title: Proximity of Radiation Desiccation Response Motif to the core promoter is essential for basal repression as well as gamma radiation-induced gyrB gene expression in Deinococcus radiodurans.
abstract: The radioresistant D. radiodurans regulates its DNA damage regulon (DDR) through interaction between a 17bp palindromic cis-regulatory element called the Radiation Desiccation Response Motif (RDRM), the DdrO repressor and a protease IrrE. The role of RDRM in regulation of DDR was dissected by constructing RDRM sequence-, position- or deletion-variants of Deinococcal gyrB gene (DR0906) promoter and by RDRM insertion in the non-RDRM groESL gene (DR0606) promoter, and monitoring the effect of such modifications on the basal as well as gamma radiation inducible promoter activity by quantifying fluorescence of a GFP reporter. RDRM sequence-variants revealed that the conservation of sequence at the 5th and 13th position and the ends of RDRM is essential for basal repression by interaction with DdrO. RDRM position-variants showed that the sequence acts as a negative regulatory element only when located around transcription start site (TSS) and within the span of RNA polymerase (RNAP) binding region. RDRM deletion-variants indicated that the 5' sequence of RDRM possibly possesses an enhancer-like element responsible for higher expression yields upon repressor clearance post-irradiation. The results suggest that RDRM plays both a negative as well as a positive role in the regulation of DDR in D. radiodurans.
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.
authors.forename: Narasimha
authors.initials: N
authors.lastname: Anaganti
authors.affiliation: Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India. Electronic address: bbasu@barc.gov.in.
authors.forename: Bhakti
authors.initials: B
authors.lastname: Basu
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.
authors.forename: Rita
authors.initials: R
authors.lastname: Mukhopadhyaya
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400085, India. Electronic address: aptesk@barc.gov.in.
authors.forename: Shree Kumar
authors.initials: SK
authors.lastname: Apte
mesh_terms: D004249:DNA Damage; D027081:DNA Gyrase / Q000235:genetics*; D034301:Deinococcus / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects*; D004742:Enhancer Elements, Genetic; D005720:Gamma Rays; D015964:Gene Expression Regulation, Bacterial; D059372:Nucleotide Motifs; D011401:Promoter Regions, Genetic; D018085:Regulon
chemical_list: D027081:DNA Gyrase
keywords: Core promoter; Deinococcus radiodurans; RDRM-promoters; Radiation responsive genes; gyrB