Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.99.3 (PRE)
 1,923 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lysogenic development by bacteriophage lambda is known to require the coordinate expression of two phage operons. Coordinate control is achieved by a positive regulatory mechanism which activates transcription from the promoters of these operons, PRE and PI. The positive effector is the phage regulatory protein cII. We now identify and characterize a third cII-dependent transcription unit on phage lambda, which is positioned in the middle of the Q regulatory gene and has an anti-Q orientation. We demonstrate the cII-dependent function of this promoter and precisely map its 5' transcription start-site both in vitro and in vivo. Most importantly, we show that cII binding and transcription activation at PaQ occur at essentially the same cII levels as those required for PRE and PI activation, and that all three promoters respond to cII at the same time following phage infection. In addition, DNase protection studies demonstrate that cII selectively interacts with the same TTGCN6TTGC DNA sequence repeat in the -35 region of PaQ which cII interacts with at both PRE and PI. We find that cII also binds other TTGCN6TTGC repeat sequences on lambda but binding at these sites does not lead to productive transcription. We conclude that PaQ functions in concert with PRE and PI to regulate the lysogenic growth response of phage lambda. We presume that the PaQ directed anti-sense Q RNA transcript functions to down-regulate the expression of the Q gene, which is needed for the expression of all phage late genes during lytic growth.
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PMID:Characterization of a third, cII-dependent, coordinately activated promoter on phage lambda involved in lysogenic development. 293 30

Irradiation of dominant marker DNA with UV light (150 to 1,000 J/m2) was found to stimulate the transformation of human cells by this marker from two- to more than fourfold. This phenomenon is also displayed by xeroderma pigmentosum cells (complementation groups A and F), which are deficient in the excision repair of UV-induced pyrimidine dimers in the DNA. Also, exposure to UV of the transfected (xeroderma pigmentosum) cells enhanced the transfection efficiency. Removal of the pyrimidine dimers from the DNA by photoreactivating enzyme before transfection completely abolished the stimulatory effect, indicating that dimer lesions are mainly responsible for the observed enhancement. A similar stimulation of the transformation efficiency is exerted by 2-acetoxy-2-acetylaminofluorene modification of the DNA. No stimulation was found after damaging vector DNA by treatment with DNase or gamma rays. These findings suggest that lesions which are targets for the excision repair pathway induce the increase in transformation frequency. The stimulation was found to be independent of sequence homology between the irradiated DNA and the host chromosomal DNA. Therefore, the increase of the transformation frequency is not caused by a mechanism inducing homologous recombination between these two DNAs. UV treatment of DNA before transfection did not have a significant effect on the amount of DNA integrated into the xeroderma pigmentosum genome.
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PMID:UV stimulation of DNA-mediated transformation of human cells. 399 Jun 93