Frameshift mutations induced by four isomeric nitroacridines and their des-nitro counterpart in the lacZ reversion assay in Escherichia coli.
Acridines are well-known as compounds that intercalate noncovalently between DNA base pairs and induce +/-1 frameshift mutations at sites of monotonous repeats of a single base. Reactive derivatives of acridines, including acridine mustards and nitroacridines, form covalent adducts in DNA and exhibit mutagenic properties different from the simple intercalators. We compared the frameshift mutagenicity of the cancer chemotherapy drug nitracrine (1-nitro-9-(3'-dimethylaminopropylamino)-acridine), its des-nitro counterpart 9-(3'-dimethylaminopropylamino)-acridine (DAPA), and its 2-, 3-, and 4-nitro isomers (2-, 3-, and 4-nitro-DAPA) in the lacZ reversion assay in Escherichia coli. DAPA is a simple intercalator, much like the widely studied 9-aminoacridine. It most strongly induced +/-1 frameshift mutations in runs of guanine residues and more weakly induced -1 frameshifts in a run of adenine residues. A nitro group in the 1, 3, or 4 position of DAPA reduced the yield of +/-1 frameshift mutations. DAPA weakly induced -2 frameshifts in an alternating CG sequence. In contrast, nitracrine and its 3-nitro isomer resembled the 3-nitroacridine Entozon in effectively inducing -2 frameshift mutations. The 2- and 4-nitro isomers were less effective than the 1- and 3-nitro compounds in -2 frameshift mutagenesis. The results are interpreted with respect to intercalation, steric interactions, effects of base strength on DNA binding, enzymatic processing, and a slipped mispairing model of frameshift mutagenesis.
Hoffmann
George R
GR
Department of Biology, College of the Holy Cross, Worcester, Massachusetts 01610-2395, USA. ghoffmann@holycross.edu
Yin
Catherine C
CC
Terry
Caitlin E
CE
Ferguson
Lynnette R
LR
Denny
William A
WA
D000166:Acridines / Q000737:chemistry / Q000145:classification* / Q000633:toxicity*; D000970:Antineoplastic Agents / Q000737:chemistry / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D016368:Frameshift Mutation; D007763:Lac Operon; D015394:Molecular Structure; D009152:Mutagenicity Tests; D009564:Nitracrine / Q000031:analogs & derivatives / Q000737:chemistry / Q000633:toxicity
D000166:Acridines; D000970:Antineoplastic Agents; C001815:C 684; D009564:Nitracrine