title: Enhancement of binding rate of RecA protein to DNA by carcinogenic benzo[a]pyrene derivatives and selective change of adduct conformation.
abstract: The association kinetics of RecA protein from Escherichia coli to DNA is strongly enhanced if even a minor fraction of DNA bases has been modified by a carcinogenic (+)-anti metabolite of benzo[a]pyrene (BPDE). The enhancement is much smaller with the less carcinogenic (-)-anti enantiomer of BPDE suggesting the possibility that the RecA protein binds selectively to the proto-oncogenic target. Most importantly, the binding of RecA to DNA modified with the latter enantiomer is found to give rise to a reorganization of this BPDE adduct from an intercalation site into a minor groove site. This indicates that the binding mechanism of RecA is via intercalation of some amino acid moiety, a discovery that could explain the approximately 50% contour length increase of the DNA within its fibrous complex with RecA.
authors.affiliation: Department of Physical Chemistry, Chalmers University of Technology, Gothenburg, Sweden.
authors.forename: S K
authors.initials: SK
authors.lastname: Kim
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: B
authors.initials: B
authors.lastname: Jernström
authors.forename: B
authors.initials: B
authors.lastname: Nordén
mesh_terms: D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide / Q000378:metabolism / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism*; D018736:DNA Adducts; D007700:Kinetics; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011938:Rec A Recombinases / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D018736:DNA Adducts; C043931:benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-DNA; D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D004247:DNA; D011938:Rec A Recombinases