title: DNA binding is essential for PprI function in response to radiation damage in Deinococcus radiodurans.
abstract: The extremely radioresistant bacterium Deinococcus radiodurans possesses a rapid and efficient but poorly known DNA damage response mechanism that mobilizes one-third of its genome to survive lethal radiation damage. Deinococcal PprI serves as a general switch to regulate the expression of dozens of proteins from different pathways after radiation, including the DNA repair proteins RecA, PprA and SSB. However, the underlying mechanism is poorly understood. In this study, we analyzed the dynamic alteration in global transcriptional profiles in wildtype and pprI mutant strains by combining microarrays and time-course sampling. We found that PprI up-regulated transcription of at least 210 genes after radiation, including 21 DNA repair and replication-related genes. We purified PprI and a helix-turn-helix (HTH) domain mutant and found that PprI specifically bound to the promoters of recA and pprA in vitro but did not bind nonspecific double-strand DNA. Chromatin immunoprecipitation (ChIP) assays confirmed that PprI specifically interacted with the promoter DNA of recA and pprA after radiation. Finally, we showed that a DNA-binding activity-deficient pprI mutant only partially restored resistance of the pprI mutant strain to γ radiation, UV radiation, and mitomycin C. Taken together, these results indicate that DNA-binding activity is essential for PprI to program the DNA repair process and cellular survival of D. radiodurans in response to radiation damage.
authors: Institute of Nuclear-Agricultural Sciences, Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China.
authors: Huiming
authors: H
authors: Lu
authors: Huan
authors: H
authors: Chen
authors: Guangzhi
authors: G
authors: Xu
authors: Amir Miraj-Ul-Hussain
authors: AM
authors: Shah
authors: Yuejin
authors: Y
authors: Hua
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004249:DNA Damage; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism*; D034301:Deinococcus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects*; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000528:radiation effects; D011485:Protein Binding / Q000187:drug effects / Q000528:radiation effects; D017434:Protein Structure, Tertiary; D011938:Rec A Recombinases / Q000378:metabolism; D018085:Regulon / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects; D015854:Up-Regulation / Q000187:drug effects / Q000528:radiation effects
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011938:Rec A Recombinases