Guanine Quadruplex DNA Regulates Gamma Radiation Response of Genome Functions in the Radioresistant Bacterium Deinococcus radiodurans

Deinococcus radiodurans can recover from extensive DNA damage caused by many genotoxic agents. It lacks LexA/RecA-mediated canonical SOS response. Therefore, the molecular mechanisms underlying the regulation of DNA damage response would be worth investigating in this bacterium.D. radiodurans genome is GC-rich and contains numerous islands of putative guanine quadruplex (G4) DNA structure-forming motifs. Here, we showed thatin vivo stabilization of G4 DNA structures can impair DNA damage response processes inD. radiodurans . Essential cellular processes such as transcription, DNA synthesis, and protein translation, which are also an integral part of the double-strand DNA break repair pathway, are affected by the arrest of G4 DNA structure dynamics. Thus, the role of DNA secondary structures in DNA damage response and radioresistance is demonstrated.