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PubMed1975

Recognition sequences of repressor and polymerase in the operators of bacteriophage lambda.

Nucleotide sequences in two wild-type and six mutant operators in the DNA of phage lambda are compared. Strikingly similar 17 base pair units are found which we identify as the repressor binding sites. Each operator contains multiple repressor binding sites separated by A-T rich spacers. Elements of 2 fold rotational symmetry are present in each of the sites. Superimposed on each operator is an E. coli RNA polymerase recognition site (promoter). Similarities in the sequences of the two lambda promoters, a lac promoter, and an E. coli RNA polymerase recognition site in SV40 DNA are noted.

Base Sequence↗
PubMed1979

A secondary attachment site for bacteriophage lambda in trpC of E. coli.

We have determined the nucleotide sequence of a secondary lambda attachment site in trpC. Direct sequence analysis of lambdatrp transducing phage DNA fragments carrying the two prophage attachment sites reveals a 6 nucleotide homology in the crossover region which is a subset of the 15 nucleotide core sequence in the primary lambda attachment site: GCTTTTTTATACTAA. This 6 nucleotide sequence is also present in the intact trpC genome at the attachment site, as shown by analysis of trpC mRNA spanning this region.

Base Sequence↗
PubMed1978

Physical mapping of bacteriophage lambda DNA with restriction endonuclease HpaI.

The restriction endonuclease from Haemophilus parainfluenzae, endoR.HpaI cleaves lambdacI857s7 DNA into 14 fragments. The sizes of these fragments were determined and a physical map was constructed. The ordering of the fragments was carried out using different deletion and substitution mutants of lambda phage, double cleavages with another restriction enzyme, endoR.BamHI, and partial protection of individual HpaI recognition sites by the antibiotics distamycin A and actinomycin D. HpaI produces fragments from the left arm of the lambda DNA genome, which may help in investigating the structure and function of this part of the phage.

Chromosome Mapping↗
PubMed1979

Construction of plasmid cloning vehicles that promote gene expression from the bacteriophage lambda pL promoter.

Two multiple-copy, ColE1-type, plasmid cloning vehicles, pHUB2 and pHUB4, have been constructed that carry four different single restriction sites down-stream from the phage lambda promoter pL. The promoting activity of pL is switched off at low temperature in the presence of a cIts gene that specifies a temperature-sensitive repressor but could be activated by heat induction. cIts was located either on the host chromosome, or on a second plasmid pRK248 that is compatible with the cloning vehicle, or on the vehicle itself. Three different restriction fragments, each carrying the gene trpA of Salmonella typhimurium or Shigella dysenteriae, have been inserted into the EcoRI, BamHI and SalI sites, respectively, of these plasmids and pL dependent expression of the inserted gene in Escherichia coli was determined by measuring the enzymatic activity of the trpA gene product. Heat induction resulted in a level of expression of trpA corresponding to 1 to 6.6% of the total soluble cell protein as trpA protein. The level of trpA protein production depended on the particular insert and the plasmid used.

Bacterial Proteins↗