Isolation and Characterization of Escherichia coli Mutants With Altered Rates of Deletion Formation

Using site-specific mutagenesis in vitro we constructed a genetic system to detect mutants with altered rates of deletion formation between short repeated sequences in Escherichia coli. After in vivo mutagenesis with chemical mutagens and transposons, the system allowed the identification of mutants...

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Bibliographic Details
Published in:Genetics (Austin) 1991-01, Vol.127 (1), p.21-30
Main Authors: Whoriskey, S. K, Schofield, M. A, Miller, J. H
Format: Article
Language:English
Subjects:
Bacteriology
Base Sequence
Biological and medical sciences
Blotting, Southern
Chromosome Deletion
Chromosome Mapping
Chromosomes, Bacterial
Cloning, Molecular
DNA, Bacterial
Escherichia coli - genetics
Escherichia coli - isolation & purification
Fundamental and applied biological sciences. Psychology
Genes, Bacterial
Genetics
Investigations
Lac Operon
Microbiology
Molecular Sequence Data
Mutagenesis, Site-Directed
Mutation - genetics
Phenotype
Species Specificity
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Summary:Using site-specific mutagenesis in vitro we constructed a genetic system to detect mutants with altered rates of deletion formation between short repeated sequences in Escherichia coli. After in vivo mutagenesis with chemical mutagens and transposons, the system allowed the identification of mutants with either increased or decreased deletion frequencies. One mutational locus, termed mutR, that results in an increase in deletion formation, was studied in detail. The mutR gene maps at 38.5 min on the E. coli genetic map. Since the precise excision of many transposable elements is also mediated at short repeated sequences, we investigated the effects of the mutant alleles, as well as recA, on precise excision of the transposon Tn9. Neither mutR nor recA affect precise excision of the transposon Tn9, from three different insertions in lacI, whereas these alleles do affect other spontaneous deletions in the same system. These results indicate that deletion events leading to precise excision occur principally via a different pathway than other random spontaneous deletions. It is suggested that, whereas precise excision occurs predominantly via a pathway involving replication enzymes (for instance template strand slippage), deletions on an F'factor are stimulated by recombination enzymes.
ISSN:0016-6731
1943-2631
1943-2631
DOI:10.1093/genetics/127.1.21