title: Homologous pairing between nucleosome cores on a linear duplex DNA and nucleoprotein filaments of RecA protein-single stranded DNA.
abstract: The ability of E coli recA protein to promote homologous pairing with linear duplex DNA bound to HU protein (Nucleosome cores) was found to be differentially affected. The formation of paranemic joint molecules was not affected whereas the formation of plectomic joint molecules was inhibited from the start of the reaction. The formation of paranemic joint molecules between nucleoprotein filaments of recA protein-circular single stranded DNA and closed circular duplex DNA is believed to generate positive supercoiling in the duplex DNA. We found that the positively superhelical duplex DNA was inert in the formation of joint molecules but could be converted into an active substrate, in situ, by the action of wheat germ topoisomerase I. These observations initiate an understanding of the structural features of E coli chromosome such as DNA supercoiling and nucleosome-like structures in homologous recombination.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore.
authors.forename: K
authors.initials: K
authors.lastname: Muniyappa
authors.forename: J
authors.initials: J
authors.lastname: Ramdas
authors.forename: E
authors.initials: E
authors.lastname: Mythili
authors.forename: S
authors.initials: S
authors.lastname: Galande
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001482:Base Composition; D002843:Chromatin / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004270:DNA, Circular / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000032:analysis / Q000235:genetics; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism*; D011938:Rec A Recombinases / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D001426:Bacterial Proteins; D002843:Chromatin; D004270:DNA, Circular; D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D009692:Nucleic Acid Heteroduplexes; D009707:Nucleosomes; C040330:histone-like protein HU, bacteria; D011938:Rec A Recombinases; D004264:DNA Topoisomerases, Type I