Lysogens of phage HK022 are resistant to infection by phage lambda. Lambda resistance is caused by the action of the HK022 Nun protein, which prematurely terminates early lambda transcripts. We report here that transcription of the nun gene initiates at a constitutive prophage promoter, P(Nun), located just upstream of the protein coding sequence. The 5' end of the transcript was determined by ...

Thermodynamic parameters describing the phage 434 Cro protein have been determined by calorimetry and, independently, by far-UV circular dichroism (CD) measurements of isothermal urea denaturations and thermal denaturations at fixed urea concentrations. These equilibrium unfolding transitions are adequately described by the two-state model. The far-UV CD denaturation data yield average temperat...

The bacteriophage lambda repressor, a protein that maintains the lysogenic state of a bacterium containing a lambda prophage, is cleaved when the lysogen is induced by mitomycin C or ultraviolet light. This cleavage does not occur when induction is prevented by mutational alteration either of the phage repressor or of the host recA gene product. Proteolytic cleavage may be the primary mechanism...

Two deletion-substitution mutations of phage lambda, spi-113 and spi-274, are shown to remove about half of the rightward operator OR. Physiological studies show that spi-113 is still repressible. Thus, the 50 or so nucleotides of OR deleted in this mutant are not absolutely essential for repression. prm-116, which inactivates the promoter essential for the maintenance of lambda repressor synth...

The preparation of phage lambda DNA infecting E. coli K 12 with cationic detergent is described. This DNA infects E. coli spheroblasts with the same efficiency as DNA prepared by phenol methods.

The fate of parental lambda genomes after superinfection of homoimmune lysogenic cells was studied. The data confirm a previous observation that in the presence of the lambda repressor, superinfecting lambda DNA does not become associated with replication sites on the bacterial cell membrane. Under these conditions, the nonreplicating, superinfecting phage genomes do not become associated with ...

We present a model to describe electrical conductivity along the DNA double helix. In this model, DNA is considered as a one-dimensional disordered system, and electrons are transported via variable range hopping between localized states. Thermal structural fluctuations in DNA further localize electronic wave functions, giving rise to a temperature-dependent localization length. The model quant...

Bacteriophage Mu d1 (lac Aprr) was used to obtain strains of Escherichia coli K-12 in which the lac genes are expressed from the promoter of pheA, the structural gene for the enzyme chorismate mutase P-prephenate-dehydratase. A derivative of bacteriophage lambda which carries the pheA-lac fusion was prepared; the method used is generally applicable for the construction, from Mu dl lysogens, of ...

The development of the molecular biology of bacteriophage such as T4, lambda and filamentous phages was described and the process that the fundamental knowledge obtained in this field has subsequently led us to the technology of phage display was introduced.