SPOIIIE - Word Related Documents




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842400.9335Postseptational chromosome partitioning in bacteria. Mutations in the spoIIIE gene prevent proper partitioning of one chromosome into the developing prespore during sporulation but have no overt effect on partitioning in vegetatively dividing cells. However, the expression of spoIIIE in vegetative cells and the occurrence of genes closely related to spoIIIE in a range of nonsporulating eubacteria suggested a more general function for the protein. Here we show that SpoIIIE protein is needed for optimal chromosome partitioning in vegetative cells of Bacillus subtilis when the normal tight coordination between septation and nucleoid partitioning is perturbed or when septum positioning is altered. A functional SpoIIIE protein allows cells to recover from a state in which their chromosome has been trapped by a closing septum. By analogy to its function during sporulation, we suggest that SpoIIIE facilitates partitioning by actively translocating the chromosome out of the septum. In addition to enhancing the fidelity of nucleoid partitioning, SpoIIIE also seems to be required for maximal resistance to antibiotics that interfere with DNA metabolism. The results have important implications for our understanding of the functions of genes involved in the primary partitioning machinery in bacteria and of how septum placement is controlled.19957567988
842510.9286Carotenoid biosynthesis in extremophilic Deinococcus-Thermus bacteria. Bacteria from the phylum Deinococcus-Thermus are known for their resistance to extreme stresses including radiation, oxidation, desiccation and high temperature. Cultured Deinococcus-Thermus bacteria are usually red or yellow pigmented because of their ability to synthesize carotenoids. Unique carotenoids found in these bacteria include deinoxanthin from Deinococcus radiodurans and thermozeaxanthins from Thermus thermophilus. Investigations of carotenogenesis will help to understand cellular stress resistance of Deinococcus-Thermus bacteria. Here, we discuss the recent progress toward identifying carotenoids, carotenoid biosynthetic enzymes and pathways in some species of Deinococcus-Thermus extremophiles. In addition, we also discuss the roles of carotenoids in these extreme bacteria.201020832321
60520.9268Conservation and diversity of the IrrE/DdrO-controlled radiation response in radiation-resistant Deinococcus bacteria. 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.201728397370
60630.9266Coexistence of SOS-Dependent and SOS-Independent Regulation of DNA Repair Genes in Radiation-Resistant Deinococcus Bacteria. Deinococcus bacteria are extremely resistant to radiation and able to repair a shattered genome in an essentially error-free manner after exposure to high doses of radiation or prolonged desiccation. An efficient, SOS-independent response mechanism to induce various DNA repair genes such as recA is essential for radiation resistance. This pathway, called radiation/desiccation response, is controlled by metallopeptidase IrrE and repressor DdrO that are highly conserved in Deinococcus. Among various Deinococcus species, Deinococcus radiodurans has been studied most extensively. Its genome encodes classical DNA repair proteins for error-free repair but no error-prone translesion DNA polymerases, which may suggest that absence of mutagenic lesion bypass is crucial for error-free repair of massive DNA damage. However, many other radiation-resistant Deinococcus species do possess translesion polymerases, and radiation-induced mutagenesis has been demonstrated. At least dozens of Deinococcus species contain a mutagenesis cassette, and some even two cassettes, encoding error-prone translesion polymerase DnaE2 and two other proteins, ImuY and ImuB-C, that are probable accessory factors required for DnaE2 activity. Expression of this mutagenesis cassette is under control of the SOS regulators RecA and LexA. In this paper, we review both the RecA/LexA-controlled mutagenesis and the IrrE/DdrO-controlled radiation/desiccation response in Deinococcus.202133923690
58340.9263MarR family proteins sense sulfane sulfur in bacteria. Members of the multiple antibiotic resistance regulator (MarR) protein family are ubiquitous in bacteria and play critical roles in regulating cellular metabolism and antibiotic resistance. MarR family proteins function as repressors, and their interactions with modulators induce the expression of controlled genes. The previously characterized modulators are insufficient to explain the activities of certain MarR family proteins. However, recently, several MarR family proteins have been reported to sense sulfane sulfur, including zero-valent sulfur, persulfide (R-SSH), and polysulfide (R-SnH, n ≥ 2). Sulfane sulfur is a common cellular component in bacteria whose levels vary during bacterial growth. The changing levels of sulfane sulfur affect the expression of many MarR-controlled genes. Sulfane sulfur reacts with the cysteine thiols of MarR family proteins, causing the formation of protein thiol persulfide, disulfide bonds, and other modifications. Several MarR family proteins that respond to reactive oxygen species (ROS) also sense sulfane sulfur, as both sulfane sulfur and ROS induce the formation of disulfide bonds. This review focused on MarR family proteins that sense sulfane sulfur. However, the sensing mechanisms reviewed here may also apply to other proteins that detect sulfane sulfur, which is emerging as a modulator of gene regulation.202438948149
54750.9262Dual role of OhrR as a repressor and an activator in response to organic hydroperoxides in Streptomyces coelicolor. Organic hydroperoxide resistance in bacteria is achieved primarily through reducing oxidized membrane lipids. The soil-inhabiting aerobic bacterium Streptomyces coelicolor contains three paralogous genes for organic hydroperoxide resistance: ohrA, ohrB, and ohrC. The ohrA gene is transcribed divergently from ohrR, which encodes a putative regulator of MarR family. Both the ohrA and ohrR genes were induced highly by various organic hydroperoxides. The ohrA gene was induced through removal of repression by OhrR, whereas the ohrR gene was induced through activation by OhrR. Reduced OhrR bound to the ohrA-ohrR intergenic region, which contains a central (primary) and two adjacent (secondary) inverted-repeat motifs that overlap with promoter elements. Organic peroxide decreased the binding affinity of OhrR for the primary site, with a concomitant decrease in cooperative binding to the adjacent secondary sites. The single cysteine C28 in OhrR was involved in sensing oxidants, as determined by substitution mutagenesis. The C28S mutant of OhrR bound to the intergenic region without any change in binding affinity in response to organic peroxides. These results lead us to propose a model for the dual action of OhrR as a repressor and an activator in S. coelicolor. Under reduced conditions, OhrR binds cooperatively to the intergenic region, repressing transcription from both genes. Upon oxidation, the binding affinity of OhrR decreases, with a concomitant loss of cooperative binding, which allows RNA polymerase to bind to both the ohrA and ohrR promoters. The loosely bound oxidized OhrR can further activate transcription from the ohrR promoter.200717586628
842660.9260Ionizing radiation responses appear incidental to desiccation responses in the bdelloid rotifer Adineta vaga. BACKGROUND: The remarkable resistance to ionizing radiation found in anhydrobiotic organisms, such as some bacteria, tardigrades, and bdelloid rotifers has been hypothesized to be incidental to their desiccation resistance. Both stresses produce reactive oxygen species and cause damage to DNA and other macromolecules. However, this hypothesis has only been investigated in a few species. RESULTS: In this study, we analyzed the transcriptomic response of the bdelloid rotifer Adineta vaga to desiccation and to low- (X-rays) and high- (Fe) LET radiation to highlight the molecular and genetic mechanisms triggered by both stresses. We identified numerous genes encoding antioxidants, but also chaperones, that are constitutively highly expressed, which may contribute to the protection of proteins against oxidative stress during desiccation and ionizing radiation. We also detected a transcriptomic response common to desiccation and ionizing radiation with the over-expression of genes mainly involved in DNA repair and protein modifications but also genes with unknown functions that were bdelloid-specific. A distinct transcriptomic response specific to rehydration was also found, with the over-expression of genes mainly encoding Late Embryogenesis Abundant proteins, specific heat shock proteins, and glucose repressive proteins. CONCLUSIONS: These results suggest that the extreme resistance of bdelloid rotifers to radiation might indeed be a consequence of their capacity to resist complete desiccation. This study paves the way to functional genetic experiments on A. vaga targeting promising candidate proteins playing central roles in radiation and desiccation resistance.202438273318
58770.9259The Nramp (Slc11) proteins regulate development, resistance to pathogenic bacteria and iron homeostasis in Dictyostelium discoideum. The Dictyostelium discoideum genome harbors two genes encoding members of the Nramp superfamily, which is conserved from bacteria (MntH proteins) to humans (Slc11 proteins). Nramps are proton-driven metal ion transporters with a preference for iron and manganese. Acquisition of these metal cations is vital for all cells, as they act as redox cofactors and regulate key cellular processes, such as DNA synthesis, electron transport, energy metabolism and oxidative stress. Dictyostelium Nramp1 (Slc11a1), like its mammalian ortholog, mediates resistance to infection by invasive bacteria. We have extended the analysis to the nramp2 gene, by generating single and double nramp1/nramp2 knockout mutants and cells expressing GFP fusion proteins. In contrast to Nramp1, which is recruited to phagosomes and macropinosomes, the Nramp2 protein is localized exclusively in the membrane of the contractile vacuole, a vesicular tubular network regulating cellular osmolarity. Both proteins colocalize with the V-H(+)-ATPase, which can provide the electrogenic force for vectorial transport. Like nramp1, nramp2 gene disruption affects resistance to Legionella pneumophila. Disrupting both genes additionally leads to defects in development, with strong delay in cell aggregation, formation of large streams and multi-tipped aggregates. Single and double mutants display differential sensitivity to cell growth under conditions of iron overload or depletion. The data favor the hypothesis that Nramp1 and Nramp2, under control of the V-H(+)-ATPase, synergistically regulate iron homeostasis, with the contractile vacuole possibly acting as a store for metal cations.201322992462
54680.9258Resistance to organic hydroperoxides requires ohr and ohrR genes in Sinorhizobium meliloti. BACKGROUND: Sinorhizobium meliloti is a symbiotic nitrogen-fixing bacterium that elicits nodules on roots of host plants Medicago sativa. During nodule formation bacteria have to withstand oxygen radicals produced by the plant. Resistance to H2O2 and superoxides has been extensively studied in S. meliloti. In contrast resistance to organic peroxides has not been investigated while S. meliloti genome encodes putative organic peroxidases. Organic peroxides are produced by plants and are highly toxic. The resistance to these oxygen radicals has been studied in various bacteria but never in plant nodulating bacteria. RESULTS: In this study we report the characterisation of organic hydroperoxide resistance gene ohr and its regulator ohrR in S. meliloti. The inactivation of ohr affects resistance to cumene and ter-butyl hydroperoxides but not to hydrogen peroxide or menadione in vitro. The expression of ohr and ohrR genes is specifically induced by organic peroxides. OhrR binds to the intergenic region between the divergent genes ohr and ohrR. Two binding sites were characterised. Binding to the operator is prevented by OhrR oxidation that promotes OhrR dimerisation. The inactivation of ohr did not affect symbiosis and nitrogen fixation, suggesting that redundant enzymatic activity exists in this strain. Both ohr and ohrR are expressed in nodules suggesting that they play a role during nitrogen fixation. CONCLUSIONS: This report demonstrates the significant role Ohr and OhrR proteins play in bacterial stress resistance against organic peroxides in S. meliloti. The ohr and ohrR genes are expressed in nodule-inhabiting bacteroids suggesting a role during nodulation.201121569462
813990.9254TAL effectors: highly adaptable phytobacterial virulence factors and readily engineered DNA-targeting proteins. Transcription activator-like (TAL) effectors are transcription factors injected into plant cells by pathogenic bacteria of the genus Xanthomonas. They function as virulence factors by activating host genes important for disease, or as avirulence factors by turning on genes that provide resistance. DNA-binding specificity is encoded by polymorphic repeats in each protein that correspond one-to-one with different nucleotides. This code has facilitated target identification and opened new avenues for engineering disease resistance. It has also enabled TAL effector customization for targeted gene control, genome editing, and other applications. This article reviews the structural basis for TAL effector-DNA specificity, the impact of the TAL effector-DNA code on plant pathology and engineered resistance, and recent accomplishments and future challenges in TAL effector-based DNA targeting.201323707478
8421100.9253Dynamic stepwise opening of integron attC DNA hairpins by SSB prevents toxicity and ensures functionality. Biologically functional DNA hairpins are found in archaea, prokaryotes and eukaryotes, playing essential roles in various DNA transactions. However, during DNA replication, hairpin formation can stall the polymerase and is therefore prevented by the single-stranded DNA binding protein (SSB). Here, we address the question how hairpins maintain their functional secondary structure despite SSB's presence. As a model hairpin, we used the recombinogenic form of the attC site, essential for capturing antibiotic-resistance genes in the integrons of bacteria. We found that attC hairpins have a conserved high GC-content near their apical loop that creates a dynamic equilibrium between attC fully opened by SSB and a partially structured attC-6-SSB complex. This complex is recognized by the recombinase IntI, which extrudes the hairpin upon binding while displacing SSB. We anticipate that this intriguing regulation mechanism using a base pair distribution to balance hairpin structure formation and genetic stability is key to the dissemination of antibiotic resistance genes among bacteria and might be conserved among other functional hairpins.201728985409
6110.9248YprA family helicases provide the missing link between diverse prokaryotic immune systems. Bacteria and archaea possess an enormous variety of antivirus immune systems that often share homologous proteins and domains, some of which contribute to diverse defense strategies. YprA family helicases are central to widespread defense systems DISARM, Dpd, and Druantia. Here, through comprehensive phylogenetic and structural prediction analysis of the YprA family, we identify several major, previously unrecognized clades, with unique signatures of domain architecture and associations with other genes. Each YprA family clade defines a distinct class of defense systems, which we denote ARMADA (disARM-related Antiviral Defense Array), BRIGADE (Base hypermodification and Restriction Involving Genes encoding ARMADA-like and Dpd-like Effectors), or TALON (TOTE-like and ARMADA-Like Operon with Nuclease). In addition to the YprA-like helicase, ARMADA systems share two more proteins with DISARM. However, ARMADA YprA homologs are most similar to those of Druantia, suggesting ARMADA is a 'missing link' connecting DISARM and Druantia. We show experimentally that ARMADA protects bacteria against a broad range of phages via a direct, non-abortive mechanism. We also discovered multiple families of satellite phage-like mobile genetic elements that often carry both ARMADA and Druantia Type III systems and show that these can provide synergistic resistance against diverse phages.202541000832
72120.9244R gene-controlled host specificity in the legume-rhizobia symbiosis. Leguminous plants can enter into root nodule symbioses with nitrogen-fixing soil bacteria known as rhizobia. An intriguing but still poorly understood property of the symbiosis is its host specificity, which is controlled at multiple levels involving both rhizobial and host genes. It is widely believed that the host specificity is determined by specific recognition of bacterially derived Nod factors by the cognate host receptor(s). Here we describe the positional cloning of two soybean genes Rj2 and Rfg1 that restrict nodulation with specific strains of Bradyrhizobium japonicum and Sinorhizobium fredii, respectively. We show that Rj2 and Rfg1 are allelic genes encoding a member of the Toll-interleukin receptor/nucleotide-binding site/leucine-rich repeat (TIR-NBS-LRR) class of plant resistance (R) proteins. The involvement of host R genes in the control of genotype-specific infection and nodulation reveals a common recognition mechanism underlying symbiotic and pathogenic host-bacteria interactions and suggests the existence of their cognate avirulence genes derived from rhizobia. This study suggests that establishment of a root nodule symbiosis requires the evasion of plant immune responses triggered by rhizobial effectors.201020937853
545130.9244Characterization of the organic hydroperoxide resistance system of Brucella abortus 2308. The organic hydroperoxide resistance protein Ohr has been identified in numerous bacteria where it functions in the detoxification of organic hydroperoxides, and expression of ohr is often regulated by a MarR-type regulator called OhrR. The genes annotated as BAB2_0350 and BAB2_0351 in the Brucella abortus 2308 genome sequence are predicted to encode OhrR and Ohr orthologs, respectively. Using isogenic ohr and ohrR mutants and lacZ promoter fusions, it was determined that Ohr contributes to resistance to organic hydroperoxide, but not hydrogen peroxide, in B. abortus 2308 and that OhrR represses the transcription of both ohr and ohrR in this strain. Moreover, electrophoretic mobility shift assays and DNase I footprinting revealed that OhrR binds directly to a specific region in the intergenic region between ohr and ohrR that shares extensive nucleotide sequence similarity with so-called "OhrR boxes" described in other bacteria. While Ohr plays a prominent role in protecting B. abortus 2308 from organic hydroperoxide stress in in vitro assays, this protein is not required for the wild-type virulence of this strain in cultured murine macrophages or experimentally infected mice.201222821968
543140.9243OxyR2 Modulates OxyR1 Activity and Vibrio cholerae Oxidative Stress Response. Bacteria have developed capacities to deal with different stresses and adapt to different environmental niches. The human pathogen Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, utilizes the transcriptional regulator OxyR to activate genes related to oxidative stress resistance, including peroxiredoxin PrxA, in response to hydrogen peroxide. In this study, we identified another OxyR homolog in V. cholerae, which we named OxyR2, and we renamed the previous OxyR OxyR1. We found that OxyR2 is required to activate its divergently transcribed gene ahpC, encoding an alkylhydroperoxide reductase, independently of H(2)O(2) A conserved cysteine residue in OxyR2 is critical for this function. Mutation of either oxyR2 or ahpC rendered V. cholerae more resistant to H(2)O(2) RNA sequencing analyses indicated that OxyR1-activated oxidative stress-resistant genes were highly expressed in oxyR2 mutants even in the absence of H(2)O(2) Further genetic analyses suggest that OxyR2-activated AhpC modulates OxyR1 activity by maintaining low intracellular concentrations of H(2)O(2) Furthermore, we showed that ΔoxyR2 and ΔahpC mutants were less fit when anaerobically grown bacteria were exposed to low levels of H(2)O(2) or incubated in seawater. These results suggest that OxyR2 and AhpC play important roles in the V. cholerae oxidative stress response.201728138024
58150.9243A Conserved Basal Transcription Factor Is Required for the Function of Diverse TAL Effectors in Multiple Plant Hosts. Many Xanthomonas bacteria use transcription activator-like effector (TALE) proteins to activate plant disease susceptibility (S) genes, and this activation contributes to disease. We recently reported that rice basal transcription factor IIA gamma subunit, OsTFIIAγ5, is hijacked by TALE-carrying Xanthomonas oryzae infecting the plants. However, whether TFIIAγs are also involved in TALE-carrying Xanthomonas-caused diseases in other plants is unknown. Here, molecular and genetic approaches were used to investigate the role of TFIIAγs in other plants. We found that TFIIAγs are also used by TALE-carrying Xanthomonas to cause disease in other plants. The TALEs of Xanthomonas citri pv. citri (Xcc) causing canker in citrus and Xanthomonas campestris pv. vesicatoria (Xcv) causing bacterial spot in pepper and tomato interacted with corresponding host TFIIAγs as in rice. Transcriptionally suppressing TFIIAγ led to resistance to Xcc in citrus and Xcv in pepper and tomato. The 39th residue of OsTFIIAγ5 and citrus CsTFIIAγ is vital for TALE-dependent induction of plant S genes. As mutated OsTFIIAγ5(V 39E), CsTFIIAγ(V 39E), pepper CaTFIIAγ(V 39E), and tomato SlTFIIAγ(V 39E) also did not interact with TALEs to prevent disease. These results suggest that TALE-carrying bacteria share a common mechanism for infecting plants. Using TFIIAγ(V 39E)-type mutation could be a general strategy for improving resistance to TALE-carrying pathogens in crops.201729163628
8137160.9241Modulation of Bacterial Fitness and Virulence Through Antisense RNAs. Regulatory RNAs contribute to gene expression control in bacteria. Antisense RNAs (asRNA) are a class of regulatory RNAs that are transcribed from opposite strands of their target genes. Typically, these untranslated transcripts bind to cognate mRNAs and rapidly regulate gene expression at the post-transcriptional level. In this article, we review asRNAs that modulate bacterial fitness and increase virulence. We chose examples that underscore the variety observed in nature including, plasmid- and chromosome-encoded asRNAs, a riboswitch-regulated asRNA, and asRNAs that require other RNAs or RNA-binding proteins for stability and activity. We explore how asRNAs improve bacterial fitness and virulence by modulating plasmid acquisition and maintenance, regulating transposon mobility, increasing resistance against bacteriophages, controlling flagellar production, and regulating nutrient acquisition. We conclude with a brief discussion on how this knowledge is helping to inform current efforts to develop new therapeutics.202033747974
582170.9241Sulfane Sulfur Is a Strong Inducer of the Multiple Antibiotic Resistance Regulator MarR in Escherichia coli. Sulfane sulfur, including persulfide and polysulfide, is produced from the metabolism of sulfur-containing organic compounds or from sulfide oxidation. It is a normal cellular component, participating in signaling. In bacteria, it modifies gene regulators to activate the expression of genes involved in sulfur metabolism. However, to determine whether sulfane sulfur is a common signal in bacteria, additional evidence is required. The ubiquitous multiple antibiotic resistance regulator (MarR) family of regulators controls the expression of numerous genes, but the intrinsic inducers are often elusive. Recently, two MarR family members, Pseudomonas aeruginosa MexR and Staphylococcus aureus MgrA, have been reported to sense sulfane sulfur. Here, we report that Escherichia coli MarR, the prototypical member of the family, also senses sulfane sulfur to form one or two disulfide or trisulfide bonds between two dimers. Although the tetramer with two disulfide bonds does not bind to its target DNA, our results suggest that the tetramer with one disulfide bond does bind to its target DNA, with reduced affinity. An MarR-repressed mKate reporter is strongly induced by polysulfide in E. coli. Further investigation is needed to determine whether sulfane sulfur is a common signal of the family members, but three members sense cellular sulfane sulfur to turn on antibiotic resistance genes. The findings offer additional support for a general signaling role of sulfane sulfur in bacteria.202134829649
344180.9238Identification of genes in Rhizobium leguminosarum bv. trifolii whose products are homologues to a family of ATP-binding proteins. The specific interaction between rhizobia and their hosts requires many genes that influence both early and late steps in symbiosis. Three new genes, designated prsD, prsE (protein secretion) and orf3, were identified adjacent to the exo133 mutation in a cosmid carrying the genomic DNA of Rhizobium leguminosarum bv. trifolii TA1. The prsDE genes share significant homology to the genes encoding ABC transporter proteins PrtDE from Erwinia chrysanthemi and AprDE from Pseudomonas aeruginosa which export the proteases in these bacteria. PrsD shows at least five potential transmembrane hydrophobic regions and a large hydrophilic domain containing an ATP/GTP binding cassette. PrsE has only one potential transmembrane hydrophobic domain in the N-terminal part and is proposed to function as an accessory factor in the transport system. ORF3, like PrtF and AprF, has a typical N-terminal signal sequence but has no homology to these proteins. The insertion of a kanamycin resistance cassette into the prsD gene of the R. leguminosarum bv. trifolii TA1 wild-type strain created a mutant which produced a normal amount of exopolysaccharide but was not effective in the nodulation of clover plants.19979141701
607190.9235A novel copper-sensing two-component system for inducing Dsb gene expression in bacteria. In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here, we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa; in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation (Dsb) (i.e., the dsbDEG operon and dsbB). In the absence of copper, DsbS acts as a phosphatase toward DsbR, thus blocking the transcription of Dsb genes. In the presence of copper, the metal ion directly binds to the sensor domain of DsbS, and the Cys82 residue plays a critical role in this process. The copper-binding behavior appears to inhibit the phosphatase activity of DsbS, leading to the activation of DsbR. The copper resistance of the dsbRS knock-out mutant is restored by the ectopic expression of the dsbDEG operon, which is a DsbRS major target. Strikingly, cognates of the dsbRS-dsbDEG pair are widely distributed across eubacteria. In addition, a DsbR-binding site, which contains the consensus sequence 5'-TTA-N(8)-TTAA-3', is detected in the promoter region of dsbDEG homologs in these species. These findings suggest that the regulation of Dsb genes by DsbRS represents a novel mechanism by which bacterial cells cope with copper stress.202236546013