title: DNA-strand exchange promoted by RecA protein in the absence of ATP: implications for the mechanism of energy transduction in protein-promoted nucleic acid transactions.
abstract: DNA-strand exchange promoted by Escherichia coli RecA protein normally requires the presence of ATP and is accompanied by ATP hydrolysis, thereby implying a need for ATP hydrolysis. Previously, ATP hydrolysis was shown not to be required; here we demonstrate furthermore that a nucleoside triphosphate cofactor is not required for DNA-strand exchange. A gratuitous allosteric effector consisting of the noncovalent complex of ADP and aluminum fluoride, ADP.AIF4-, can both induce the high-affinity DNA-binding state of RecA protein and support the homologous pairing and exchange of up to 800-900 bp of DNA. These results demonstrate that induction of the functionally active, high-affinity DNA-binding state of RecA protein is needed for RecA protein-promoted DNA-strand exchange and that there is no requirement for a high-energy nucleotide cofactor for the exchange of DNA strands. Consequently, the free energy needed to activate the DNA substrates for DNA-strand exchange is not derived from ATP hydrolysis. Instead, the needed free energy is derived from ligand binding and is transduced to the DNA via the associated ligand-induced structural transitions of the RecA protein-DNA complex; ATP hydrolysis simply destroys the effector ligand. This concept has general applicability to the mechanism of energy transduction by proteins.
authors.affiliation: Division of Biological Sciences, University of California, Davis 95616, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Kowalczykowski
authors.forename: R A
authors.initials: RA
authors.lastname: Krupp
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D017607:Aluminum Compounds / Q000378:metabolism / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D004734:Energy Metabolism; D005459:Fluorides / Q000378:metabolism / Q000494:pharmacology; D008957:Models, Genetic; D009692:Nucleic Acid Heteroduplexes / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011938:Rec A Recombinases / Q000187:drug effects / Q000378:metabolism*; D011995:Recombination, Genetic / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D017607:Aluminum Compounds; D004268:DNA-Binding Proteins; D009692:Nucleic Acid Heteroduplexes; C050992:tetrafluoroaluminate; D012965:Sodium Chloride; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011938:Rec A Recombinases; D005459:Fluorides