1pmm

From Proteopedia

Revision as of 21:48, 20 November 2007

Crystal structure of Escherichia coli GadB (low pH)

Overview

Glutamate decarboxylase is a vitamin B6-dependent enzyme, which catalyses, the decarboxylation of glutamate to gamma-aminobutyrate. In Escherichia, coli, expression of glutamate decarboxylase (GadB), a 330 kDa hexamer, is, induced to maintain the physiological pH under acidic conditions, like, those of the passage through the stomach en route to the intestine. GadB, together with the antiporter GadC, constitutes the gad acid resistance, system, which confers the ability for bacterial survival for at least 2 h, in a strongly acidic environment. GadB undergoes a pH-dependent, conformational change and exhibits an activity optimum at low pH. We, determined the crystal structures of GadB at acidic and neutral pH. They, reveal the molecular details of the conformational change and the, structural basis for the acidic pH optimum. We demonstrate that the enzyme, is localized exclusively in the cytoplasm at neutral pH, but is recruited, to the membrane when the pH falls. We show by structure-based, site-directed mutagenesis that the triple helix bundle formed by the, N-termini of the protein at acidic pH is the major determinant for this, behaviour.

About this Structure

1PMM is a Single protein structure of sequence from Escherichia coli with PLP and ACY as ligands. Active as Glutamate decarboxylase, with EC number 4.1.1.15 Full crystallographic information is available from OCA.

Reference

Crystal structure and functional analysis of Escherichia coli glutamate decarboxylase., Capitani G, De Biase D, Aurizi C, Gut H, Bossa F, Grutter MG, EMBO J. 2003 Aug 15;22(16):4027-37. PMID:12912902

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