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Transcriptional specificity after mycobacteriophage I3 infection

Nagaraja, V and Gopinathan, KP (1987) Transcriptional specificity after mycobacteriophage I3 infection. In: Journal of Biosciences, 11 (1-4). pp. 167-179.

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Transcriptional regulation following mycobacteriophage I3 infection was investigated. For this purpose, RNA polymerase mutants (rifr) of the host bacterium, Mycobacterium smegmatis, were isolated and characterized. Phage growth in rifsand rifr cells in the presence of rifampicin revealed the involvement of host RNA polymerase in phage genome transcription. This was confirmed by studies on in vivo RNA synthesis as well as by direct RNA polymerase assay after phage infection. Significant stimulation in RNA polymerase activity was seen following phage infection. The maximal levels were attained in about 60 min post infection and maintained throughout the phage development period. The stimulation of polymerase activity was most pronounced when the phage DNA was used as the template. RNA polymerases from uninfected and phage-infected M. smegmatis were purified to homogeneity. Enzyme purifn. was accomplished by a rapid procedure utilizing affinity chromatog. on rifampicin-Sepharose columns. Subunit structure anal. of the purified RNA polymerase from uninfected and phage-infected cells showed the presence of \alpha, \beta, \beta' and \sigma subunits similar to the other prokaryotic RNA polymerases. In addn., a polypeptide of 79,000 daltons was assocd. with the enzyme after phage infection. The enzymes differed in their properties with respect to template specificity. Phage I3 DNA was the preferred template for the modified RNA polymerase isolated from infected cells, which may account for the transcriptional switch required for phage development.

Item Type: Journal Article
Publication: Journal of Biosciences
Publisher: The Indian Academy of Sciences
Additional Information: Copyright belongs to the Indian Academy of Sciences
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 19 Mar 2008
Last Modified: 27 Aug 2008 13:13
URI: http://eprints.iisc.ac.in/id/eprint/13232

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