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1xms

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[[Image:1xms.gif|left|200px]]
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{{STRUCTURE_1xms| PDB=1xms | SCENE= }}
{{STRUCTURE_1xms| PDB=1xms | SCENE= }}
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'''"E. Coli RecA in complex with MnAMP-PNP"'''
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==="E. Coli RecA in complex with MnAMP-PNP"===
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==Overview==
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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.
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(as it appears on PubMed at http://www.pubmed.gov), where 15610008 is the PubMed ID number.
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{{ABSTRACT_PUBMED_15610008}}
==About this Structure==
==About this Structure==
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[[Category: Homologous recombination]]
[[Category: Homologous recombination]]
[[Category: Reca]]
[[Category: Reca]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:14:03 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 20:58:20 2008''

Revision as of 17:58, 27 July 2008

Image:1xms.png

Template:STRUCTURE 1xms

"E. Coli RecA in complex with MnAMP-PNP"

Template:ABSTRACT PUBMED 15610008

About this Structure

1XMS is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

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

Page seeded by OCA on Sun Jul 27 20:58:20 2008

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