Project description:Abstract Background The extraordinarily resistant bacterium Deinococcus radiodurans withstands harsh environmental conditions present in outer space. Deinococcus radiodurans was exposed for one year outside the International Space Station within Tanpopo orbital mission to investigate microbial survival and space travel. In addition, a ground-based simulation experiment with conditions, mirroring those from Low Earth orbit, was performed. Methods We monitored Deinococcus radiodurans cells during early stage of recovery after Low Earth orbit exposure using electron microscopy tools. Furthermore, proteomic, transcriptomic and metabolomic analyses were performed to identify molecular mechanisms responsible for the survival of Deinococcus radiodurans in Low Earth orbit. Results D. radiodurans cells exposed to low Earth orbit conditions do not exhibit any morphological damage. However, an accumulation of numerous outer-membrane associated vesicles was observed. On levels of proteins and transcripts, a multifaceted response was detected to alleviate cell stress. The UvrABC endonuclease excision repair mechanism was triggered to cope with DNA damage. Defense against reactive oxygen species is mirrored by the increased abundance of catalases and is accompanied by the increased abundance of putrescine which works as scavenging molecule. In addition, several proteins and mRNAs, responsible for regulatory and transporting functions showed increased abundances. The decrease in primary metabolites indicate alternations in the energy status, which is needed to repair damaged molecules. Conclusion Low Earth orbit induced molecular rearrangements trigger multiple components of metabolic stress response and regulatory networks in exposed microbial cells. Presented results show that the non-sporulating bacterium Deinococcus radiodurans survived long-term Low Earth orbit exposure if wavelength below 200 nm are not present, which mirrors the UV spectrum of Mars, where CO2 effectively provides a shield below 190 nm. These results should be considered in the context of planetary protection concerns and the development of new sterilization techniques for future space missions.
Project description:Transcriptional profiling of Deinococcus radiodurans comparing control untreated wild type cells with wild type cells treated with 100 µM CdCl2.
Project description:This study tracks the proteome during recovery from 10 kGy acute ionizing radiation (IR) in Deinococcus radiodurans R1 (WT). After 1 hour of recovery post-IR exposure, we observed 37 proteins significantly differentially expressed, including several within the Radiation and Dessication Response (RDR) pathway. Additionally, we also explored the regulatory network of a sRNA named PprS (previously Dsr2) in Deinococcus radiodurans by comparing the proteome of a sRNA knockdown strain (PprSKD, which demonstrates a ~2-fold decrease in PprS expression) to WT D. radiodurans during unirradiated conditions at late-exponential phase. Comparison between these two strains demonstrated decreased levels of one of PprS's targets, PprM, in the PprSKD strain which validated the activation mechanism we propose for PprS on pprM.
