the, intracellular proton concentration has not yet reached fatal values.
About this Structure
2DGL is a Single protein structure of sequence from Escherichia coli with BR, PLP and ACY as ligands. Active as Glutamate decarboxylase, with EC number 4.1.1.15 Full crystallographic information is available from OCA.
Reference
Escherichia coli acid resistance: pH-sensing, activation by chloride and autoinhibition in GadB., Gut H, Pennacchietti E, John RA, Bossa F, Capitani G, De Biase D, Grutter MG, EMBO J. 2006 Jun 7;25(11):2643-51. Epub 2006 May 4. PMID:16675957
Page seeded by OCA on Wed Nov 21 09:36:16 2007
