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: The aga gene coding for alpha-galactosidase in Streptococcus mutans was detected in a recombinant gene library constructed in phage lambda and indicated that the enzyme functions as a tetramer.
Abstract: The aga gene coding for alpha-galactosidase in Streptococcus mutans was detected in a recombinant gene library constructed in phage lambda. The gene was subcloned into plasmid vectors and shown to specify a novel protein of Mr 80,000. Characterization of alpha-galactosidase from S. mutans and from recombinant Escherichia coli expressing aga indicated that the enzyme functions as a tetramer. The amino acid composition of the alpha-galactosidase, deduced from nucleotide sequencing of aga, gave a predicted Mr of 82,022 and revealed regions of homology to alpha-galactosidases encoded by the E. coli Raf plasmids and by Bacillus stearothermophilus. Inactivation of the aga gene in S. mutans resulted in loss of all alpha-galactosidase activity and abolished the ability to ferment melibiose; alpha-glucosidase activity was also lost, due to an indirect effect on the dexB gene.
44 citations
TL;DR: The extent of DNA sequence required to form a bacterial attachment site (attB) that functions in bacteriophage lambda integration is investigated and it is found that the common core sequence plus the adjoining 4-bp sequences of both the B and B' arms are required for full activity.
Abstract: We have investigated the extent of DNA sequence required to form a bacterial attachment site (attB) that functions in bacteriophage lambda integration. A DNA fragment carrying attB of Escherichia coli was trimmed, recloned and tested for recombination proficiency. We found that the common core sequence plus the adjoining 4-bp sequences of both the B and B' arms are required for full activity, while plasmids with an even shorter attB sequence retain some capacity to function as attB in vivo. We also found that the nonspecific DNA that is joined to the required attachment site sequence does not significantly influence the rate of the recombination reaction.
44 citations
TL;DR: The bimolecular complexes are shown to represent a synaptic intermediate in the reaction in which Int protein promotes the IHF‐independent recombination of two attL sites, and should enable a detailed analysis of synapsis for this pathway.
Abstract: Bacteriophage lambda uses site-specific recombination to move its DNA into and out of the Escherichia coli genome. The recombination event is mediated by the recombinase integrase (Int) together with several accessory proteins through short specific DNA sequences known as attachment sites. A gel mobility shift assay has been used to show that, in the absence of accessory proteins, Int can align and hold together two DNA molecules, each with an attachment site, to form stable non-covalent 'bimolecular complexes'. Each attachment site must have both core and arm binding sites for Int to participate in a bimolecular complex. These stable structures can be formed between pairs of attL and attP attachment sites, but cannot include attB or attR sites; they are inhibited by integration host factor (IHF) protein. The bimolecular complexes are shown to represent a synaptic intermediate in the reaction in which Int protein promotes the IHF-independent recombination of two attL sites. These complexes should enable a detailed analysis of synapsis for this pathway.
43 citations
TL;DR: Results strongly suggest that a rather large segment of the LamB polypeptide is exposed at the outer face of the outer membrane, which would bear the epitopes for the four available anti‐LamB monoclonal antibodies that react with the cell surface, and part of the binding site for phage lambda.
Abstract: The Escherichia coli LamB protein is located in the outer membrane. It is both a component of the maltose and maltodextrin transport system, and the receptor for phages lambda and K10. It is a trimer composed of three identical polypeptide chains, each containing 421 residues. Six independent mutants have been isolated, in which the LamB protein is altered in its interaction with one or more monoclonal antibodies specific for regions of the protein that are exposed at the cell surface. Some of the mutations also altered the binding site for phage lambda. All of the mutations were clustered in the same region of the lamB gene, corresponding to residues 333-394 in the polypeptide. This and previous results strongly suggest that a rather large segment of the LamB polypeptide, extending from residue 315 to 401, is exposed at the outer face of the outer membrane. This segment would bear the epitopes for the four available anti-LamB monoclonal antibodies that react with the cell surface, and part of the binding site for phage lambda.
43 citations
TL;DR: The identification of the membrane-containing phage PRD1 holin gene (gene XXXV) is described and the charged amino acids at the protein C terminus are involved in the timing of host cell lysis.
Abstract: Holin proteins are phage-induced integral membrane proteins which regulate the access of lytic enzymes to host cell peptidoglycan at the time of release of progeny viruses by host cell lysis. We describe the identification of the membrane-containing phage PRD1 holin gene (gene XXXV). The PRD1 holin protein (P35, 12.8 kDa) acts similarly to its functional counterpart from phage lambda (gene S), and the defect in PRD1 gene XXXV can be corrected by the presence of gene S of lambda. Several nonsense, missense, and insertion mutations in PRD1 gene XXXV were analyzed. These studies support the overall conclusion that the charged amino acids at the protein C terminus are involved in the timing of host cell lysis.
43 citations