Project description:Sensing of ROS is essential for cellular response to oxidative stress. While oxidative stress response in bacteria and eukaryotes has been extensively studied, less is known about the mechanism in archaea. In this study, we demonstrate that deletion of sisperR, a gene encoding the PerR of the model hyperthermophilic archaeon Saccharolobus islandicus abolishes the oxidative stress-induced expression of a large number of genes. ΔsisperR exhibits enhanced tolerance to H2O2 treatment. Consistently, SisPerR overexpression leads to hypersensitivity to of the cells to the H2O2 treatment. We show that the expression of Dps and MntH which are involved in the regulation of cellular metal ion homeostasis, but not that of ROS scavenging enzymes, is significantly up-regulated with H2O2 treatment and repressed by SisPerR. In summary, this study has established that SisPerR is a repressive redox-sensing transcription factor regulating the intracellular metal ion homeostasis in Saccharolobus islandicus for the oxidative stress defense.
Project description:In Sulfolobales cells, transcription of the Ups (UV-inducible pili of Sulfolobus) and Ced (Crenarchaeal system for exchange of DNA) genes is highly induced by DNA damage, and the two systems play key roles in pili-mediated cell aggregation and chromosomal DNA import, respectively. Ups is composed of UpsA, UpsB, UpsE, and UpsF, while Ced is composed of CedA, CedA1, CedA2, and CedB. So far, how DNA is transported by these systems is far from clear. Here, we report three novel components of the Ced and Ups systems in Saccharolobus islandicus REY15A, CedD (SiRe_1715) and CedE (SiRe_2100), paralogs of CedB and CedA, and UpsC (SiRe_1957), a paralog of UpsA/UpsB. We developed a DNA import and export assay method, by which we revealed that CedD, CedE, and UpsC are essential for DNA import, while CedE and UpsC are also involved in DNA export together with CedA1 and Ups. Microscopic analysis revealed that upsC is involved in cell aggregation like other Ups genes. In addition, we found that cedB and cedD co-occur in the Crenarchaeal genomes that lack virB4, an essential component of type IV secretion system. Interestingly, CedB and CedD share homology to different parts of VirB4 N-terminal domain and form stable homo-oligomers in vitro. Collectively, our results indicate that CedD, CedE, and UpsC are integral components of the Ced and Ups systems in Sulfolobales.
