title: Inhibition of recA protein promoted ATP hydrolysis. 2. Longitudinal assembly and disassembly of recA protein filaments mediated by ATP and ADP.
abstract: There are at least two major conformations of recA nucleoprotein filaments formed on poly-(deoxythymidylic acid) [poly(dT)], one stabilized by ATP [or adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S)] and one stabilized by ADP. Assembly of filaments in the ATP conformation is much faster than assembly in the ADP conformation. A third conformation may be present in the absence of nucleotides. The ATP and ADP conformations are mutually exclusive. When a mixture of ATP and ADP is present, recA protein binding is a function of the ADP/ATP ratio. Complete dissociation is observed when the ratio becomes 1.0-1.5. When a mixture of ATP and ADP is present at the beginning of a reaction, a transient phase lasting several minutes is observed in which the system approaches the state characteristic of the new ADP/ATP ratio. This phase is manifested by a lag in ATP hydrolysis when ATP is added to preformed ADP filaments, and by a burst in ATP hydrolysis in all other cases. More than 15 ATPs are hydrolyzed per bound recA monomer during the burst phase. The transient phase reflects an end-dependent disassembly process propagated longitudinally through the filament, rather than a slow conformation change in individual recA monomers or a slow exchange of one nucleotide for the other. The hysteresis exhibited by the system provides a number of insights relevant to the mechanism of recA-mediated DNA strand exchange.
authors: Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison 53706.
authors: J W
authors: JW
authors: Lee
authors: M M
authors: MM
authors: Cox
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D011938:Rec A Recombinases / Q000378:metabolism*
chemical_list: C022571:adenosine 5'-O-(3-thiotriphosphate); D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011938:Rec A Recombinases