1xef
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(New page: 200px<br /><applet load="1xef" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xef, resolution 2.50Å" /> '''Crystal structure of...)
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Revision as of 03:54, 21 November 2007
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Crystal structure of the ATP/Mg2+ bound composite dimer of HlyB-NBD
Overview
The ABC transporter HlyB is a central element of the HlyA secretion, machinery, a paradigm of Type I secretion. Here, we describe the crystal, structure of the HlyB-NBD (nucleotide-binding domain) with H662 replaced, by Ala in complex with ATP/Mg2+. The dimer shows a composite architecture, in which two intact ATP molecules are bound at the interface of the Walker, A motif and the C-loop, provided by the two monomers. ATPase measurements, confirm that H662 is essential for activity. Based on these data, we, propose a model in which E631 and H662, highly conserved among ABC, transporters, form a catalytic dyad. Here, H662 acts as a 'linchpin', holding together all required parts of a complicated network of, interactions between ATP, water molecules, Mg2+, and amino acids both in, cis and trans, necessary for intermonomer communication. Based on, biochemical experiments, we discuss the hypothesis that substrate-assisted, catalysis, rather than general base catalysis might operate in, ABC-ATPases.
About this Structure
1XEF is a Single protein structure of sequence from Escherichia coli with MG and ATP as ligands. Full crystallographic information is available from OCA.
Reference
H662 is the linchpin of ATP hydrolysis in the nucleotide-binding domain of the ABC transporter HlyB., Zaitseva J, Jenewein S, Jumpertz T, Holland IB, Schmitt L, EMBO J. 2005 Jun 1;24(11):1901-10. Epub 2005 May 12. PMID:15889153
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