title: Role of ATP in removal of psoralen cross-links from DNA of Escherichia coli permeabilized by treatment with toluene.
abstract: Removal of interstrand cross-linked from DNA was examined in Escherichia coli permeabilized by treatment with toluene. Under these conditions, the reaction requires ATP and Mg2+, and the mechanism appears to be similar to that occurring in whole cells. Under optimum conditions, the rate constant was 0.06 min-1. Genetical, physical, and biochemical analysis of the repair process suggest the following mechanism. In an ATP-dependent reaction, the uvrA and uvrB gene products cleave a phosphodiester bond on the 5' side of one arm of the cross-link, producing a 3'-OH terminus. Subsequently, DNA polymerase I (5'-3' exonuclease activity) makes a second strand cut on the 3' side of the cross-link in the same DNA strand, completing removal of the covalent link between complementary strands. The second reaction did not occur in a uvrD- strain, which had normal levels of DNA polymerizing activity. The uvrD gene may regulate the specificity or activity of the 5'-3' exonuclease of DNA polymerase I in vivo.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D003374:Coumarins / Q000494:pharmacology*; D004256:DNA Polymerase I / Q000378:metabolism; D004260:DNA Repair; D004269:DNA, Bacterial / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D005363:Ficusin / Q000494:pharmacology*; D009695:Nucleic Acid Renaturation; D014050:Toluene / Q000494:pharmacology*; D014461:Ultracentrifugation
chemical_list: D003374:Coumarins; D004269:DNA, Bacterial; D014050:Toluene; D000255:Adenosine Triphosphate; D004256:DNA Polymerase I; D005363:Ficusin