A New Class of Escherichia coli recBC Mutants: Implications for the Role of RecBC Enzyme in Homologous Recombination

Mutants of Escherichia coli sensitive to phage T4 gene 2 mutants were obtained following ethyl methanesulfonate mutagenesis. By mapping and complementation analysis, the mutations in each of the six mutants are in recB and recC. By both in vivo and in vitro analyses, the nuclease activity of RecBC e...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1984-12, Vol.81 (24), p.7850-7854
Main Authors: Chaudhury, Abdul M., Smith, Gerald R.
Format: Article
Language:English
Subjects:
Alleles
Bacteria
Bacteriophage T4
Bacteriophages
Crosses, Genetic
DNA
DNA damage
Enzymes
Escherichia coli
Escherichia coli - enzymology
Escherichia coli - genetics
Escherichia coli Proteins
Exodeoxyribonuclease V
Exodeoxyribonucleases - genetics
Genes
Genes, Bacterial
Genes, Dominant
Genes, Viral
Genetic Complementation Test
Genetic mutation
Genotype
Mutation
Phenotypes
T-Phages - genetics
Transduction, Genetic
Viability
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Summary:Mutants of Escherichia coli sensitive to phage T4 gene 2 mutants were obtained following ethyl methanesulfonate mutagenesis. By mapping and complementation analysis, the mutations in each of the six mutants are in recB and recC. By both in vivo and in vitro analyses, the nuclease activity of RecBC enzyme is undetectable in these mutants. However by several other criteria, such as proficiency in recombination, relative resistance to UV radiation, and viability of the cells in the culture, these mutants are almost identical to their recBC+parent. The properties of these mutants indicate that the ATP-dependent double-stranded DNA exonuclease activity of RecBC enzyme is not required for recombination. Chi recombinational hotspots, which stimulate recombination by the RecBC pathway, have no detectable activity in the mutants. This result suggests that the nuclease activity of RecBC enzyme is required for Chi activity and is consistent with the hypothesis that Chi stimulates recombination by directing RecBC enzyme to cut DNA at or near Chi.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.81.24.7850