Tremblay P-L, Lovley DR.. Role of the NiFe hydrogenase Hya in oxidative stress defense in Geobacter sulfurreducens. J Bacteriol 194: 2248-2253

Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA.
Journal of bacteriology (Impact Factor: 2.81). 02/2012; 194(9):2248-53. DOI: 10.1128/JB.00044-12
Source: PubMed


Geobacter sulfurreducens, an Fe(III)-reducing deltaproteobacterium found in anoxic subsurface environments, contains 4 NiFe hydrogenases. Hyb, a periplasmically oriented membrane-bound NiFe hydrogenase, is essential for hydrogen-dependent growth. The functions of the three other hydrogenases are unknown. We show here that the other periplasmically oriented membrane-bound NiFe hydrogenase, Hya, is necessary for growth after exposure to oxidative stress when hydrogen or a highly limiting concentration of acetate is the electron source. The beneficial impact of Hya on growth was dependent on the presence of H(2) in the atmosphere. Moreover, the Hya-deficient strain was more sensitive to the presence of superoxide or hydrogen peroxide. Hya was also required to safeguard Hyb hydrogen oxidation activity after exposure to O(2). Overexpression studies demonstrated that Hya was more resistant to oxidative stress than Hyb. Overexpression of Hya also resulted in the creation of a recombinant strain better fitted for exposure to oxidative stress than wild-type G. sulfurreducens. These results demonstrate that one of the physiological roles of the O(2)-resistant Hya is to participate in the oxidative stress defense of G. sulfurreducens.

Download full-text


Available from: Pier-Luc Tremblay,
12 Reads
  • Source
    • "Some electron-transferring proteins highly abundant at low growth rates were also related to protection against oxidative stress (e.g. Gmet 3330 [38], Gmet 1930 [27], etc.) (Fig. 5). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The strict anaerobe Geobacter metallireducens was cultivated in retentostats under acetate and acetate plus benzoate limitation in the presence of Fe(III) citrate in order to investigate its physiology under close to natural conditions. Growth rates below 0.003 h−1 were achieved in the course of cultivation. A nano-liquid chromatography–tandem mass spectrometry-based proteomic approach (nano-LC–MS/MS) with subsequent label-free quantification was performed on proteins extracted from cells sampled at different time points during retentostat cultivation. Proteins detected at low (0.002 h−1) and high (0.06 h−1) growth rates were compared between corresponding growth conditions (acetate or acetate plus benzoate). Carbon limitation significantly increased the abundances of several catabolic proteins involved in the degradation of substrates not present in the medium (ethanol, butyrate, fatty acids, and aromatic compounds). Growth rate-specific physiology was reflected in the changed abundances of energy-, chemotaxis-, oxidative stress-, and transport-related proteins. Mimicking natural conditions by extremely slow bacterial growth allowed to show how G. metallireducens optimized its physiology in order to survive in its natural habitats, since it was prepared to consume several carbon sources simultaneously and to withstand various environmental stresses.
    Systematic and Applied Microbiology 06/2014; 37(4). DOI:10.1016/j.syapm.2014.02.005 · 3.28 Impact Factor
  • Source
    • "However, hydrogenase expression in this instance may be an example of this population maximizing energy generation during exposure to relatively carbon rich environmental conditions. In addition, recent studies have suggested a role for hydrogenases as part of the oxidative stress response in Geobacter species [35]. A function in oxidative stress would correlate to the central metabolism carbon flux profiles we infer here, when there is a shift from anabolic to respiratory processes, thus increasing oxidative stress. "
    [Show abstract] [Hide abstract]
    ABSTRACT: While microbial activities in environmental systems play a key role in the utilization and cycling of essential elements and compounds, microbial activity and growth frequently fluctuates in response to environmental stimuli and perturbations. To investigate these fluctuations within a saturated aquifer system, we monitored a carbon-stimulated population while iron reduction was occurring, using 16S rRNA abundances and high-resolution tandem mass spectrometry proteome measurements. Following carbon amendment, 16S rRNA analysis of temporally separated samples revealed the rapid enrichment of -like environmental strains with strong similarity to . Tandem mass spectrometry proteomics measurements suggest high carbon flux through respiratory pathways, and the synthesis of anapleurotic four carbon compounds from acetyl-CoA via pyruvate ferredoxin oxidoreductase activity. Across a 40-day period where Fe(III) reduction was occurring, fluctuations in protein expression reflected changes in anabolic versus catabolic reactions, with increased levels of biosynthesis occurring soon after acetate arrival in the aquifer. In addition, localized shifts in nutrient limitation were inferred based on expression of nitrogenase enzymes and phosphate uptake proteins. These temporal data offer the first example of differing microbial protein expression associated with changing geochemical conditions in a subsurface environment.
    PLoS ONE 03/2013; 8(3):e57819. DOI:10.1371/journal.pone.0057819 · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background The genetic features that facilitate Campylobacter jejuni’s adaptation to a wide range of environments are not completely defined. However, whole genome expression studies showed that respiratory proteins (RPs) were differentially expressed under varying conditions and stresses, suggesting further unidentified roles for RPs in C. jejuni’s adaptation. Therefore, our objectives were to characterize the contributions of selected RPs to C. jejuni’s i- key survival phenotypes under different temperature (37°C vs. 42°C) and oxygen (microaerobic, ambient, and oxygen-limited/anaerobic) conditions and ii- its interactions with intestinal epithelial cells from disparate hosts (human vs. chickens). Results C. jejuni mutant strains with individual deletions that targeted five RPs; nitrate reductase (ΔnapA), nitrite reductase (ΔnrfA), formate dehydrogenase (ΔfdhA), hydrogenase (ΔhydB), and methylmenaquinol:fumarate reductase (ΔmfrA) were used in this study. We show that only the ΔfdhA exhibited a decrease in motility; however, incubation at 42°C significantly reduced the deficiency in the ΔfdhA’s motility as compared to 37°C. Under all tested conditions, the ΔmfrA showed a decreased susceptibility to hydrogen peroxide (H2O2), while the ΔnapA and the ΔfdhA showed significantly increased susceptibility to the oxidant as compared to the wildtype. Further, the susceptibility of the ΔnapA to H2O2 was significantly more pronounced at 37°C. The biofilm formation capability of individual RP mutants varied as compared to the wildtype. However, the impact of the deletion of certain RPs affected biofilm formation in a manner that was dependent on temperature and/or oxygen concentration. For example, the ΔmfrA displayed significantly deficient and increased biofilm formation under microaerobic conditions at 37°C and 42°C, respectively. However, under anaerobic conditions, the ΔmfrA was only significantly impaired in biofilm formation at 42°C. Additionally, the RPs mutants showed differential ability for infecting and surviving in human intestinal cell lines (INT-407) and primary chicken intestinal epithelial cells, respectively. Notably, the ΔfdhA and the ΔhydB were deficient in interacting with both cell types, while the ΔmfrA displayed impairments only in adherence to and invasion of INT-407. Scanning electron microscopy showed that the ΔhydB and the ΔfdhA exhibited filamentous and bulging (almost spherical) cell shapes, respectively, which might be indicative of defects in cell division. Conclusions We conclude that the RPs contribute to C. jejuni’s motility, H2O2 resistance, biofilm formation, and in vitro interactions with hosts’ intestinal cells. Further, the impact of certain RPs varied in response to incubation temperature and/or oxygen concentration. Therefore, RPs may facilitate the prevalence of C. jejuni in a variety of niches, contributing to the pathogen’s remarkable potential for adaptation.
    BMC Microbiology 11/2012; 12(1):258. DOI:10.1186/1471-2180-12-258 · 2.73 Impact Factor
Show more