Showing papers on "Lambda phage published in 1972"
TL;DR: Most mutations rendering E. coli K12 resistant to phage lambda, map in two genetic regions malA and malB, where lamB is specifically involved in the lambda receptor synthesis and malT is believed to be a positive regulatory gene necessary for the induction of the "maltose operons" in the malA region.
Abstract: Most mutations rendering E. coli K12 resistant to phage lambda, map in two genetic regions malA and malB.-The malB region contains a gene lamB specifically involved in the lambda receptor synthesis. Twenty-one independent lamB mutations studied by complementation belonged to a single cistron. This makes it very likely that lamB is monocistronic. Among the lamB mutants some are still sensitive to a host range mutant of phage lambda. Mutations mapping in a proximal gene essential for maltose metabolism inactivate gene lamB by polarity confirming that both genes are part of the same operon. Because cases of intracistronic complementation have been found, the active lamB product may be an oligomeric protein.-Previously all lambda resistant mutations in the malA region have been shown to map in the malT cistron. malT is believed to be a positive regulatory gene necessary for the induction of the "maltose operons" in the malA region and in the malB region of the E. coli K12 genetic map. No trans dominant malT mutation have been found. Therefore if they exist, they occur at a frequency of less than 10(-8), or strongly reduce the growth rate of the mutants.
100 citations
TL;DR: Plaque-forming, galactose-transducing lambda strains have been isolated from lysogens in which bacterial genes have been removed from between the galactOSE operon and the prophage by deletion mutation.
Abstract: Plaque-forming, galactose-transducing lambda strains have been isolated from lysogens in which bacterial genes have been removed from between the galactose operon and the prophage by deletion mutation.—A second class has been isolated starting with a lysogenic strain which carries a deletion of the genes to the right of the galactose operon and part of the prophage. This strain was lysogenized with a second lambda phage to yield a lysogen from which galactose-transducing, plaque-forming phages were obtained. These plaque-forming phages were found to be genetically unstable, due to a duplication of part of the lambda chromosome. The genetic instability of these partial diploid strains is due to homologous genetic recombindation between the two identical copies of the phage DNA comprising the duplication. The galactose operon and the duplication of phage DNA carried by these strains is located between the phage lambda P and Q genes.
87 citations
TL;DR: Lambdoid phages form clear plaques and show reduced ability to establish immunity in strains of Escherichia coli that lack adenylate cyclase or catabolite activator protein.
Abstract: Lambdoid phages form clear plaques and show reduced ability to establish immunity in strains of Escherichia coli that lack adenylate cyclase or catabolite activator protein. The absence of the activator protein or cyclic AMP reduces the frequency of lysogenization, but does not prevent steady-state repressor synthesis of a lysogen. Lambda phage mutants able to form turbid plaques on strains that lack catabolite activator protein or adenylate cyclase have been isolated and analyzed.
78 citations
TL;DR: DNA synthesis enhances recombinant particle formation more in some map intervals than in others, especially in regions having the larger amounts of recombination-associated synthesis.
Abstract: Recombination in some intervals of the map of phage lambda is associated with more DNA synthesis than in other intervals. Blockage of DNA synthesis by high temperature in a host temperature-sensitive for DNA synthesis results in the relative reduction of recombinant frequencies in those regions having the larger amounts of recombination-associated synthesis. Reduction of DNA synthesis at normal temperatures by a combination of the bacterial mutation and a mutation in one of the phage genes required for DNA synthesis has the same consequence. Therefore, DNA synthesis enhances recombinant particle formation more in some map intervals than in others.
45 citations
TL;DR: In this article, the A-specific modification is brought about by DNA methylation and the sAo mutation not only abolished the affinity for a-specific restriction, but also for A specific modification.
Abstract: Bacteria with A-specific restriction plate unmodified phage λ with an efficiency of 10-2. One mutational event can produce restriction insensitive (sAo) mutants of λ. These differ from the original sA form of λ by no other property than their response to A-host specificity. Two-parental phage crosses involving sA and sAo, respectively, as non-selective marker allowed to map sA between genes cII and O. These data indicate that sA is the only site on λDNA with affinity for A-specific restriction. λDNA is thus an interesting substrate in in vitro A-specific restriction and modification. Using an assay based on the infectivity of λDNA on helper-infected bacteria, A-specific modification activity was found in partially purified sonicates of bacteria with A-host specificity. In parallel to modification, 3H-methyl label from s-adenosylmethionine, the only cofactor required for modification, was transferred to unmodified λDNA. No association of radioactivity was observed in control experiments with DNA from either modified λ·A or from aλsAo mutant. These data suggest that A-specific modification is brought about by DNA methylation and that the sAo mutation not only abolished the affinity for A-specific restriction, but also for A-specific modification.
45 citations
TL;DR: The existence of the amber mutant provides further evidence that rex and cI are distinct genes, since it seems to be identical to wild-type lambda in its ability to establish or maintain lysogeny.
Abstract: Twenty-five rex− mutants of phage lambda have been isolated. Three of the mutants, including one amber mutant, map at three distinct sites within the rex region of the lambda genetic map. The existence of the amber mutant provides further evidence that rex and cI are distinct genes, since it seems to be identical to wild-type lambda in its ability to establish or maintain lysogeny.
39 citations
TL;DR: Lambda bacteriophage was used to infect human fibroblasts and viral specific RNA was detected by hybridization with lambda DNA and a correlation was found between the amount of virus used in each infection and the percentage of lambda-specific RNA produced.
35 citations
TL;DR: If lambda phage heads are exposed to micrococcal nuclease before phage tails are attached, the cohesive ends of the packaged λ DNA are damaged and the altered ends were used as templates for repair synthesis catalyzed by Escherichia coli DNA polymerase I.
28 citations
TL;DR: The inactivation kinetics of two different Lambda phage repressors in lysogenic complexes of an E. coli strain temperature sensitive in DNA synthesis is investigated and it is inferred that after a stop of DNA synthesis effector molecules are accumulated which give rise to the inactivation of phagerepressors directly.
Abstract: The inactivation kinetics of two different Lambda phage repressors in lysogenic complexes of an E. coli strain temperature sensitive in DNA synthesis is investigated. From the experimental data obtained it is inferred that
1.
after a stop of DNA synthesis effector molecules are accumulated which give rise to the inactivation of phage repressors directly,
2.
the accumulation kinetics of the effector molecules after a stop of DNA synthesis is similar to that kinetics which must be expected from accumulation of DNA precursors.
3.
The inactivation of λ+ and λind8repressor molecules begins 20 min and 5 min, respectively, after the stop of host DNA synthesis.
4.
The effector concentration is rapidly diminished after restoration of DNA synthesis,
5.
the accumulation of effector molecules proceeds without protein synthesis in this strain after temperature shift up.
6.
The effector substance seems not to be a protein.
25 citations
TL;DR: A mutant has been isolated from E. coli AB1157 which increases up to 13 fold the rate of clear plaque mutations of extracellularly UV-irradiated phage λ, and the presence of a recA allel in a mul mutant abolishes the UV-mutability of phages λ.
Abstract: A mutant (called mul) has been isolated from E. coli AB1157 which increases up to 13 fold the rate of clear plaque mutations of extracellularly UV-irradiated phage λ. The mul-mutation does not affect the UV-mutability of T4rII mutants or various bacterial markers and therefore seems to act specifically on UV-irradiated phage λ. However, when spheroplasts prepared from mul cells were infected with either irradiated or unirradiated λ-DNA equal frequencies of clear plaques were produced. As there is indirect evidence (host cell reactivation) that the spheroplasts do not significantly exclude irradiated phage DNA it seems that the mul phenotype can be expressed only in complete cells.
20 citations
TL;DR: The tandem duplication structure can explain why an addition mutant in a recombination-proficient host produces a series of phages whose DNA lengths differ, each from the next, by an amount equal to the primary DNA addition.
TL;DR: Hybrids between Escherichia coli K- 12 and Salmonella typhosa which conserved a continuous K-12 chromosomal diploid segment extending from pro through ara to the strA locus were sensitive to plaque formation by wild-type lambda, establishing that S. typhosa does not perform the K-13 modification of lambda deoxyribonucleic acid.
Abstract: Hybrids between Escherichia coli K-12 and Salmonella typhosa which conserved a continuous K-12 chromosomal diploid segment extending from pro through ara to the strA locus were sensitive to plaque formation by wild-type lambda. These partially diploid S. typhosa hybrids could be lysogenized with lambda and subsequently induced to produce infectious phage particles. When the K-12 genes were segregated from a lysogenic S. typhosa hybrid, phage-productive ability was no longer detectable due to loss of a genetic region necessary for vegetative replication of lambda. However, lambda prophage was shown to persist in a quiescent state in the S. typhosa hybrid segregant with phage-productive ability being reactivated after replacement of the essential K-12 lambda replication region. Low-frequency transduction and high-frequency transduction lysates containing the gal(+) genes of S. typhosa were prepared by induction of lambda-lysogenic S. typhosa hybrids indicating that the attlambda site is chromosomally located in S. typhosa in close proximity to the gal locus as in E. coli K-12. After propagation in S. typhosa hybrids, lambda was subject to restriction by E. coli K-12 recipients, thus establishing that S. typhosa does not perform the K-12 modification of lambda deoxyribonucleic acid. Hybrids of S. typhosa, however, did not restrict lambda grown previously on E. coli K-12. The K-12 genetic region required for lambda phage production in S. typhosa was located within min 66 to min 72 on the genetic map of the E. coli chromosome. Transfer of an F-merogenote encompassing the 66 to 72 min E. coli chromosomal region to lambda-insensitive S. typhosa hybrids enabled them to replicate wild-type lambda. The lambda-insensitive S. typhosa hybrid, WR4255, which blocks lambda replication, can be mutagenized to yield mutant strains sensitive to lambdavir and lambdaimm434. These WR4255 mutants remained insensitive to plaque formation by wild-type lambda.
TL;DR: It appears possible to estimate the size of a DNA deletion from the phage sedimentation coefficient by substituting 5‐bromouracil for thymine, which gives results consistent with a restriction of the net DNA hydration that depends on the DNA volume.
Abstract: The banding density of phage lambda varies with the activity of water when the phage particles are banded in a series of different cesium salts. The results are comparable to those Hearst and Vinograd for free DNA. Lambda phage ghosts show less net hydration than the phage particles and band in a fairly narrow range of densities in these cesium salts. The phage banding density may be predicted to a first approximation by a simple additive approximation: the total net hydration of the phage is approximately equal to the net hydrations of free λ DNA λ hosts, all measured at the same water activity. The simple additive approximation is not adequate, however, to explain the banding density differences between a deletion mutant and phage lambda in the different cesium salts. The density differences evidently are sensitive to second-order effects: they apparently are affected by a restriction of DNA hydration inside the phage head, which depends both on water activity and on DNA length (or free volume inside the phage head). This becomes a striking effect in Cs2SO4 solutions where the net DNA hydration is large. Changing the phage banding density by substituting 5-bromouracil for thymine, which increases the DNA mass while leaving the DNA volume relatively unchanged, gives results consistent with a restriction of the net DNA hydration that depends on the DNA volume. Data on the sedimentation velocity behavior that λ and λb2 in diferrent salts are presented and discussed. It appears possible to estimate the size of a DNA deletion from the phage sedimentation coefficient.
TL;DR: Adenosine 3',5'-cyclic phosphate is indispensable for formation of the phage lambda receptor in Escherichia coli K-12.
Abstract: Adenosine 3′,5′-cyclic phosphate is indispensable for formation of the phage lambda receptor in Escherichia coli K-12.
TL;DR: The results indicate that the virL is a mutation of operator gene controlling the left- hand operon and virR or virC is that controlling the right-hand operon.
Abstract: SummaryThe effect of the virL, virR or virC mutation (which is related to the virulency of lambda phage) on the gene expression has been studied. The results indicate that the virL is a mutation of operator gene controlling the left-hand operon and virR or virC is that controlling the right-hand operon.
TL;DR: Large amounts of a heat-inducible phage lambda mutant (lambdaCI857) may be obtained under standardized conditions and yield a homogenous population of unbroken lambda DNA molecules.
Abstract: Large amounts of a heat-inducible phage lambda mutant (λCI857) may be obtained under standardized conditions. The phage is harvested by simple polyethylene glycol (C 6000) precipitation and purified by CsCl density gradient banding. Deoxyribonucleic acid (DNA) is extracted by cold phenol and purified by sucrose density gradient sedimentation to yield a homogenous population of unbroken λ DNA molecules.
TL;DR: PDNA was enriched in A-T at low polymerase/DNA ratios (excess DNA) although at higher ratios pDNA did not depart from the base composition of total h DNA.
TL;DR: Under certain conditions, Escherichia coli K12 cells lysogenic for λ can be made sensitive to free phage DNA without the addition of external helper phage.
Abstract: Under certain conditions, Escherichia coli K12 cells lysogenic for λ can be made sensitive to free phage DNA without the addition of external helper phage. This competence depends on the phages released in the growth medium by spontaneous lysis. The kinetics of the decay of this competence are similar to the kinetics of cyclization of injected phage DNA.
TL;DR: It was shown that there are substances with stimulating or inhibiting action, respectively, on the inducibility of prophages and the prophage exhibit different reactions on the exposure of the respective lysogenic strains against some substances tested.
Abstract: The inducibility of the prophages λ+ and λ ind8 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 λ+ and λ inds 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 (λ 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.
TL;DR: DNA extracted from phage lambda grown on Escherichia coli K-12 strain W4032 had 113 +/- 10 5-methylcytosine residues and 215 +/- 20 6-methyl adenine residues per genome, as determined by three independent methods.
Abstract: Deoxyribonucleic acid (DNA) extracted from phage lambda grown on Escherichia coli K-12 strain W4032 had 113 +/- 10 5-methylcytosine residues and 215 +/- 20 6-methyl adenine residues per genome, as determined by three independent methods. These methylated nucleotides were distributed equally among the two strands of lambda DNA. Shearing of double-stranded DNA to half-length fragments revealed a slight deficiency of 5-methyl cytosine in the 55% guanine plus cytosine half. Shearing the DNA to fragments of smaller length showed that the distribution of methylated nucleotides along the double helix was uniform with the exception of an undermethylated fragment arising from the center of the lambda DNA molecule. The implication of these results for the function of methylated nucleotides in the lambda DNA molecule is discussed.
TL;DR: Density gradient analysis of purified lambda phage particles after storage reveals that minor species with new banding desities arise during storage, which have densities expected for phage‐ghost clusters containing integra rations of ghosts tophage particles.
Abstract: Density gradient analysis of purified lambda phage particles after storage reveals that minor species with new banding desities arise during storage. These have densities expected for phage-ghost clusters containing integra rations of ghosts to phage particles. A lage numbersof new banding species has been observed.
Journal Article•
TL;DR: In this paper, the effect of virL mutation on gene expression was studied and it was shown that λvirL mutant expressed the N gene function but not the 0 gene function as analyzed by the method of hetero-immune phage complementation in the presence of λ repressor.
Abstract: The effect of virL mutation on the gene expression was studied. λvirL mutant expresses the N gene function but not the 0 gene function as analysed by the method of hetero-immune phage complementation in the presence of λ repressor. The λ specific exonuclease which is induced by the N gene product was produced by λvirL in λcIts lysogen. VirL region may be an operator region of the left-hand operon.