Analysis of forward mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine in the bacteriophage P22 mnt repressor gene

Journal Article · Tue Apr 01 00:00:00 EST 1986 · J. Bacteriol.; (United States)

OSTI ID:5447271

Lucchesi, P; Carraway, M; Marinus, M G

We describe the isolation and genetic characterization of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced mutations in the phage P22 mnt repressor gene cloned in plasmid pBR322. Mutations in the mnt repressor gene or its operator on this plasmid, pPY98, confer a tetracycline resistance phenotype, whereas the wild-type plasmid confers tetracycline sensitivity. Cells carrying pPY98 were briefly exposed to MNNG to give 20 to 40% survival and a 50- to 100-fold increase in tetracycline-resistant cells. DNA sequence analysis showed that 29 to 30 MNNG-induced mutations were GC-to-AT transitions and one was an AT-to-GC transition. About 80% of the mutations are in three hotspots. This mutation spectrum is consistent with the proposed mechanism of mutagenic action of MNNG, which involves mispairing of an alkylated base, O/sup 6/-methylguanine. The mnt gene may be a useful target for determining mutagenic specificity at the nucleotide level because (i) forward mutations are easily isolated, (ii) the target size is small, and (iii) the DNA sequence changes of mutations can be determined rapidly.

• Research Organization: Univ. of Massachusetts Medical School, Worcester
• OSTI ID: 5447271
• Journal Information: J. Bacteriol.; (United States), Vol. 166:1
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIOPHAGES
MUTATIONS
NITROSO COMPOUNDS
GENETIC EFFECTS
CLONING
DNA SEQUENCING
GENES
PLASMIDS
TETRACYCLINES
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
BIOLOGICAL EFFECTS
CELL CONSTITUENTS
DRUGS
MICROORGANISMS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARASITES
STRUCTURAL CHEMICAL ANALYSIS
VIRUSES
560302* - Chemicals Metabolism & Toxicology- Microorganisms- (-1987)