PubMed Health⌕ Search

Biomedical subjects

G Gussin

Publications and source records attributed to G Gussin.

6 recordsLinked to original sources
PubMed1990

Selection for mutations in the PR promoter of bacteriophage lambda.

Insertion of DNA containing PR, the early rightward promoter of bacteriophage lambda, is lethal to M13-derived vectors when the promoter directs transcription (using the '+' strand as template) toward the M13 origin of replication (ori). Lethality can be relieved by mutation of PR, repression of the promoter by the lambda cl repressor, or by insertion of a strong transcription terminator between PR and ori. We have used selection for plaque formation in the absence of repressor to isolate 14 different mutations at 8 sites in PR. This method of isolating promoter mutants in vivo is applicable generally to strong promoters whose activity is regulated either positively or negatively.

Bacteriophage lambda↗
PubMed1979

Inactivation of E. coli RNA polymerase by polyriboinosinic acid: heterogeneity of RS complexes.

Polyriboinosinic acid (poly I) inhibits initiation of transcription by binary complexes formed between Adenovirus 2 DNA and E. coli RNA polymerase holoenzyme. In the presence of poly I, just as in the presence of rifampicin, initiation of transcription exhibits a sigmoidal dependence on the temperature at which the binary complexes are formed. This indicates that I (closed) complexes between Ad 2 DNA and RNA polymerase are rapidly inactivated by poly I, but that RS (open) complexes are relatively resistant. However, even among the RS complexes, at least two classes can be distinguished on the basis of the degree to which they are resistant to poly I: RS-1 complexes are somewhat sensitive to poly I (half-time of inactivation approximately 10 min) while RS-2 complexes are almost completely resistant to the inhibitor (half-time of inactivation approximately 10 h). For both types of RS complex, the degree of sensitivity to poly I is ionic strength-dependent.

Adenoviridae↗
PubMed1976

Purification and properties of a DNA-binding protein with characteristics expected for the Cro protein of bacteriophage lambda, a repressor essential for lytic growth.

The Cro protein specified by bacteriophage lambda is a repressor essential for normal lytic growth of the virus, thus having a physiological role distinct from that of cI, the repressor that maintains lysogeny. We have purified a lambda-specific DNA-binding protein with the requirements for synthesis and biochemical activities expected for Cro protein from studies in vivo. As isolated, the protein appears to be a dimer of molecular weight approximately 18,000 with DNA-binding properties that are very similar, but not identical, to those of the cI protein. We infer that bacteriophage lambda uses the same regulatory region of DNA for two different DNA-binding repressor proteins with subtle differences in binding activity specialized for different physiological roles.

Carrier Proteins↗