LexA protein inhibits transcription of the E. coli uvrA gene in vitro

Treatment of Escherichia coli with radiation or chemical carcinogens induces a number of cellular functions to counteract the damage inflicted by such treatments (see ref. 1 for a review). One of these inducible functions is the SOS response, which is controlled by the recA and lexA genes: single-stranded DNA produced as a result of DNA damage binds to recA protein (RecA), activating its protease function; activated RecA cuts lexA protein (LexA), the represser of the SOS genes, thereby inactivating it and turning on these genes2–4. The SOS genes include recA and lexA themselves, and recent work has shown that the two genes have similar operators where LexA binds in vitro, inhibiting their transcription3,4. It is anticipated that other genes under the control of recA and lexA will have similar operators. Recent genetic5,6 and biochemical7 data suggest that the excision repair genes uvrA and uvrB are part of the recA–lexA regulon and are at least partly responsible for recA–lexA-mediated inducible DNA repair. In support of these results we have reported that uvrB has a promoter that is repressed by LexA in vitro8. We now show that uvrA has an operator similar to those of other SOS genes and that LexA binds to this operator and inhibits the transcription of the uvrA gene in vitro.

[1]  A. Sancar,et al.  A general approach for purifying proteins encoded by cloned genes without using a functional assay: isolation of the uvrA gene product from radiolabeled maxicells. , 1981, Nucleic acids research.

[2]  D. Galas,et al.  DNAse footprinting: a simple method for the detection of protein-DNA binding specificity. , 1978, Nucleic acids research.

[3]  D. Mount,et al.  Cleavage of the Escherichia coli lexA protein by the recA protease. , 1980, Proceedings of the National Academy of Sciences of the United States of America.

[4]  Aziz Sancar,et al.  The uvrB gene of Escherichia coli has both lexA-repressed and lexA-independent promoters , 1982, Cell.

[5]  J. W. Chase,et al.  Sequences of the ssb gene and protein. , 1981, Proceedings of the National Academy of Sciences of the United States of America.

[6]  P Howard-Flanders.  Inducible repair of DNA. , 1981, Scientific American.

[7]  N. D. Clarke,et al.  Identification of the uvrA gene product. , 1981, Journal of molecular biology.

[8]  C. Kenyon,et al.  Expression of the E. coli uvrA gene is inducible , 1981, Nature.

[9]  M Ptashne,et al.  Mechanism of action of the lexA gene product. , 1981, Proceedings of the National Academy of Sciences of the United States of America.

[10]  H. Kagamiyama,et al.  The nucleotide sequence surrounding the promoter region of colicin E1 gene. , 1981, Gene.

[11]  H. Echols,et al.  SOS induction and autoregulation of the himA gene for site-specific recombination in Escherichia coli. , 1981, Proceedings of the National Academy of Sciences of the United States of America.

[12]  W. Gilbert,et al.  Sequencing end-labeled DNA with base-specific chemical cleavages. , 1980, Methods in enzymology.

[13]  J W Little,et al.  Purified lexA protein is a repressor of the recA and lexA genes. , 1981, Proceedings of the National Academy of Sciences of the United States of America.

[14]  M. Fogliano,et al.  Evidence for the inducibility of the uvrB operon , 1981, Nature.