title: Cooperative conformational transitions keep RecA filament active during ATPase cycle.
abstract: The active, stretched conformation of the RecA filament bound to single-stranded DNA is required for homologous recombination. During this process, the RecA filament mediates the homology search and base pair exchange with a complementary sequence. Subsequently, the RecA filament dissociates from DNA upon reaction completion. ATP binding and hydrolysis is critical throughout these processes. Little is known about the timescale, order of conversion between different cofactor bound forms during ATP hydrolysis, and the associated changes in filament conformation. We used single-molecule fluorescence techniques to investigate how ATP hydrolysis is coupled with filament dynamics. For the first time, we observed real-time cooperative structural changes within the RecA filament. This cooperativity between neighboring monomers provides a time window for nucleotide cofactor exchange, which keeps the filament in the active conformation amidst continuous cycles of ATP hydrolysis.
authors.affiliation: Department of Physics and Interdisciplinary Program of Integrated Biotechnology, Sogang University , Seoul 121-742, Korea.
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Kaushik
authors.initials: K
authors.lastname: Ragunathan
authors.forename: Jeehae
authors.initials: J
authors.lastname: Park
authors.forename: Chirlmin
authors.initials: C
authors.lastname: Joo
authors.forename: Doseok
authors.initials: D
authors.lastname: Kim
authors.forename: Taekjip
authors.initials: T
authors.lastname: Ha
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006868:Hydrolysis; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D011938:Rec A Recombinases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004277:DNA, Single-Stranded; D000255:Adenosine Triphosphate; D011938:Rec A Recombinases; D000251:Adenosine Triphosphatases