title: Repair of 8-methoxypsoralen induced DNA interstrand cross-links in Tetrahymena thermophila. The effect of inhibitors of macromolecular synthesis.
abstract: The effect of several growth-inhibiting compounds on the repair of 8-methoxypsoralen-UVA-light-induced DNA interstrand cross-links has been studied in the protozoan Tetrahymena thermophila. The repair process was analyzed by the alkaline elution technique and could be divided into 3 phases: a protein-DNA complexing phase, a DNA-incision phase and finally a DNA-ligation phase. The incision was found to be completely inhibited by novobiocin (50 micrograms/ml), nalidixic acid (150 micrograms/ml), n-butyrate (15 mM) and cycloheximide (1 microgram/ml), while no effect was observed for cytosine-1-beta-D-arabinofuranoside (10 mM), puromycin (1 mM), hydroxyurea (5 mM) or 3-aminobenzamide (2.5 mM). None of the compounds showed any effect on the protein-DNA complexing step, and the ligation was partly inhibited only by nalidixic acid (150 micrograms/ml). The involvement of topoisomerases in the repair of psoralen-induced DNA interstrand cross-links is suggested.
mesh_terms: D004260:DNA Repair / Q000187:drug effects*; D006131:Growth Inhibitors / Q000494:pharmacology*; D008730:Methoxsalen / Q000378:metabolism / Q000494:pharmacology*; D013768:Tetrahymena / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism
chemical_list: D006131:Growth Inhibitors; D008730:Methoxsalen