Project description:Here, we compared gene expression level by RNA-Seq analysis among a wild-type (WT) Deinococcus geothermalis strain, a dgeo_2840 of LysR family member gene (Δdgeo_2840), a putative Dps dgeo_0257 (Δdgeo_0257), and a cystine importer dgeo_1986-1987 gene disrupted strain (Δdgeo_1986-1987). From this transcriptomic data, we detected dgeo_2840, dgeo_0257, and dgeo_1986-1987 controlling genes which were somehow up-regulated and/or down-regulated. In particular, Deinococcus geothermalis has a total of 73 insertion sequences (ISs) in genomes, and some of them are actively transposed to other loci with replicative mode by the oxidative stress of hydrogen peroxide treatment.
Project description:The extreme radiation resistance of Deinococcus bacteria requires the radiation-stimulated cleavage of protein DdrO by a specific metalloprotease called IrrE. DdrO is the repressor of a predicted radiation/desiccation response (RDR) regulon, composed of radiation-induced genes having a conserved DNA motif (RDRM) in their promoter regions. Here, we showed that addition of zinc ions to purified apo-IrrE, and short exposure of Deinococcus cells to zinc ions, resulted in cleavage of DdrO in vitro and in vivo, respectively. Binding of IrrE to RDRM-containing DNA or interaction of IrrE with DNA-bound DdrO was not observed. The data are in line with IrrE being a zinc peptidase, and indicate that increased zinc availability, caused by oxidative stress, triggers the in vivo cleavage of DdrO unbound to DNA. Transcriptomics and proteomics of Deinococcus deserti confirmed the IrrE-dependent regulation of predicted RDR regulon genes and also revealed additional members of this regulon. Comparative analysis showed that the RDR regulon is largely well conserved in Deinococcus species, but also showed diversity in the regulon composition. Notably, several RDR genes with an important role in radiation resistance in Deinococcus radiodurans, for example pprA, are not conserved in some other radiation-resistant Deinococcus species.
Project description:Deinococcus metallilatus MA1002 was exposed to ultraviolet radiation to generate mutants with enhanced biofilm production. Two strains (nos 5 and 6) were then selected based on their high biofilm formation, as well as their possession of higher concentrations of extracellular matrix components (eDNA, protein and saccharides) than the wild-type (WT). Genomic sequencing revealed the presence of large genome deletions in a secondary chromosome in the mutants. Expression analyses of the WT and mutant strains indicated the upregulation of genes associated with exopolysaccharide synthesis and stress response. The mutant strains showed high mortality in glucose-supplemented (TYG) medium; however, cell death and biofilm formation were not increased in mutant cells grown under acetate- or glyoxylate-added media, suggesting that metabolic toxicity during glucose metabolism induced a high rate of cell death but improved biofilm formation in mutant strains. In damaged cells, eDNAs contributed to the enhanced biofilm formation of D. metallilatus.