Analysis of forward mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine in the bacteriophage P22 mnt repressor gene
UMass Chan Affiliations
Department of Biochemistry and Molecular PharmacologyDocument Type
Journal ArticlePublication Date
1986-04-01Keywords
Base SequenceDNA, Viral
*Genes, Viral
Methylnitronitrosoguanidine
*Mutation
Plasmids
Repressor Proteins
Salmonella Phages
Transcription Factors
Bacteria
Biochemistry, Biophysics, and Structural Biology
Genetic Phenomena
Pharmacology, Toxicology and Environmental Health
Metadata
Show full item recordAbstract
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 of 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, O6-methylguanine. The mnt gene may be a useful target for determining mutagenic specificity at the nucleotide level because forward mutations are easily isolated, the target size is small, and the DNA sequence changes of mutations can be determined rapidly.Source
J Bacteriol. 1986 Apr;166(1):34-7.
DOI
10.1128/jb.166.1.34-37.1986Permanent Link to this Item
http://hdl.handle.net/20.500.14038/26085PubMed ID
3957871Related Resources
ae974a485f413a2113503eed53cd6c53
10.1128/jb.166.1.34-37.1986