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Lambda phage

About: Lambda phage is a research topic. Over the lifetime, 1609 publications have been published within this topic receiving 84675 citations. The topic is also known as: Enterobacteria phage lambda.


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Journal ArticleDOI
TL;DR: A DNA fragment carrying 85% of the coding sequence of regA has been cloned into the phage lambda leftward promoter PL expression vector pAS1, and a high level of truncated regA protein was produced by nalidixic acid induction.
Abstract: The bacteriophage T4 regA gene codes for a regulatory protein that controls the expression of a number of T4 early genes, apparently at the level of translation. Restriction fragments containing the regA structural gene have been cloned into phage M13, and the nucleotide sequence has been determined. Translation of the DNA sequence predicted that regA protein contains 122 amino acids, with a Mr of 14,620. A DNA fragment carrying 85% of the coding sequence of regA has been cloned into the phage lambda leftward promoter PL expression vector pAS1, and a high level of truncated regA protein was produced by nalidixic acid induction. Protein chemical studies of the truncated regA protein gave results consistent with the nucleotide sequence of the regA gene. Subsequently, an intact regA gene was cloned into plasmid pAS1 and overexpressed. The regA protein produced in this way regulates the level of T4 45 and 44 proteins when their corresponding genes are carried on the same plasmid as the regA gene.

15 citations

Journal ArticleDOI
15 Jul 1988-Gene
TL;DR: A derivative of phage lambda is constructed, called an excision vector, which retains only those functions necessary for conditional maintenance of lysogeny and integration/excision, and illustrates a new class of conditional mutations in which the genotype changes in response to external stimuli.

15 citations

Journal ArticleDOI
TL;DR: Two cell shape-determining genes of Escherichia coli K-12, pbpA, the structural gene for penicillin-binding protein 2, and rodA, whose protein is unknown, were subcloned into plasmid vectors from the transducing phage lambda MAd lip24, which carries the lip-leuS region of the E. coli chromosome.
Abstract: Two cell shape-determining genes of Escherichia coli K-12, pbpA, the structural gene for penicillin-binding protein 2, and rodA, whose protein is unknown, were subcloned into plasmid vectors from the transducing phage lambda MAd lip24, which carries the lip-leuS region of the E. coli chromosome. Plasmids with restriction enzyme-created deletions or transposon Tn5 insertions were isolated, and studies of genetic complementation of these plasmids with chromosomal mutations were carried out. Thus, a physical and genetic map of the rodA-pbpA region was established. The genes rodA and pbpA lie side by side within a 4.4-kilobase-pair region. The size of the rodA gene has been shown to be between 0.86 and 1.6 kilobase pairs; such DNA would encode a protein with a molecular weight between 32,000 and 59,000. Since Tn5 mutagenesis of the rodA gene did not affect the expression of the pbpA gene and vice versa, the genes rodA and pbpA seem to have independent promoters. Analysis of the proteins synthesized from the constructed plasmids in maxicells revealed that the plasmid carrying the pbpA gene encoded penicillin-binding protein 2 and amplification of the protein occurred. The product of the rodA gene was not identified.

15 citations

Journal ArticleDOI
TL;DR: It is concluded that Fis is required, but IHF is only partially required, for short-homology-dependent illegitimate recombination during the formation of lambda bio transducing phage.
Abstract: Specialized transducing particles of phage lambda are formed by illegitimate recombination during prophage induction. We examined the effects of an Esherichia coli int, xis, himA, himD, or fis mutation on illegitimate recombination during formation of lambda Spi- phage, a class of lambda bio transducing phage. This type of phage is distinguishable from the docL and docR particles, which contain one cohesive end and are formed by cutting of the cos site, by plaque formation of lambda bio on Escherichia coli P2 lysogens. The yields of lambda Spi- phage in the int, xis, int-xis deletion, and b2 deletion mutants were about 50- to 200-fold higher than that of the wild-type prophage when bacteria were irradiated with UV light. This result indicates that Int and Xis functions, and the att site, are not required for illegitimate recombination. The yield of lambda Spi- phage in the himA, himD, or fis mutant carrying lambda delta int-xis prophage was 2.6-, 3.3-, or 17-fold lower, respectively, than that in the wild-type bacteria under UV irradiation. Analysis of the nucleotide sequences of the junctions of the transducing phages indicates that recombination at the hotspots, as well as at non-hotspots, takes place between short homologous sequences. Because the growth of infecting phages was not suppressed by the himA, himD, or fis mutation, we conclude that Fis is required, but IHF is only partially required, for short-homology-dependent illegitimate recombination during the formation of lambda bio transducing phage.

15 citations

Journal ArticleDOI
01 Sep 1988-Genetics
TL;DR: The finding that r-chain-bias at the P locus is independent of the orientation of lambda cos and thus also independent of that of active Chi's or Chi-like sequences and of the direction of travel of RecBCD enzyme is reported.
Abstract: Chi is a hotspot for homologous recombination mediated by the RecBCD (Rec) pathway of Escherichia coli. For Rec-mediated recombination of phage lambda, the orientation of lambda cos in the lambda chromosome dictates the direction of travel of RecBCD enzyme through DNA and dictates which orientation of Chi or Chi-like sequences will be active in stimulating recombination. I previously found that Rec-mediated lambda patch heteroduplexes, stimulated by Chi or not, are chain-biased; at the lambda P locus, recombinant information resides on the lambda r chain. This bias exists in the presence or absence of Chi sites. Reported herein is the finding that r-chain-bias at the P locus is independent of the orientation of lambda cos and thus also independent of the orientation of active Chi's or Chi-like sequences and of the direction of travel of RecBCD enzyme. These results disprove previously elaborated models in which a chain-specific nick at Chi initiates recombination, and imply that some other chain-distinguishing process is involved with recombination. Replication and transcription are candidates for such a process.

15 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20226
20219
20209
20195
20188
20177