Project description:Deinococcus radiodurans is an extremophilic microorganism that possesses a unique DNA damage repair system, conferring strong resistance to radiation, desiccation, oxidative stress, and chemical damage. Recently, we discovered that D. radiodurans possesses a N4-methylation (m4C) methyltransferase called M.DraR1, which recognizes the 5'-CCGCGG-3' sequence and methylates the second cytosine. Here, we revealed its cognate restriction endonuclease R.DraR1 and recognized that it is the only endonuclease specially for non-4C-methylated 5'-CCGCGG-3' sequence so far. We designated the particular m4C R.DraR1-M.DraR1 as DraI R-M system. Bioinformatics searches displayed the rarity of the DraI R-M homologues system. Meanwhile, recombination and transformation efficiency experiments demonstrated the important role of the DraI R-M system in response to oxidative stress. Besides, in vitro activity experiments showed that R.DraR1 could exceptionally cleave DNA substrates with m5C-methlated 5'-CCGCGG-3' sequence besides its routine activity, suggesting that this particular R-M component possesses a broader substrate choice. Furthermore, an imbalance of the DraI R-M system led to cell death through regulating genes involved in the maintenance of cell survival such as genome stability, transporter, energy production. Thus, our research revealed a novel m4C R-M system that plays key roles in maintaining cell viability and defending foreign DNA in D. radiodurans.
Project description:Purpose: DNA methylation has a global impact on gene expression Methods: Gene expression profiles of D. radiodurans R1 wild type and ΔM.DraR1 strains were generated by deep sequencing using Illumina HiSeqTM2500. Results: RNA-seq was used for differential expression gene analysis between wild-type and ΔM.DraR1 strains. A total of 1158 genes (766 upregulated genes and 392 downregulated genes) were differentially expressed in ΔM.DraR1 strain. GO enrichment analysis revealed that upregulated unigenes were significantly enriched in twelve subcategories. The majority of unigenes in the biological process category were associated with macromolecule metabolic processes. Interestingly, a number of unigenes were also associated with DNA recombination. Within the molecular function category, most unigenes were assigned to nucleic acid, DNA binding and hydrolase, and nucleoside triphosphatase activity. The KEGG enrichment analytical scatter diagram showed that the major pathways affected in the deletion strain belonged to ABC transport, two-component systems, DNA replication, homologous recombination, and protein export pathways. The majority of DNA damage response genes, such as ddrA, ddrB, ddrO, ddrG, ddrJ, ddrK, ddrD and pprA, were significantly upregulated. Several genes involved in DNA recombinational repair pathway including recA, recO, rexD, and ruvB were also significantly upregulated. Putative competence genes, including those encoding prepilin peptidase, CRP and CinA, were upregulated in the mutant strain. This gene expression pattern of the ΔM.DraR1 strain resembled that of D. radiodurans during recovery after exposure to acute radiation, indicating that the absence of N4-cytosine DNA methylation may result in intracellular stress. Conclusion: Absence of N4-cytosine DNA Methylation in D. radiodurans Leads to Expression Changes of Proteins Involved in DNA Damage Response
Project description:N 4-methylcytosine (4mC) is a natural DNA modification occurring in thermophiles and plays important roles in restriction-modification (R-M) systems in bacterial genomes. However, the precise location and sequence context of 4mC in the whole genome are limited. In this study, we developed an APOBEC3A-mediated deamination sequencing (4mC-AMD-seq) method for genome-wide mapping of 4mC at single-base resolution. In the 4mC-AMD-seq method, cytosine and 5-methylcytosine (5mC) are deaminated by APOBEC3A (A3A) protein to generate uracil and thymine, both of which are read as thymine in sequencing, while 4mC is resistant to deamination and therefore read as cytosine. Thus, the readouts of cytosines from sequencing could manifest the original 4mC sites in genomes. With the 4mC-AMD-seq method, we achieved the genome-wide mapping of 4mC in Deinococcus radiodurans (D. radiodurans). In addition, we confirmed that 4mC, but not 5mC, was the major modification in the D. radiodurans genome. We identified 1586 4mC sites in the genome of D. radiodurans, among which 564 sites were located in the CCGCGG motif. The average methylation levels in the CCGCGG motif and non-CCGCGG sequence were 70.0% and 22.8%, respectively. We envision that the 4mC-AMD-seq method will facilitate the investigation of 4mC functions, including the 4mC-involved R-M systems, in uncharacterized but potentially useful strains.
Project description:Transcriptional profiling of Deinococcus radiodurans comparing control untreated wild type cells with wild type cells treated with 100 µM CdCl2.
Project description:Transcriptional profiling of Deinococcus radiodurans comparing control wild type cells with bphPR deletion mutant were treated with MMC (5 μg/ml)
Project description:Transcriptional profiling of Deinococcus radiodurans comparing control untreated wild type cells with wild type cells treated with 0.3M NaCl or 2M NaCl
Project description:In this study, we mapped the DdrO regulon in Deinococcus radiodurans by using two genome-scale approaches, ChIP-seq and RNA-seq analyses. These approaches were performed to find additional DdrO targets sites that were not predicted by previous in silico analyses. To our knowledge, we present here the first ChIP-seq analysis performed at the genome level in D. radiodurans. Alignments of DNA sequences extracted from ChIP-seq analysis were also performed to compare the consensus motif found to the predicted DdrO-binding motif. Our results show that the RDR regulon in D. radiodurans is more complex than previously thought and is composed of at least 35 genes, including such DNA and RNA metabolism proteins as RecG and HelD helicases, and the prokaryotic replicative DNA ligase LigA, but also new genes associated with different metabolic pathways, involved in translation or encoding proteins of unknown function.
Project description:Deinococcus radiodurans exposed to higher doses of gamma radiation showed induced levels of DRB0091 polypeptide annotated as a putative response regulator in an operon expressing upstream to DRB0090, histidine kinase. Deletion of drB0090 generated, showed decreased tolerance to DNA damage and impairment in DSB repair. Recombinant DR0090 protein showed phosphotransferase activity on its cognate response regulator, DRB0091. The drb0090 deletion mutant was checked for its role in regulation of gene expression in response to DNA damage in Deinococcus radiodurans R1. The gene expression profiling of this mutant was carried out by complete transcriptome analysis of these cells grown under normal as well as upon gamma-irradiated conditions and compared with wild type cells. DRB0090 mutant showed extreme sensitivity to gamma radiation and was used for Gene expression profiling using microarray and compared with wild type data.
Project description:IrrE is a unique gene in Deinococcus, which is the switch of DNA repair and celluar surival network. Expressing IrrE enhanced the salt tolence in E. coli. To understand the effect of IrrE to E. coli during salt shock, we constructed the IrrE-expressing plasmid pMG1-IrrE. And pMG1 is the empty vector used as a control. The GroESL promoter was amplified from D. radiodurans R1 genomic DNA by PCR with proper primers. The PCR product was ligated into the T-cloning site of T-vector pMD18T, generating the plasmid pMG1.