2dgk
From Proteopedia
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| , resolution 1.90Å | |||||||
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| Ligands: | , , | ||||||
| Gene: | gadB (Escherichia coli) | ||||||
| Activity: | Glutamate decarboxylase, with EC number 4.1.1.15 | ||||||
| Related: | 1PMM, 1PMO, 2DGL, 2DGM
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal structure of an N-terminal deletion mutant of Escherichia coli GadB in an autoinhibited state (aldamine)
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
2DGK is a Single protein structure of sequence from Escherichia coli. 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 Mon Mar 31 02:34:22 2008
