title: Structure of helical RecA-DNA complexes. III. The structural polarity of RecA filaments and functional polarity in the RecA-mediated strand exchange reaction.
abstract: The RecA protein of Escherichia coli has been used in vitro to mediate a strand-exchange reaction between homologous DNA molecules. A three-dimensional reconstruction of a RecA filament on double-stranded DNA has been previously determined from electron micrographs, and the reconstruction displays a clear axial polarity. The RecA-mediated strand-exchange reaction between a double-stranded DNA and a homologous single-stranded DNA that is complexed with a RecA helical polymer proceeds with a known polarity. Using image analysis of electron micrographs, we have determined the relation between the structural polarity of RecA filaments and the 3' and 5' polarity of single-stranded DNA. Thus, the structural polarity of RecA filaments can now be related to the direction in which the RecA-mediated strand-exchange reaction advances along the complexed single-stranded DNA.
mesh_terms: D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D011938:Rec A Recombinases / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D011938:Rec A Recombinases