Project description:Deinococcus deserti is a desiccation- and radiation-tolerant desert bacterium. Differential RNA sequencing was performed to explore the specificities of its transcriptome. Strikingly, for 1174 (60%) mRNAs the transcription start site was found exactly at (916 cases, 47%) or very close to the translation initiation codon AUG or GUG. Such proportion of leaderless mRNAs, which may resemble ancestral mRNAs, is unprecedented for a bacterial species. Proteomics showed that leaderless mRNAs are efficiently translated in D. deserti. Interestingly, we also found 173 additional transcripts with a 5’-AUG or 5’-GUG that would make them competent for ribosome binding and translation into novel small polypeptides. Fourteen of these are predicted to be leader peptides involved in transcription attenuation. Another 30 correlated with new gene predictions and/or showed conservation with annotated and non-annotated genes in other Deinococcus species, and five of these novel polypeptides were indeed detected by mass spectrometry. The data also allowed re-annotation of the start codon position of 257 genes, including several DNA repair genes. Moreover, several novel highly radiation-induced genes were found and their potential roles are discussed. Based on our RNA sequencing and proteogenomics data, we propose that translation of many of the novel leaderless transcripts, which may have resulted from single nucleotide changes and maintained by selective pressure, provides a new explanation for the generation of a cellular pool of small peptides important for protection of proteins against oxidation and thus for radiation/desiccation tolerance and adaptation to harsh environmental conditions.
Project description:Transcriptomic analysis was performed in Deinococcus geothermalis wild-type and three mutants including dgeo_0257, dgeo_0281, and double knockout (DK) mutants. dgeo_0281 is a major Dps-coding gene and dgeo_0257 is a novel Dps candidate. Thus, to detecte physiological functions of both Dps-encoded genes, each gene-disrupted mutant and DK mutant was constructed and performed RNA-Seq analysis. This result support better understanding for Dps roles in radiation resistant bacterium through up-regulated and down-regulated genes profile.
Project description:Radiation-resistant Deinococcus radiodurans is an extreme microorganism capable of withstanding high levels of ionizing radiation and chemical mutagens. It possesses remarkable DNA repair capabilities and serves as a model organism for studying stress resistance mechanisms. However, our understanding of the relationship between the biological characteristics of this species and its chromosomal 3D structure remains limited. In this study, we employed chromosome conformation capture and sequencing (3C-seq) technology to determine the 3D genome structure of D. radiodurans and to further investigate the changes of chromosome conformation induced by ultraviolet irradiation. We observed that the overall chromatin folding structure of the cells became much looser after UV irradiation, with smaller chromosomal interaction domains (CIDs) merging to form larger CIDs. Integrating transcriptomic data analysis, we found that the majority of upregulated differentially expressed genes were significantly enriched near specific CID boundaries. Additionally, we comprehensively elucidated that Dr_ebfC as a nuclear-associated protein, serves as a global regulatory factor in gene expression processes and may modulate transcriptional regulation by altering chromosomal structure, thereby influencing the physiological state of the bacterium. Overall, our study provides insights into the chromosomal conformational changes of D. radiodurans under different conditions, offering valuable resources for further understanding the molecular mechanisms underlying its extreme resistance.