1xmv: Difference between revisions
New page: left|200px<br /><applet load="1xmv" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xmv, resolution 1.90Å" /> '''"E. Coli RecA in com... |
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[[Image:1xmv.gif|left|200px]]<br /><applet load="1xmv" size=" | [[Image:1xmv.gif|left|200px]]<br /><applet load="1xmv" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1xmv, resolution 1.90Å" /> | caption="1xmv, resolution 1.90Å" /> | ||
'''"E. Coli RecA in complex with MgADP"'''<br /> | '''"E. Coli RecA in complex with MgADP"'''<br /> | ||
==Overview== | ==Overview== | ||
RecA catalyzes the DNA pairing and strand-exchange steps of homologous | RecA catalyzes the DNA pairing and strand-exchange steps of homologous recombination, an important mechanism for repair of double-stranded DNA breaks. The binding of RecA to DNA is modulated by adenosine nucleotides. ATP increases the affinity of RecA for DNA, while ADP decreases the affinity. Previously, the crystal structures of E. coli RecA and its complex with ADP have been determined to resolutions of 2.3 and 3.0 A, respectively, but the model for the RecA-ADP complex did not include magnesium ion or side chains. Here, we have determined the crystal structures of RecA in complex with MgADP and MnAMP-PNP, a nonhydrolyzable analogue of ATP, at resolutions of 1.9 and 2.1 A, respectively. Both crystals grow in the same conditions and have RecA in a right-handed helical form with a pitch of approximately 82 A. The crystal structures show the detailed interactions of RecA with the nucleotide cofactors, including the metal ion and the gamma phosphate of AMP-PNP. There are very few conformational differences between the structures of RecA bound to ADP and AMP-PNP, which differ from uncomplexed RecA only in a slight opening of the P-loop residues 66-73 upon nucleotide binding. To interpret the functional significance of the structure of the MnAMP-PNP complex, a coprotease assay was used to compare the ability of different nucleotides to promote the active, extended conformation of RecA. Whereas ATPgammaS and ADP-AlF(4) facilitate a robust coprotease activity, ADP and AMP-PNP do not activate RecA at all. We conclude that the crystal structure of the RecA-MnAMP-PNP complex represents a preisomerization state of the RecA protein that exists after ATP has bound but before the conformational transition to the active state. | ||
==About this Structure== | ==About this Structure== | ||
1XMV 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 ADP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1XMV 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=ADP:'>ADP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XMV OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Bell, C | [[Category: Bell, C E.]] | ||
[[Category: Xing, X.]] | [[Category: Xing, X.]] | ||
[[Category: ADP]] | [[Category: ADP]] | ||
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[[Category: reca]] | [[Category: reca]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:56:29 2008'' | ||
Revision as of 16:56, 21 February 2008
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"E. Coli RecA in complex with MgADP"
OverviewOverview
RecA catalyzes the DNA pairing and strand-exchange steps of homologous recombination, an important mechanism for repair of double-stranded DNA breaks. The binding of RecA to DNA is modulated by adenosine nucleotides. ATP increases the affinity of RecA for DNA, while ADP decreases the affinity. Previously, the crystal structures of E. coli RecA and its complex with ADP have been determined to resolutions of 2.3 and 3.0 A, respectively, but the model for the RecA-ADP complex did not include magnesium ion or side chains. Here, we have determined the crystal structures of RecA in complex with MgADP and MnAMP-PNP, a nonhydrolyzable analogue of ATP, at resolutions of 1.9 and 2.1 A, respectively. Both crystals grow in the same conditions and have RecA in a right-handed helical form with a pitch of approximately 82 A. The crystal structures show the detailed interactions of RecA with the nucleotide cofactors, including the metal ion and the gamma phosphate of AMP-PNP. There are very few conformational differences between the structures of RecA bound to ADP and AMP-PNP, which differ from uncomplexed RecA only in a slight opening of the P-loop residues 66-73 upon nucleotide binding. To interpret the functional significance of the structure of the MnAMP-PNP complex, a coprotease assay was used to compare the ability of different nucleotides to promote the active, extended conformation of RecA. Whereas ATPgammaS and ADP-AlF(4) facilitate a robust coprotease activity, ADP and AMP-PNP do not activate RecA at all. We conclude that the crystal structure of the RecA-MnAMP-PNP complex represents a preisomerization state of the RecA protein that exists after ATP has bound but before the conformational transition to the active state.
About this StructureAbout this Structure
1XMV is a Single protein structure of sequence from Escherichia coli with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of Escherichia coli RecA in complex with MgADP and MnAMP-PNP., Xing X, Bell CE, Biochemistry. 2004 Dec 28;43(51):16142-52. PMID:15610008
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