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Defenses against oxidative damage to cell components are essential for survival of bacterial pathogens during infection, and here we have uncovered that the DmsABC S-/N-oxide reductase is essential for virulence and in-host survival of the human-adapted pathogen, Haemophilus influenzae. In several different infection models, H. influenzae ΔdmsA strains showed reduced immunogenicity as well as lower levels of survival in contact with host cells. Expression of DmsABC was induced in the presence of hypochlorite and paraquat, closely linking this enzyme to defense against host-produced antimicrobials. In addition to methionine sulfoxide, DmsABC converted nicotinamide- and pyrimidine-N-oxide, precursors of NAD and pyrimidine for which H. influenzae is an auxotroph, at physiologically relevant concentrations, suggesting that these compounds could be natural substrates for DmsABC. Our data show that DmsABC forms part of a novel, periplasmic system for defense against host-induced S- and N-oxide stress that also comprises the functionally related MtsZ S-oxide reductase and the MsrAB peptide methionine sulfoxide reductase. All three enzymes are induced following exposure of the bacteria to hypochlorite. MsrAB is required for physical resistance to HOCl and protein repair. In contrast, DmsABC was required for intracellular colonization of host cells and, together with MtsZ, contributed to resistance to N-Chlorotaurine. Our work expands and redefines the physiological role of DmsABC and highlights the importance of different types of S-oxide reductases for bacterial virulence. [ABSTRACT FROM AUTHOR]

The importance of [Mn.sup.2+] for pneumococcal physiology and virulence has been studied extensively. However, the specific cellular role(s) for which [Mn.sup.2+] is required are yet to be fully elucidated. Here, we analyzed the effect of [Mn.sup.2+] limitation on the transcriptome and proteome of Streptococcus pneumoniae D39. This was carried out by comparing a deletion mutant lacking the solute binding protein of the high-affinity [Mn.sup.2+] transporter, pneumococcal surface antigen A (PsaA), with its isogenic wild-type counterpart. We provide clear evidence for the [Mn.sup.2+]-dependent regulation of the expression of oxidative-stress-response enzymes SpxB and [Mn.sup.2+]-SodA and virulence-associated genes pcpA and prtA. We also demonstrate the upregulation of at least one oxidative- and nitrosative-stress-response gene cluster, comprising adhC, nmlR, and czcD, in response to [Mn.sup.2+] stress. A significant increase in 6-phosphogluconate dehydrogenase activity in the psaA mutant grown under [Mn.sup.2+]-replete conditions and upregulation of an oligopeptide ABC permease (AppDCBA) were also observed. Together, the results of transcriptomic and proteomic analyses provided evidence for [Mn.sup.2+] having a central role in activating or stimulating enzymes involved in central carbon and general metabolism. Our results also highlight the importance of high-affinity [Mn.sup.2+] transport by PsaA in pneumococcal competence, physiology, and metabolism and elucidate mechanisms underlying the response to [Mn.sup.2+] stress. doi: 10.1128/JB.00064-10

The [NmlR.sub.sp] transcription factor of Streptococcus pneumoniae is shown to induce adhC (alcohol dehydrogenase) expression in the presence of both formaldehyde and methylglyoxal, [nmlR.sub.sp] and adhC mutant strains display altered and opposite aerobic growth phenotypes. The [nmlR.sub.sp] strain exhibits increased resistance to high oxygen tension, attributable to decreased [H.sub.2][O.sub.2] production, which correlated with downregulation of carbamoyl phosphate synthase (carB). This indicates a possible role for AdhC in aldehyde metabolism and a broader role for [NmlR.sub.sp] in the regulation of carbon metabolism. doi: 10.1128/JB.00383-10

The periplasmic multicopper oxidase (CueO) is involved in copper homeostasis and protection against oxidative stress. Here, we show that the deletion of cueO in uropathogenic Escherichia coli increases its colonization of the urinary tract despite its increased sensitivity to hydrogen peroxide. The cueO deletion mutant accumulated iron with increased efficiency compared to its parent strain; this may account for its advantage in the iron-limited environment of the urinary tract.

Catheter-associated urinary tract infection (CAUTI) is the most common nosocomial infection in the United States. Uropathogenic Escherichia coli (UPEC), the most common cause of CAUTI, can form biofilms on indwelling catheters. Here, we identify and characterize novel factors that affect biofilm formation by UPEC strains that cause CAUTI. Sixty-five CAUTI UPEC isolates were characterized for phenotypic markers of urovirulence, including agglutination and biofilm formation. One isolate, E. coli MS2027, was uniquely proficient at biofilm growth despite the absence of adhesins known to promote this phenotype. Mini-Tn5 mutagenesis of E. coli MS2027 identified several mutants with altered biofilm growth. Mutants containing insertions in genes involved in O antigen synthesis (rmlC and manB) and capsule synthesis (kpsM) possessed enhanced biofilm phenotypes. Three independent mutants deficient in biofilm growth contained an insertion in a gene locus homologous to the type 3 chaperone-usher class fimbrial genes of Klebsiella pneumoniae. These type 3 fimbrial genes (mrkABCDF), which were located on a conjugative plasmid, were cloned from E. coli MS2027 and could complement the biofilm-deficient transconjugants when reintroduced on a plasmid. Primers targeting the mrkB chaperone-encoding gene revealed its presence in CAUTI strains of Citrobacter koseri, Citrobacter freundii, Klebsiella pneumoniae, and Klebsiella oxytoca. All of these mrkB-positive strains caused type 3 fimbria-specific agglutination of tannic acid-treated red blood cells. This is the first description of type 3 fimbriae in E. coli, C. koseri, and C. freundii. Our data suggest that type 3 fimbriae may contribute to biofilm formation by different gram-negative nosocomial pathogens.

New advances are presented in the understanding of defense systems against oxidative stress in Neisseria gonorrhoeae and it is found that some of its defenses have similarities to the paradigm established with Escherichia coli but there are also some other key differences. These differences include the presence of a defense system against superoxide based on manganese ions and a glutathione-dependent system for defense against nitric oxide that is under the control of a novel MerR-like transcriptional regulator.

Metallosphaera sedula is a thermoacidophilic Crenarchaeon which is capable of leaching metals from sulfidic ores. The authors have investigated the presence and expression of genes encoding respiratory complexes in this organism when grown heterotrophically or chemolithotrophically on either sulfur or pyrite. The presence of three gene clusters, encoding two terminal oxidase complexes, the quinol oxidase SoxABCD and the SoxM oxidase supercomplex, and a gene cluster encoding a high-potential cytochrome b and components of a b[c.sub.1] complex analogue (cbsBA-soxL2N gene cluster) was established. Expression studies showed that the soxM gene was expressed to high levels during heterotrophic growth of M. sedula on yeast extract, while the soxABCD mRNA was most abundant in cells grown on sulfur. Reduced-minus-oxidized difference spectra of cell membranes showed cytochrome-related peaks that correspond to published spectra of Sulfolobus-type terminal oxidase complexes. In pyrite-grown cells, expression levels of the two monitored oxidase gene clusters were reduced by a factor of 10-12 relative to maximal expression levels, although spectra of membranes clearly contained oxidase-associated haems, suggesting the presence of additional gene clusters encoding terminal oxidases in M. sedula. Pyrite- and sulfur-grown cells contained high levels of the cbsA transcript, which encodes a membrane-bound cytochrome b with a possible role in iron oxidation or chemolithotrophy. The cbsA gene is not co-transcribed with the soxL2N genes, and therefore does not appear to be an integral part of this b[c.sub.1] complex analogue. The data show for the first time the differential expression of the Sulfolobus-type terminal oxidase gene clusters in a Crenarchaeon in response to changing growth modes. Abbreviation: YE, yeast extract.

The catalytic activity of sulfite dehydrogenase is described. It is shown that this activity can be realized while the enzyme is immobilized to the surface of an electrochemical working electrode.

Research has been conducted on dimethyl sulfoxide reductase from Rhodobacter capsulatus. The construction of the system used for expression site-directed mutants of this reductase in the natural host in order to generate and express dimethyl sulfoxide reductase with Y114F mutantion is described.

Electron paramagnetic resonance spectra( EPR) of purified heterotrimeric dimethyl sulfide dehydrogenase reveal resonances arising from multiple redox centers and a b-type heme. The first EPR spectroscopic characterization of the molybdenum center of the enzyme is presented.

Research has been conducted on the purple phototrophic bacterium Rhodobacter capsulatus. The regulation of the dimethylsulfoxide reductase expression (DMSO) in this bacterium has been investigated and the results indicate that R. capsulatus has a DMSO respiration regulator which is different from DorR and RegA and acts as a DMSO reductase expression's negative regulator.

Research has been conducted on the dimethyl sulfoxide reductase from Rhodobacter capsulatus. The structure of the molybdenum cofactor in this reductase has been investigated via Raman spectroscopy.

Research describes the domain structure of the transcription factor PpsR of the photosynthetic bacterium. The domain architecture is made of three regions: the carboxy terminus which is involved in the DNA binding, central oligomerization region, and the amino terminus with no known function.