A computational search was carried out to identify additional targets for the Escherichia coli OxyR transcription factor. This approach predicted OxyR binding sites upstream of dsbG, encoding a periplasmic disulfide bond chaperone-isomerase; upstream of fhuF, encoding a protein required for iron uptake; and within yfdI. DNase I footprinting assays confirmed that oxidized OxyR bound to the predi...

A spontaneous Xanthomonas campestris pv. phaseoli H(2)O(2)-resistant mutant emerged upon selection with 1 mM H(2)O(2). In this report, we show that growth of this mutant under noninducing conditions gave high levels of catalase, alkyl hydroperoxide reductase (AhpC and AhpF), and OxyR. The H(2)O(2) resistance phenotype was abolished in oxyR-minus derivatives of the mutant, suggesting that elevat...

To prevent damage by reactive oxygen species, many bacteria have evolved rapid detection and response systems, including the OxyR regulon. The OxyR system detects reactive oxygen and coordinates the expression of numerous defensive antioxidants. In many bacterial species the coordinated OxyR-regulated response is crucial for in vivo survival. Regulation of the OxyR regulon of Haemophilus influe...

Genome-wide transcriptome profiling was used to reveal hydrogen peroxide (H(2)O(2))-dependent regulatory mechanisms in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. In this study we focused on the role of the OxyR protein, a known regulator of the H(2)O(2) response in bacteria. The transcriptome profiles of R. sphaeroides wild-type and oxyR mutant strains that were exposed...

Simultaneous expression of seven genes in Escherichia coli was measured by a reverse transcription-multiplex PCR fluorescence procedure. Genes studied were (i) oxyR (transcriptional regulator); (ii) katG, dps, gorA, and ahpCF (controlled by OxyR); (iii) sodA (controlled by SoxRS); and (iv) trxA (not related to OxyR or SoxRS). Except for trxA, transcription of all genes was activated during the ...

The plant pathogen Ralstonia solanacearum, which causes bacterial wilt disease, is exposed to reactive oxygen species (ROS) during tomato infection and expresses diverse oxidative stress response (OSR) genes during midstage disease on tomato. The R. solanacearum genome predicts that the bacterium produces multiple and redundant ROS-scavenging enzymes but only one known oxidative stress response...

The Escherichia coli OxyR protein is a transcriptional activator for a number of genes induced in response to low concentrations of hydrogen peroxide. To identify additional OxyR-regulated genes, I cloned a DNA fragment that shows promoter activity regulated by OxyR by direct selection of OxyR-binding DNA fragments. Analyses of the cloned fragment indicate that the grx gene, encoding glutaredox...

Porphyromonas gingivalis is an anaerobic microorganism that inhabits the oral cavity, where oxidative stress represents a constant challenge. A putative transcriptional regulator associated with oxidative stress, an oxyR homologue, is known from the P. gingivalis W83 genome sequence. We used microarrays to characterize the response of P. gingivalis to H2O2 and examine the role of oxyR in the re...

Singlet oxygen ((1)O(2)) is a highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules. The oxyR gene product regulates the expression of the enzymes and proteins that are needed for cellular protection against oxidative stress. In this study, the role of oxyR in cellular defense against a singlet oxygen was investigated using Escherich...

Colonization of the gastrointestinal tract is the first event in Klebsiella pneumoniae nosocomial infections, followed by colonization of the bladder or respiratory tract or entry into the bloodstream. To survive in the host, bacteria must harbor specific traits and overcome multiple stresses. OxyR is a conserved bacterial transcription factor with a key role both in the upregulation of defense...