Radiation desiccation response motif-like sequences are involved in transcriptional activation of the Deinococcal ssb gene by ionizing radiation but not by desiccation.
J Bacteriol 2010;
192:5637-44. [PMID:
20802034 DOI:
10.1128/jb.00752-10]
[Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Single-stranded-DNA binding protein (SSB) levels during poststress recovery of Deinococcus radiodurans were significantly enhanced by (60)Co gamma rays or mitomycin C treatment but not by exposure to UV rays, hydrogen peroxide (H₂O₂), or desiccation. Addition of rifampin prior to postirradiation recovery blocked such induction. In silico analysis of the ssb promoter region revealed a 17-bp palindromic radiation/desiccation response motif (RDRM1) at bp -114 to -98 and a somewhat similar sequence (RDRM2) at bp -213 to -197, upstream of the ssb open reading frame. Involvement of these cis elements in radiation-responsive ssb gene expression was assessed by constructing transcriptional fusions of edited versions of the ssb promoter region with a nonspecific acid phosphatase encoding reporter gene, phoN. Recombinant D. radiodurans strains carrying such constructs clearly revealed (i) transcriptional induction of the ssb promoter upon irradiation and mitomycin C treatment but not upon UV or H₂O₂ treatment and (ii) involvement of both RDRM-like sequences in such activation of SSB expression, in an additive manner.
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