Role of individual nap gene cluster products in NapC-independent nitrate respiration of Wolinella succinogenes

Kern, Melanie; Mager., A.; Simon, Jörg

doi:10.1099/mic.0.2007/009928-0

Cited by 35 publications

(69 citation statements)

References 40 publications

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“…The inclusion of napGH differentiates this cluster from the nap-␣ cluster and makes it more similar in organization to nap-␤ clusters from gammaproteobacteria, including several Shewanella species and E. coli (43). NapGH likely form a quinol dehydrogenase and may transfer electrons to NapBA (20). In many bacteria, this Nap supports anaerobic growth via nitrate respiration (14).…”

Section: Resultsmentioning

confidence: 99%

Physiological Roles for Two Periplasmic Nitrate Reductases in Rhodobacter sphaeroides 2.4.3 (ATCC 17025)

Hartsock

Shapleigh

2011

Journal of Bacteriology

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The metabolically versatile purple bacterium Rhodobacter sphaeroides 2.4.3 is a denitrifier whose genome contains two periplasmic nitrate reductase-encoding gene clusters. This work demonstrates nonredundant physiological roles for these two enzymes. One cluster is expressed aerobically and repressed under low oxygen while the second is maximally expressed under low oxygen. Insertional inactivation of the aerobically expressed nitrate reductase eliminated aerobic nitrate reduction, but cells of this strain could still respire nitrate anaerobically. In contrast, when the anaerobic nitrate reductase was absent, aerobic nitrate reduction was detectable, but anaerobic nitrate reduction was impaired. The aerobic nitrate reductase was expressed but not utilized in liquid culture but was utilized during growth on solid medium. Growth on a variety of carbon sources, with the exception of malate, the most oxidized substrate used, resulted in nitrite production on solid medium. This is consistent with a role for the aerobic nitrate reductase in redox homeostasis. These results show that one of the nitrate reductases is specific for respiration and denitrification while the other likely plays a role in redox homeostasis during aerobic growth.Nitrate reduction is widespread among bacteria, where it is used for both assimilatory and dissimilatory processes (14, 37). Assimilatory nitrate reduction produces nitrite, which is further reduced to ammonia and incorporated into cell biomass. Dissimilatory processes include denitrification, the respiration of nitrate to nitrogen gas, and ammonification, i.e., the respiration of nitrate to ammonia. These varied uses for nitrate make its reduction an important reaction in the global nitrogen cycle (5). The use of chemically fixed sources of nitrogen as fertilizer has led to nitrate being a common cause of eutrophication, increasing the significance of nitrate reduction in global biogeochemical cycles (5). Understanding the regulation and physiological roles of nitrate reductases in diverse organisms will allow more accurate modeling and predictions of nitrate fate in the environment.There is one type of assimilatory nitrate reductase, known as Nas, but there are two dissimilatory types, referred to as Nar and Nap. Nas is cytoplasmic, Nar is membrane bound, and Nap is localized to the periplasm (37). Environmental surveys for the dissimilatory Nap-and Nar-type genes demonstrate an almost equal representation of both groups (4). Many bacteria with Nap have NapABC as the functional core, where NapA is the catalytic subunit and NapB and NapC are heme-containing subunits involved in electron transfer (14). NapA has a molybdenum cofactor as the site of nitrate reduction. NapA and NapB form a periplasmic complex while NapC is membrane associated to mediate electron transfer from quinol to NapAB. While Nap turnover is not directly associated with generation of a proton motive force (PMF), electron flow through NADH dehydrogenase along with the further reduction steps, as in denitrification, w...

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Section: Resultsmentioning

confidence: 99%

Physiological Roles for Two Periplasmic Nitrate Reductases in Rhodobacter sphaeroides 2.4.3 (ATCC 17025)

Hartsock

Shapleigh

2011

Journal of Bacteriology

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“…The mode of action of PceT resembles that of other chaperones involved in the maturation of Tat-dependent proteins such as TorD (Genest et al, 2009;Sargent, 2007b), DmsD (Guymer et al, 2009;Li et al, 2010) or NapD proteins (Kern et al, 2007;Maillard et al, 2007;Potter & Cole, 1999). Although belonging to very distinct protein families, these chaperones specifically recognize the signal peptide of their cognate Tat-dependent protein and participate in their maturation process.…”

Section: Dedicated Chaperone Function Of Dha-pcetmentioning

confidence: 99%

Redundancy and specificity of multiple trigger factor chaperones in Desulfitobacteria

2011

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The ribosome-bound trigger factor (TF) chaperone assists folding of newly synthesized polypeptides and participates in the assembly of macromolecular complexes. In the present study we showed that multiple distinct TF paralogues are present in genomes of Desulfitobacteria, a bacterial genus known for its ability to grow using organohalide respiration. Two full-length TF chaperones and at least one truncated TF (lacking the N-terminal ribosome-binding domain) were identified, the latter being systematically linked to clusters of reductive dehalogenase genes encoding the key enzymes in organohalide respiration. Using a well-characterized heterologous chaperone-deficient Escherichia coli strain lacking both TF and DnaK chaperones, we demonstrated that all three TF chaperones were functional in vivo, as judged by their ability to partially suppress bacterial growth defects and protein aggregation in the absence of both major E. coli chaperones. Next, we found that the N-terminal truncated TF-like protein PceT functions as a dedicated chaperone for the cognate reductive dehalogenase PceA by solubilizing and stabilizing it in the heterologous system. Finally, we showed that PceT specifically interacts with the twin-arginine signal peptide of PceA. Taken together, our data define PceT (and more generally the new RdhT family) as a class of TF-like chaperones involved in the maturation of proteins secreted by the twin-arginine translocation pathway. INTRODUCTIONFolding of newly synthesized polypeptides in the cytosol is assisted by molecular chaperones (Hartl & Hayer-Hartl, 2009). In bacteria, the ribosome-bound chaperone trigger factor (TF) plays a major role in this process. In Escherichia coli, it is believed that most nascent polypeptides emerging from the ribosome interact with TF before completing their folding (Hoffmann et al., 2010;Kramer et al., 2009). TF chaperone specifically binds to L23 protein at the polypeptide exit tunnel of active ribosomes with a 1 : 1 stoichiometry (Ferbitz et al., 2004;Kramer et al., 2002b;Patzelt et al., 2001). Remarkably, it has been recently shown that TF cycles the ribosome on and off and that ribosome-free TF may stay bound to elongating polypeptides for a prolonged period (Kaiser et al., 2006;Rutkowska et al., 2008).In agreement with such a property, it has recently been proposed that TF participates in the post-translational assembly of large protein complexes in the cytosol (Martinez-Hackert & Hendrickson, 2009). The TF chaperone is composed of three distinct protein domains, which have been functionally and structurally determined. The Nterminal domain (NTD) consists of a ribosome-binding domain containing a conserved motif responsible for binding to ribosomal proteins (Hesterkamp et al., 1997;Kramer et al., 2002aKramer et al., , 2004. The central module in the TF structure corresponds to the C-terminal domain (CTD) and harbours the core of the chaperone activity (Genevaux et al., 2004;Kramer et al., 2004). Finally the domain encoded at the centre of the tig gene exhibits a ...

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“…The napDAB genes encode the molybdopterin-containing reductase (NapA), the diheme component of the periplasmic electron transfer system (NapB, the redox partner of NapA) and a putative chaperone involved in the maturation of NapA (NapD). In Epsilonproteobacteria, the role of individual products of the nap gene cluster has been investigated in W. succinogenes (Kern et al, 2007). Consistent with the lack of the NapC (Simon et al, 2003), the electron transfer to NapAB in W. succinogenes is mediated by the NapGH membrane-bound ironsulfur periplasmic quinone dehydrogenase complex (Kern and Simon, 2008).…”

Section: Introductionmentioning

confidence: 92%

“…SB155 and Nitratiruptur salsuginis (Figure 1a). The nitrate reduction pathway in C. mediatlanticus was reconstructed from its genome sequence and a model based on the gene functions assigned to W. succinogenes (Kern et al, 2007) Detection and phylogenetic analysis of the NapA periplasmic nitrate reductase in reference strains of vent Epsilonproteobacteria Phylogenetic analysis of the amino acid sequence deduced from the napA genes placed the enzymes of all the Epsilonproteobacteria in a group distinct from the gammaproteobacterial NapA (Figure 2a). Three major clusters were identified: one of these clusters comprised sequences from the Nautiliales, which includes the genera Caminibacter and Nautilia, all isolated from deep-sea hydrothermal vents (Figure 2a).…”

Section: Reconstruction Of the Nap Gene Cluster And Of The Nitrate Rementioning

confidence: 99%

“…NapL is an iron-sulfur periplasmic protein present in all epsilonproteobacterial genomes. Although the function of NapL and NapF is currently unclear, recent data indicate that in W. succinogenes the NapGHF complex is involved in menaquinol oxidation, electron transfer to periplasmic NapA and maturation of the cytoplasmic NapA precursor (Kern et al, 2007;Kern and Simon, 2009b).…”

Section: Introductionmentioning

confidence: 99%

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Deep-sea hydrothermal ventEpsilonproteobacteriaencode a conserved and widespread nitrate reduction pathway (Nap)

et al. 2014

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Despite the frequent isolation of nitrate-respiring Epsilonproteobacteria from deep-sea hydrothermal vents, the genes coding for the nitrate reduction pathway in these organisms have not been investigated in depth. In this study we have shown that the gene cluster coding for the periplasmic nitrate reductase complex (nap) is highly conserved in chemolithoautotrophic, nitrate-reducing Epsilonproteobacteria from deep-sea hydrothermal vents. Furthermore, we have shown that the napA gene is expressed in pure cultures of vent Epsilonproteobacteria and it is highly conserved in microbial communities collected from deep-sea vents characterized by different temperature and redox regimes. The diversity of nitrate-reducing Epsilonproteobacteria was found to be higher in moderate temperature, diffuse flow vents than in high temperature black smokers or in low temperatures, substrate-associated communities. As NapA has a high affinity for nitrate compared with the membrane-bound enzyme, its occurrence in vent Epsilonproteobacteria may represent an adaptation of these organisms to the low nitrate concentrations typically found in vent fluids. Taken together, our findings indicate that nitrate reduction is widespread in vent Epsilonproteobacteria and provide insight on alternative energy metabolism in vent microorganisms. The occurrence of the nap cluster in vent, commensal and pathogenic Epsilonproteobacteria suggests that the ability of these bacteria to respire nitrate is important in habitats as different as the deep-sea vents and the human body.

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Role of individual nap gene cluster products in NapC-independent nitrate respiration of Wolinella succinogenes

Cited by 35 publications

References 40 publications

Physiological Roles for Two Periplasmic Nitrate Reductases in Rhodobacter sphaeroides 2.4.3 (ATCC 17025)

Physiological Roles for Two Periplasmic Nitrate Reductases in Rhodobacter sphaeroides 2.4.3 (ATCC 17025)

Redundancy and specificity of multiple trigger factor chaperones in Desulfitobacteria

Deep-sea hydrothermal ventEpsilonproteobacteriaencode a conserved and widespread nitrate reduction pathway (Nap)

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