Active and Inactive States of the CI Gene in Some   Defective Phages

Calef, E.; Neubauer, Zdeněk

doi:10.1101/sqb.1968.033.01.087

Cited by 34 publications

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“…However, Enrico Calef and Zdenek Neubauer, also in 1968, working under similarly dismal conditions in Naples, concluded that a trans-acting negative regulator of cI expression must exist (25). Like the Paris group, they isolated and characterized survivors of cIts lysogens, and again, as in the work of Eisen et al (52), two classes were obtained.…”

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confidence: 79%

Little Lambda, Who Made Thee?

Gottesman

Weisberg

2004

Microbiol Mol Biol Rev

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SUMMARY The study of the bacteriophage λ has been critical to the discipline of molecular biology. It was the source of key discoveries in the mechanisms of, among other processes, gene regulation, recombination, and transcription initiation and termination. We trace here the events surrounding these findings and draw on the recollections of the participants. We show how a particular atmosphere of interactions among creative scientists yielded spectacular insights into how living things work.

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confidence: 79%

Little Lambda, Who Made Thee?

Gottesman

Weisberg

2004

Microbiol Mol Biol Rev

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“…The Qegulatory Qegion of X X transcription .4 prm product prevents repressor synthesis in nonimmune lysogens (5,6). Other evidence has suggested that cii, cIII, and cYgenes needed for efficient establishment of lysogeny-may also participate in repressor regulation (6)(7)(8).…”

mentioning

confidence: 99%

Control of λ Repressor Synthesis

Reichardt

Kaiser

1971

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

190

114

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The X repressor is the only phage protein needed to maintain immunity (1). By binding two operators, Or and 01 in Fig. 1, this protein directly prevents the transcription of the two early phage operons (2, 3). Consequently, only one operon, that which includes cI the structural gene for repressor (2), is transcribed in the presence of active repressor.Since Eisen et al. (4) (23,24). cro reduces N expression (25) and ci expression.Mutations used in this paper include: V3, vl, and vS3u, which map in Or (2, 11); sex, possibly in Pl, which reduces leftward transcription of N and cIII (26), and X3-and x13-, possibly in Pr, which abolish rightward transcription of cro, cdI, and 0 (27). The DNA deleted in two prophage strains is denoted below the genetic map. 2185

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“…In these derepressed lysogens the ere gene is expressed but lyric development is blocked through a mutation in the N gene and the genes responsible for DNA replication. These imm-lysogens channel the superinfecting ~ phage toward the lyric cycle (Calef and Neubauer, 1968). Experimental data suggest that ere depresses expression of the N-cIII-exo operon and the cII-O-P operon and thereby interferes indirectly with ~ represser synthesis (Echols et al, 1973 ;Galland et al, 1973).…”

Section: Suppression Ol Cy Mutants By the Sar Mutationmentioning

confidence: 99%

A pleiotropic regulatory mutation in λ bacteriophage

Honigman

Oppenheim

et al. 1975

Molec. Gen. Genet.

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Lambda bacteriophage mutants, lambdasar, were isolated. These mutants can form plaques on a non lysogenic lawn and are unable to grow on nonimmune (imm-), cro constitutive hosts. Analysis of the restriction of lambdasar by a set of defective lysogens suggested that both the cro and cII gene products participate in the inhibition. The sar mutations were mapped in the ori region between the genes cII and O. Complementation experiments showed that under the restrictive conditions lamdasar is defective in the expression of both the N and the O genes. Transcription analyses support these findings, as lambdasar is unable to serve as a template for transcription after infecting cro constitutive hosts. In addition lambdasar does not replicate under the restrictive conditions, although its DNA can bind to the host membrane to some extent. The Sar phenotype can be relieved by removing sites of action of cro either by a V2 mutation or by substituting the lambda immunity region by imm434 or imm21. Similarly introducing a cy mutation, which interferes with the action of the cII gene product, also eliminates the Sar effect. The sar mutation can suppress cy mutations as manifested in plaque morphology, lysogenization frequency, cI repressor synthesis and the expression of rex function. Suppression takes place only when the sar mutation is present in cis to cy and it requires the action of the cII and cIII gene products. It is suggested that the sar mutation suppresses cy by activating a new promoter for repressor synthesis, pro. The results also suggest that the cII and cIII gene products may act at a site other than y.

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Active and Inactive States of the CI Gene in Some Defective Phages

Cited by 34 publications

References 0 publications

Little Lambda, Who Made Thee?

Little Lambda, Who Made Thee?

Control of λ Repressor Synthesis

A pleiotropic regulatory mutation in λ bacteriophage

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