E. coli recA protein-directed cleavage of phage λ repressor requires polynucleotide

Craig, Nancy L.; Roberts, Jeffrey W.

doi:10.1038/283026a0

Cited by 349 publications

(167 citation statements)

References 24 publications

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“…RecA is then responsible for directing phage derepression via rapid autocleavage of the lambdoid repressor protein CI (Craig & Roberts, 1980). Under inducing conditions (1 mg norfloxacin ml 21 ), there was the expected large increase in the levels of luminescence produced by both the single and double lysogens (Fig.…”

Section: P C M Fogg and Othersmentioning

confidence: 99%

Cumulative effect of prophage burden on Shiga toxin production in Escherichia coli

et al. 2012

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Section: P C M Fogg and Othersmentioning

confidence: 99%

Cumulative effect of prophage burden on Shiga toxin production in Escherichia coli

et al. 2012

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“…The presence of recAo281 allows us to confirm that the sole effect of UV irradiation in the induction of A prophage and reactivation of UV-irradiated phage is not the induction of recA (4)(5)(6)(7)(8)(9)(10). If it were, we would expect inability to be lysogenized by CI+ A and high constitutive reactivation of UV-irradiated phage to be the phenotype of a recAo281 strain.…”

Section: Methodsmentioning

confidence: 85%

“…These results suggest that they may be regulatory mutations in either the operator or promoter of the recA gene (4). An alternative explanation is suggested by current models of regulation of recA protein synthesis (5)(6)(7)(8)(9), according to which induction of synthesis occurs when the expression of proteolytic activity of recA protein results in cleavage of the lexA-encoded repressor of the recA gene. Recently, this cleavage reaction has been verified (10).…”

mentioning

confidence: 86%

“…If it were, we would expect inability to be lysogenized by CI+ A and high constitutive reactivation of UV-irradiated phage to be the phenotype of a recAo281 strain. UV irradiation may provide at least two possible additional requirements for SOS induction: provision of one or more cofactors to activate recA protein (9) and induction of genes other than recA (23). The mutation recA441 obviates the need for UV irradiation to accomplish the first, possibly because the mutant protein more effectively competes with other proteins for low levels of cofactors (e.g., single-stranded DNA) present in unirradiated cells.…”

Section: Methodsmentioning

confidence: 99%

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Evidence that rnmB is the operator of the Escherichia coli recA gene.

Volkert¹,

Margossian²,

Clark³

1981

Proc. Natl. Acad. Sci. U.S.A.

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rnmB281 leads to high constitutive levels of recA protein such that no increase after UV-inducing treatment occurs. The mutation maps in or near the portion of recA corresponding to the NH2-terminal end of the protein. rnmB mutations were originally detected as one class of suppressors of UV sensitivity in a lexAl02 uvrAl55 mutant strain of E. coli B/r (3, 4). Their action is to suppress lexA-mediated UV sensitivity; when an rnmB mutation is introduced, UV sensitivity of uvrAl55 single mutants is not suppressed (4), whereas lexA single mutants become more UV resistant (unpublished data). rnmB mutations are tightly linked to recA and result in constitutive synthesis of large amounts of recA protein (4). These results suggest that they may be regulatory mutations in either the operator or promoter of the recA gene (4). An alternative explanation is suggested by current models of regulation of recA protein synthesis (5-9), according to which induction of synthesis occurs when the expression of proteolytic activity of recA protein results in cleavage of the lexA-encoded repressor of the recA gene. Recently, this cleavage reaction has been verified (10). Thus rnmB mutations could be recA mutations that cause the proteolytic activity of the recA protein to be constitutive and thus could result in continuous cleavage of lexA repressor molecules. These two explanations can easily be distinguished. Mutations in recA that alter protease activity should be either dominant to recA+ and act in trans to cause constitutive recA protein synthesis or recessive to recA+. On the other hand, operator-constitutive or up-promoter mutations should be codominant with their wild-type alleles and should act only in cis.The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.To test these possibilities experimentally, merodiploids heterozygous for both rnmB and recA alleles were constructed. We chose the mutant recA alleles, cis to rnmB+, whose recA proteins could be separated by two-dimensional polyacrylamide gel electrophoresis from the wild-type protein, determined by recA', cis to rnmB281. Thus, we can distinguish cis and trans regulatory effects.Establishment of the genetic nature of the rnmB281 mutation is necessary for understanding its effects on the expression of SOS functions. MATERIALS AND METHODSBacterial Strains. The bacterial strains used are listed in Table 1. rnmB281 can be cotransduced with srl-300::TnlO, whose inheritance can be detected by tetracycline resistance (TetR) (11). Inheritance of rnmB281 can be determined by P1 transductional backcrossing into MV1131, a tetracycline sensitive (TetS) lexA102 uvrAl55 mutant strain and testing TetR transductants for suppression of UV sensitivity. Donors that gave UV-resistant (UVR) transductants of MV1131 were presumed to carry the rnmB281 mutations. These donors were examined for constitutive expression of recA prote...

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“…Without the repressor, the rest of the viral genes are switched on again. This triggers the transformation from a quiet hitchhiker in the bacterial genome to an active virus bent on replicating itself and destroying the bacterial cell (1).…”

Section: Cutting and Pastingmentioning

confidence: 99%

Profile of Nancy L. Craig

Trivedi¹

2012

Proc. Natl. Acad. Sci. U.S.A.

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E. coli recA protein-directed cleavage of phage λ repressor requires polynucleotide

Cited by 349 publications

References 24 publications

Cumulative effect of prophage burden on Shiga toxin production in Escherichia coli

Cumulative effect of prophage burden on Shiga toxin production in Escherichia coli

Evidence that rnmB is the operator of the Escherichia coli recA gene.

Profile of Nancy L. Craig

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