Articles written in Journal of Biosciences
Volume 32 Issue 3 April 2007 pp 559-568 Articles
K+, the dominant intracellular cation, is required for various physiological processes like turgor homeostasis, pH regulation etc. Bacterial cells have evolved many diverse K+ transporters to maintain the desired concentration of internal K+. In
Volume 41 Issue 2 June 2016 pp 193-203 Article
A third generation promoter probe shuttle vector pKG was constructed, using the green fluorescent protein as a reporter, for in situ evaluation of Deinococcal promoter activity in Escherichia coli or Deinococcus radiodurans. The construct yielded zero background fluorescence in both the organisms, in the absence of promoter sequences. Fifteen deinococcal promoters, either harbouring Radiation and Desiccation Response Motif (RDRM) or not, were cloned in vector pKG. Only the RDRM-promoter constructs displayed (i) gamma radiation inducible GFP expression in D. radiodurans, following gamma irradiation, (ii) DdrO-mediated repression of GFP expression in heterologous E. coli, or (iii) abolition in GFP induction following gamma irradiation, in pprI mutant of D. radiodurans. Utility of pKG vector for real-time in situ assessment of deinococcal promoter function was, thus, successfully demonstrated.
Volume 46 All articles Published: 3 February 2021 Article ID 0010 Article
The highly radiation-resistant bacterium Deinococcus radiodurans responds to gamma radiation or desiccationthrough the coordinated expression of genes belonging to Radiation and Desiccation Resistance/Response(RDR) regulon. RDR regulon is operated through cis-acting sequence RDRM (Radiation DesiccationResponse Motif), trans-acting repressor DdrO and protease IrrE (also called PprI). The present study evaluatedwhether RDR regulon controls the response of D. radiodurans to various other DNA damaging stressors, towhich it is resistant, such as UV rays, mitomycin C (MMC), methyl methanesulfonate (MMS), ethidiumbromide (EtBr), etc. Activation of 3 RDR regulon genes (ddrB, gyrB and DR1143) was studied by taggingtheir promoter sequences with a highly sensitive GFP reporter. Here we demonstrated that all the DNAdamaging stressors elicited activation of RDR regulon of D. radiodurans in a dose-dependent and RDRM-/IrrE-dependent manner. However, ROS-mediated indirect effects [induced by hydrogen peroxide (H2O2),methyl viologen (MV), heavy metal/metalloid (zinc or tellurite), etc.] did not activate RDR regulon. We alsoshowed that level of activation was inversely proportional to cellular abundance of repressor DdrO. Our datastrongly suggests that direct DNA damage activates RDR regulon in D. radiodurans.
Volume 46, 2021
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