title: Elastic behavior of RecA-DNA helical filaments.
abstract: Escherichia coli RecA protein forms a right-handed helical filament with DNA molecules and has an ATP-dependent activity that exchanges homologous strands between single-stranded DNA (ssDNA) and duplex DNA. We show that the RecA-ssDNA filamentous complex is an elastic helical molecule whose length is controlled by the binding and release of nucleotide cofactors. RecA-ssDNA filaments were fluorescently labelled and attached to a glass surface inside a flow chamber. When the chamber solution was replaced by a buffer solution without nucleotide cofactors, the RecA-ssDNA filament rapidly contracted approximately 0.68-fold with partial filament dissociation. The contracted filament elongated up to 1.25-fold when a buffer solution containing ATPgammaS was injected, and elongated up to 1.17-fold when a buffer solution containing ATP or dATP was injected. This contraction-elongation behavior was able to be repeated by the successive injection of dATP and non-nucleotide buffers. We propose that this elastic motion couples to the elastic motion and/or the twisting rotation of DNA strands within the filament by adjusting their helical phases.
authors.affiliation: Yashima Super-structured Helix Project, ERATO, Japan Science and Technology Agency, 101 Creation Core Nagoya, 2266-22 Anagahora, Shimoshidami, Nagoya 463-0003, Japan. nishinak@yp-jst.jp
authors.forename: Taro
authors.initials: T
authors.lastname: Nishinaka
authors.forename: Yuko
authors.initials: Y
authors.lastname: Doi
authors.forename: Reiko
authors.initials: R
authors.lastname: Hara
authors.forename: Eiji
authors.initials: E
authors.lastname: Yashima
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000737:chemistry; D002021:Buffers; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D003838:Deoxyadenine Nucleotides / Q000737:chemistry; D004548:Elasticity; D029968:Escherichia coli Proteins / Q000737:chemistry*; D008954:Models, Biological; D011938:Rec A Recombinases / Q000737:chemistry*
chemical_list: D002021:Buffers; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D003838:Deoxyadenine Nucleotides; D029968:Escherichia coli Proteins; C022571:adenosine 5'-O-(3-thiotriphosphate); D000255:Adenosine Triphosphate; D011938:Rec A Recombinases; C026600:2'-deoxyadenosine triphosphate