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DNA-Damaging Agents Stimulate Gene Expression at Specific Loci in Escherichia coli
Cynthia J. Kenyon and Graham C. Walker
Proceedings of the National Academy of Sciences of the United States of America
Vol. 77, No. 5, [Part 2: Biological Sciences] (May, 1980), pp. 2819-2823
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/8786
Page Count: 5
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Operon fusions in Escherichia coli were obtained that showed increased β -galactosidase expression in response to treatment with the DNA-damaging agent mitomycin C. These fusions were generated by using the Mud(ApR, lac) vector [Casadaban, M. J. & Cohen, S. N. (1979) Proc. Natl. Acad. Sci. USA 76, 4530-4533] to insert the lactose structural genes randomly into the bacterial chromosome. Induction of β -galactosidase in these strains, which carried fusions of lac to these din (damage-inducible) loci, was (i) triggered by UV light as well as by mitomycin C and (ii) abolished by either a recA- or a lexA- mutation. Similar characteristics of induction were observed when the lactose genes were fused to a prophage λ promoter by using Mud(Mud(ApR, lac). These results indicate that E. coli contains a set of genes that, like prophage λ genes, are expressed in response to DNA-damaging agents and regulated by the recA and lexA gene products. These din genes map at five bacterial loci. One din::Mud(ApR, lac) insertion results in a UV-sensitive phenotype and may be within the uvrA transcriptional unit.
Proceedings of the National Academy of Sciences of the United States of America © 1980 National Academy of Sciences