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: An ampicillin-resistant transductant of E. coli HB101 was found to possess mannose-resistant hemagglutinating activity associated with a 50-kilobase-pair plasmid, and both strains agglutinated human erythrocytes in the presence of D-mannose and failed to produce fimbriae after incubation at 18 degrees C.
Abstract: Chromosomal DNA from a uropathogenic strain of Escherichia coli was partially digested with the restriction enzyme EcoRI. The partial digests were ligated into a cosmid containing an ampicillin-resistant determinant and packaged into lambda phage particles. An ampicillin-resistant transductant of E. coli HB101 was found to possess mannose-resistant hemagglutinating activity associated with a 50-kilobase-pair plasmid. Subcloning of the mannose-resistant fimbrial genes revealed that the genetic determinants were encoded by a 6.9-kilobase-pair DNA fragment of a recombinant plasmid. Chimeric plasmids smaller in size were unable to transform E. coli to fimbrial production. Physical maps of the recombinant plasmids were prepared showing restriction endonuclease sites within the inserted DNA fragments. The hemagglutinating activities of the wild-type strain and of the recombinant derivative were compared. Both strains agglutinated human erythrocytes in the presence of D-mannose to the same degree and also failed to produce fimbriae after incubation at 18 degrees C. Also, both strains were agglutinated by antifimbrial serum at a high titer, whereas no such activity was observed when a strain of E. coli which did not possess a plasmid was used.
94 citations
TL;DR: High-resolution restriction maps derived from a rapid restriction mapping protocol based on linearization of circular cosmid DNA in vitro were used to identify and align the cosmids, to localise the position of repetitive sequences, and to interpret the results of electron microscopy heteroduplex experiments.
94 citations
TL;DR: The isolation of three sigma mutants that caused defects in repressor-stimulated, but not basal, transcription from PRM are reported, suggesting that lambda repressor interacts directly with this helix-turn-helix motif in facilitating the formation of a productive initiating complex.
Abstract: The phage lambda repressor activates transcription of its own gene from the promoter PRM. Previous work has suggested that this activation involves a protein-protein interaction between DNA-bound repressor and RNA polymerase. To identify the subunit of RNA polymerase that participates in this putative interaction, we searched for polymerase mutants that responded poorly to repressor. We report here the isolation of three sigma mutants that caused defects in repressor-stimulated, but not basal, transcription from PRM. These mutants bear amino acid substitutions in a putative helix-turn-helix motif that sigma uses to recognize the promoter -35 region. We suggest that lambda repressor interacts directly with this helix-turn-helix motif in facilitating the formation of a productive initiating complex.
94 citations
TL;DR: By assaying expression of proteins that are hybrids between beta-galactosidase and IS50R proteins, it is found that the regulation of transposition cannot be due to the inhibitor repressing synthesis of Tn5 proteins.
94 citations
TL;DR: A phage lambda gene, called tof, responsible for the turnoff of λ-exonuclease synthesis during the lytic cycle has been located in the region of the lambda genome which is nonhomologous with the λi 434 genome.
94 citations