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. 1991 Oct;173(20):6406–6410. doi: 10.1128/jb.173.20.6406-6410.1991

LexA protein of Escherichia coli represses expression of the Tn5 transposase gene.

C T Kuan 1, I Tessman 1
PMCID: PMC208973  PMID: 1655708

Abstract

The LexA protein of Escherichia coli represses expression of a variety of genes that, by definition, constitute the SOS regulon. Genetic evidence suggests that Tn5 transposition is also regulated by the product of the lexA gene (C.-T. Kuan, S.-K. Liu, and I. Tessman, Genetics 128:45-57, 1991). We now show that the LexA protein represses expression of the tnp gene, located in the IS50R component of Tn5, which encodes a transposase, and that LexA does not repress expression of the IS50R inh gene, which encodes an inhibitor of transposition. Elimination of LexA resulted in increased expression of the tnp gene by a factor of 2.7 +/- 0.4, as indicated by the activity of a lacZ gene fused to the tnp gene. LexA protein retarded the electrophoretic movement of a 101-bp segment of IS50R DNA that contained a putative LexA protein-binding site in the tnp promoter; the interaction between the LexA repressor and the promoter region of the tnp gene appears to be relatively weak. These features show that the IS50R tnp gene is a member of the SOS regulon.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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