Induction of λCI prophages inEscherichia coli C600 T44

Klaus, S.; Noack, D.; Hüller, E.

doi:10.1002/jobm.3630120507

Cited by 7 publications

(2 citation statements)

References 23 publications

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“…The UV-sensitive complexes exhibit shorter latent periods than the wild-type lysogen but all latent periods decrease with UV dose. From this it can be concluded that the time needed for repressor inactivation falls with increasing UV dose, because the duration of vegetative phage • lysogenic complex with wild type; 9 9 lysogenic complex with the phage mutant ~.ind s development does not depend on the UV dose (KLaus et al, [8]). This result corresponds with curve 3 in Fig.…”

Section: Resultsmentioning

confidence: 96%

“…All lambda prophages inducible by UV irradiation are induced in the mutant host strain E. coli C600 T44 (GoLDTHWAIT and JACOB, [4]; KIRBX" et al, [5]) after heatiug from 30 ~ to 42 ~ Separate experiments (KLAuS et al [8]) suggest that in this strain the feedback loop for eudproduct inhibition is temperature sensitive. The strain was lysogenized with several lamdba phage mutants the repressors of which show different affinities to the inactivating molecules that aceumulate after heating the respective lysogenic complexes.…”

Section: Resultsmentioning

confidence: 98%

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A model for the regulation of replication of bacterial and episomal DNA

Noack¹,

Klaus²

1973

Acta Physica

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A mathematical model is proposed for the relationship between the bacterial cell processes resulting in the initiation of DNA replication that are responsible for DNA and protein synthesis. It is assumed that one or several precursors of DNA synthesis actas a trigger for the replication system of both the bacterial and episomal DNA preseut. By mathematical analysis it is shown that this model yields a stable cell cycle with a regulated cell volume at the time of intiation of DNA replication. Some proposals resulting from the model ate experimentally proved with E. coli strains lysogenic for the ). bacteriophage, the DNA of which is an example of episomal DNA. The initiation timing of phage DNA replication is in accordance with the model, in that the mode and duration of inhibition of bacterial DNA replication causes the accumulation of DNA precursors leading to the initiation of replication of bacterial and episomal DNA.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 98%

A model for the regulation of replication of bacterial and episomal DNA

Noack¹,

Klaus²

1973

Acta Physica

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Einfluß von Purin‐ und Pyrimidinderivaten auf die Prophageninduktion in Escherichia coli C600 T44

Noack

Klaus

1972

J of Basic Microbiology

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The inducibility of the prophages I+ and A inan within the lysogenic, temperature sensitive strain E. coli C600 T44 can be influenced by precursors of nucleic acid metabolism or by substances chemically related to those. With an agar diffusion test 63 substances of this kind were tested both qualitatively and quantitatively. It was shown that there are substances with stimulating or inhibiting action, respectively, on the inducibility of prophages.Furthermore, the prophages I+ and 1 i d * exhibit different reactions on the exposure of the respective lysogenic strains against some substances tested. A small selection of effective substances are moreover qualitatively tested on the nonlysogenic strain E . coli C600 T44 and on the lysogenic complex E. coli C600 T44 (I ind-) the prophage of which is known to be not inducible by UV light. The results are discussed in terms of a different sensitivity of the lambda phage repressors against intermediates of the nucleic acid metabolism. An immediate comparison between the action of test substances and control substances such as adenine, guanosine, chloramphenicol, and nalidixic acid is possible on each test plate.Die Untersuchung von Regelprozessen, die zur Aufrechterhaltung der Lysogenie oder zur Einleitung der Induktion notwendig sind, stellt einen sehr effektiven Zugang zur Aufkliirung von Regulationsprinzipien in biologischen Systemen dar. Besonders bevorzugt liierbei ist das lysogene System E . 1. Durch eine direkte thermische Inaktivierung der Repressormolekiile, wenn diese infolge einer Mutation im CI-Gen temperatursensibel sind und bei Erwarmung der lysogenen Bakterienkultur von 30 "C auf 40 "C einen Kon-

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A model on the induction by UV irradiation of Escherichia coli bacteria lysogenic with the bacteriophage Lambda

Noack

Rontó

1974

J of Basic Microbiology

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The induction of Lambda prophages in lysogenic Escherichia coli cells is started after inactivation of repressor molecules coded for by the prophage genome itself. All agents known to inhibit bacterial DNA synthesis are able to initiate a set of processes resulting in the inactivation of these repressors. I n the case of UV light as an inducing agent i t is suggested that the UV mediated damages within the bacterial DNA diminish the replication velocity leading through a set of intermediate processes t o the inactivation of phage repressors by accumulation of repressor inactivating precursors of DNA synthesis. The analytical function for the dose effect curve is obtained from the product of the probability PI of cells containing I UV damages multiplied by the number 1 of UV damages after summing up all possible numbers of E. The probability of P i is calculated on the basis of the radiation kinetic model of R O N T~ et al. (1972). The theoretical dose effect curve, obtained shows a shoulder with an extrapolation number of 1.2 and a linear part a t high irradiation doses in semilogarithmic plot. The experimental data obtained with UV induction of E . coli K12 (A) are consistent with the model and show that only a few UV damages smaller than 10 per bacterial chromosome are sufficient for induction.The lysogenic complex E . coli-phage Lambda contains the genome of the bacteriophage linearely integrated within the bacterial chromosome as a socalled prophage. The genetic information of this prophage is repressed by the action of repressor molecules coded for by the CI gene of the prophage. This CI gene is the only one which is not under negative control of repressors. All agents known to inhibit DNA synthesis such as mitomycine C treatment or thymine starvation or UV irradiation lead to the induction of vegetative phage development by lifting the repression capacity of the phage repressors. Thereafter, the prophage is excised and autonomously replicated. The biological detectable effect is the lysis of cells or the formation of infective phage particles or the loss of colony forming ability (for review see HERSHEY 1971). By several authors (GOLDTHWAIT and JACOB 1964, RUFX et al. 1971 it has been shown that after the stop of DNA synthesis some DNA precursors are accumulated resulting directly or indirectly in the inactivation of phage repressor molecules. In the case of UV irradiation used as inducing agent it should be proved whether the radiation kinetic model presented by R O N T~ et al. (1967) and developed to the special problem of UV mediated inactivation of phage repressors, is consistent with experimental data obtained from E. coli lysogenic with phage Lambda.

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Induction of λCI prophages inEscherichia coli C600 T44

Cited by 7 publications

References 23 publications

A model for the regulation of replication of bacterial and episomal DNA

A model for the regulation of replication of bacterial and episomal DNA

Einfluß von Purin‐ und Pyrimidinderivaten auf die Prophageninduktion in Escherichia coli C600 T44

A model on the induction by UV irradiation of Escherichia coli bacteria lysogenic with the bacteriophage Lambda

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