1xef
From Proteopedia
(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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| - | [[Image:1xef.gif|left|200px]]<br /><applet load="1xef" size=" | + | [[Image:1xef.gif|left|200px]]<br /><applet load="1xef" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1xef, resolution 2.50Å" /> | caption="1xef, resolution 2.50Å" /> | ||
'''Crystal structure of the ATP/Mg2+ bound composite dimer of HlyB-NBD'''<br /> | '''Crystal structure of the ATP/Mg2+ bound composite dimer of HlyB-NBD'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The ABC transporter HlyB is a central element of the HlyA secretion | + | 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== | ==About this Structure== | ||
| - | 1XEF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with MG and ATP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1XEF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=ATP:'>ATP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XEF OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Holland, I | + | [[Category: Holland, I B.]] |
[[Category: Jenewein, S.]] | [[Category: Jenewein, S.]] | ||
[[Category: Schmitt, L.]] | [[Category: Schmitt, L.]] | ||
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[[Category: haemolysin b]] | [[Category: haemolysin b]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:53:53 2008'' |
Revision as of 13:53, 21 February 2008
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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 and 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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