Frameshift mutations induced by four isomeric nitroacridines and their des-nitro counterpart in thelacZ reversion assay inEscherichia coli

Abstract

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.

Potentiation of the mutagenicity and recombinagenicity of bleomycin in yeast by unconventional intercalating agents

“…The reported genotoxic responses to these compounds in other assays do not include potent frameshift mutagenesis in bacteria, as occurs with simple intercalators with three fused rings. Such frameshift mutagenesis seems to depend on the enhanced formation or stabilization of mispaired intermediates [Ferguson and Denny, 1990;Hoffmann et al, 2003Hoffmann et al, , 2006Hoffmann and Fuchs, 1997] that facilitate slipped mispairing [Streisinger et al, 1966]. All intercalators are apparently not equivalent in this respect.…”

Where do dyes go inside living cells? Predicting uptake, intracellular localisation, and accumulation using QSAR models

“…Mutagenisis following binding of cationic dyes to DNA [57] [ 64,65]. However, in vivo, both types of nucleic acid are closely associated with various proteins and with the dsDNA of the interphase chromosomes being condensed, owing to its being wound around the nuclear histones to form nucleosomes.…”