Genetic analysis of the cIII gene of bacteriophage HK022

Kornitzer, Daniel; Altuvia, Shoshy; Oppenheim, Amos B.

doi:10.1128/jb.173.2.810-815.1991

Cited by 7 publications

(10 citation statements)

References 23 publications

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“…Mutants T58, A60, and A70 of the HK022 cIII gene were isolated as clones that grow normally even in the presence of IPTG. Protein labeling experiments demonstrated that these clones efficiently synthesize CIII protein (9). As shown in Table 1, the mutations also relieved the inhibition of growth of an infecting A cIII-phage.…”

Section: Resultsmentioning

confidence: 88%

“…Overexpression of the plasmid-encoded cIII gene induced by the addition of IPTG to the plate leads to a strong reduction in the growth rate of the host cell, yielding barely visible colonies (8,9). Mutants T58, A60, and A70 of the HK022 cIII gene were isolated as clones that grow normally even in the presence of IPTG.…”

Section: Resultsmentioning

confidence: 99%

“…Upon overexpression, both plasmid-encoded cIII genes strongly reduce the efficiency of plating of infecting clI-phages, probably because in the presence of an increased concentration of CIII the high levels of CII strongly enhance the Iysogenic response and inhibit the lytic pathway (8,9). In addition, both these cIII genes impair the growth of the host cell when overexpressed, and they induce the heat-shock response (refs.…”

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confidence: 99%

“…The sequences of the two CIII proteins, however, are rather different ( Extensive mutagenesis studies on the c1II gene of bacteriophage A, using several screening methods, yielded only low-translation or nonsense mutants (4,8). However, a similar study performed on the cIII gene of HK022 yielded, in addition to low-translation mutants, three mutants synthesizing nonfunctional CIII proteins (9).…”

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confidence: 99%

“…ptacAcIll (8) and ptacHKcIII (9), which carry the cIII gene of bacteriophages A and HK022, respectively, under the control of the tac promoter, were previously described. pCIII14-37: The polymerase chain reaction was used to introduce an EcoRI site before nucleotide 33354 and a HindIll site after nucleotide 33425 of the A sequence (14) and to amplify the intervening sequence (15).…”

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The activity of the CIII regulator of lambdoid bacteriophages resides within a 24-amino acid protein domain.

Kornitzer¹,

Altuvia²,

Oppenheim³

1991

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

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The CIII protein of lambdoid bacteriophages promotes lysogeny by stabilizing the phage-encoded CHI protein, a transcriptional activator of the repressor and integrase genes. We have isolated a set of missense mutations in the cll gene of phage A and of phage HK022 that yield inactive CIII proteins. All the mutations are located in the relatively conserved central region of the protein. A comparative analysis of the CIII protein sequence in A, HK022, and the lambdoid bacteriophage P22 leads us to suggest that this central region assumes an amphipathic at-helical structure. This part of the A cIII gene was cloned within a fragment of the lacZ gene (the a-complementing fragment). The resulting fusion protein displays CIII activity. Mutations that yield a nonfunctional fusion protein map within its CIII moiety. These results indicate that the central portion of the CIII protein is both necessary and sufficient for CIII activity.One way to regulate protein activity is through the control of its stability. This could be achieved by the control of the expression of specific proteases or through the synthesis of proteins that specifically inhibit these proteases. Little is known, however, about intracellular antiproteases (see refs. 1 and 2 for reviews).In the lysogenization process of the lambdoid bacteriophages, the CIII protein, a small, phage-encoded polypeptide, acts as a positive factor. Its presence in the cell results in the stabilization of the CII transcriptional activator (3, 4), a usually very unstable protein, with a half-life of the order of 1-2 min (5). The A CIII protein increases lysogeny in a wide range of lambdoid bacteriophages, each expressing a different CII protein (unpublished results). It has also been shown that overproduction of CIII induces the heat-shock response, probably through the stabilization of the heat-shock-specific subunit of the RNA polymerase, a,32 (6). The mechanism by which CIII achieves its effects, however, is as yet unknown.

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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The activity of the CIII regulator of lambdoid bacteriophages resides within a 24-amino acid protein domain.

Kornitzer¹,

Altuvia²,

Oppenheim³

1991

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

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Posttranscriptional Control of the Lysogenic Pathway in Bacteriophage Lambda

Oppenheim¹,

Kornitzer²,

Altuvia³

et al. 1993

Progress in Nucleic Acid Research and Molecular Biology

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Stochastic Kinetic Analysis of Developmental Pathway Bifurcation in Phage λ-Infected Escherichia coli Cells

1998

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Fluctuations in rates of gene expression can produce highly erratic time patterns of protein production in individual cells and wide diversity in instantaneous protein concentrations across cell populations. When two independently produced regulatory proteins acting at low cellular concentrations competitively control a switch point in a pathway, stochastic variations in their concentrations can produce probabilistic pathway selection, so that an initially homogeneous cell population partitions into distinct phenotypic subpopulations. Many pathogenic organisms, for example, use this mechanism to randomly switch surface features to evade host responses. This coupling between molecular-level fluctuations and macroscopic phenotype selection is analyzed using the phage λ lysis-lysogeny decision circuit as a model system. The fraction of infected cells selecting the lysogenic pathway at different phage:cell ratios, predicted using a molecular-level stochastic kinetic model of the genetic regulatory circuit, is consistent with experimental observations. The kinetic model of the decision circuit uses the stochastic formulation of chemical kinetics, stochastic mechanisms of gene expression, and a statistical-thermodynamic model of promoter regulation. Conventional deterministic kinetics cannot be used to predict statistics of regulatory systems that produce probabilistic outcomes. Rather, a stochastic kinetic analysis must be used to predict statistics of regulatory outcomes for such stochastically regulated systems.

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Genetic analysis of the cIII gene of bacteriophage HK022

Cited by 7 publications

References 23 publications

The activity of the CIII regulator of lambdoid bacteriophages resides within a 24-amino acid protein domain.

The activity of the CIII regulator of lambdoid bacteriophages resides within a 24-amino acid protein domain.

Posttranscriptional Control of the Lysogenic Pathway in Bacteriophage Lambda

Stochastic Kinetic Analysis of Developmental Pathway Bifurcation in Phage λ-Infected Escherichia coli Cells

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