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| [[Image:2z43.jpg|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2z43| PDB=2z43 | SCENE= }} | | {{STRUCTURE_2z43| PDB=2z43 | SCENE= }} |
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| '''Structure of a twinned crystal of RadA'''
| | ===Structure of a twinned crystal of RadA=== |
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| ==Overview==
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| RecA family proteins engage in an ATP-dependent DNA strand exchange reaction that includes a ssDNA nucleoprotein helical filament and a homologous dsDNA sequence. In spite of more than 20 years of efforts, the molecular mechanism of homology pairing and strand exchange is still not fully understood. Here we report a crystal structure of Sulfolobus solfataricus RadA overwound right-handed filament with three monomers per helical pitch. This structure reveals conformational details of the first ssDNA binding disordered loop (denoted L1 motif) and the dsDNA binding N-terminal domain (NTD). L1 and NTD together form an outwardly open palm structure on the outer surface of the helical filament. Inside this palm structure, five conserved basic amino acid residues (K27, K60, R117, R223 and R229) surround a 25 A pocket that is wide enough to accommodate anionic ssDNA, dsDNA or both. Biochemical analyses demonstrate that these five positively charged residues are essential for DNA binding and for RadA-catalyzed D-loop formation. We suggest that the overwound right-handed RadA filament represents a functional conformation in the homology search and pairing reaction. A new structural model is proposed for the homologous interactions between a RadA-ssDNA nucleoprotein filament and its dsDNA target.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17848989}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17848989 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17848989}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Reca]] | | [[Category: Reca]] |
| [[Category: Recombination]] | | [[Category: Recombination]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 19:56:03 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 00:34:55 2008'' |
