Topic
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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TL;DR: It is suggested that RNase III cleavage at the Sib site allows processive exonucleolytic degradation of the RNA to proceed to a region of secondary structure within the Int coding sequence, which protects the upstream region of the transcript from further degradation.
Abstract: Expression of the int gene of bacteriophage lambda from two promoters, pI and pL, is differentially regulated through RNA processing. Efficient Int protein synthesis from the pL RNA is inhibited by the action of sib, a cis-acting retroregulator downstream from the int gene. We have used mapping procedures with nuclease S1 to study the pL transcripts produced in vivo after phage lambda infection. We have found an RNase III-dependent processing site within the Int coding sequence, 387 nucleotides upstream from the site of the primary cleavage by RNase III at Sib. This secondary processing site is located at the most stable region of secondary structure in the sib int region, as predicted by computer analysis. We suggest that RNase III cleavage at the Sib site allows processive exonucleolytic degradation of the RNA to proceed to a region of secondary structure within the Int coding sequence, which protects the upstream region of the transcript from further degradation.
19 citations
TL;DR: An unexpected antibody-dependent, FcgammaRI-mediated enhancement of phage transduction in mammalian cells is revealed, and new approaches to improve bacteriophage-mediated gene transfer are suggested.
19 citations
TL;DR: This region has DNA sequence elements and open reading frames that resemble those found in phages lambda, P22, and phi 80 and encodes homologs of the lambda CII transcription activator, the P22 DNA replication proteins, and a fourth protein of unknown function.
Abstract: We report the sequence of a region of the PR operon of lambdoid phage HK022 and an analysis of the proteins it encodes. This region has DNA sequence elements and open reading frames that resemble those found in phages lambda, P22, and phi 80. The open reading frames encode homologs of the lambda CII transcription activator, the P22 DNA replication proteins, and a fourth protein of unknown function.
18 citations
TL;DR: Evidence suggests that translesion synthesis is the primary component of Weigle reactivation of lambda phage in the absence of excision repair, and could be attributed to some inducible excison repair unable to occur on single-stranded DNA.
Abstract: Agents that interfere with DNA replication in Escherichia coli induce physiological adaptations that increase the probability of survival after DNA damage and the frequency of mutants among the survivors (the SOS response). Such agents also increase the survival rate and mutation frequency of irradiated bacteriophage after infection of treated bacteria, a phenomenon known as Weigle reactivation. In UV-irradiated single-stranded DNA phage, Weigle reactivation is thought to occur via induced, error-prone replication through template lesions (translesion synthesis [P. Caillet-Fauquet, M: Defais, and M. Radman, J. Mol. Biol. 117:95-112, 1977]). Weigle reactivation occurs with higher efficiency in double-stranded DNA phages such as lambda, and we therefore asked if another process, recombination between partially replicated daughter molecules, plays a major role in this case. To distinguish between translesion synthesis and recombinational repair, we studied the early replication of UV-irradiated bacteriophage lambda in SOS-induced and uninduced bacteria. To avoid complications arising from excision of UV lesions, we used bacterial uvrA mutants, in which such excision does not occur. Our evidence suggests that translesion synthesis is the primary component of Weigle reactivation of lambda phage in the absence of excision repair. The greater efficiency in Weigle reactivation of double-stranded DNA phage could thus be attributed to some inducible excision repair unable to occur on single-stranded DNA. In addition, after irradiation, lambda phage replication seems to switch prematurely from the theta mode to the rolling circle mode.
18 citations
TL;DR: The cloned fragment conferring φHAU3 resistance did not make the host DNA prone to degradation during electrophoresis, indicating that the two phenotypes are controlled by different genes which were deleted together from the chromosome of S. lividans ZX1.
Abstract: The DNA of wild-type Streptomyces lividans 66 is degraded during electrophoresis in buffers containing traces of ferrous iron. S. lividans ZX1, a mutant selected for resistance to DNA degradation, simultaneously became sensitive to phi HAU3, a wide-host-range temperate bacteriophage. A DNA fragment conferring phi HAU3 resistance was cloned; it contains a phage resistance gene whose deduced amino acid sequence is similar to the phage lambda Ea59 endonuclease. The S. lividans phi HAU3 resistance does not seem to be a classical restriction-modification system, because no host-modified phages able to propagate on the wild-type strain could be isolated. The cloned fragment did not make the host DNA prone to degradation during electrophoresis, indicating that the two phenotypes are controlled by different genes which were deleted together from the chromosome of ZX1.
18 citations