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Frontiers in Microbiology 2015The bacterial proteins of the Dsb family-important components of the post-translational protein modification system-catalyze the formation of disulfide bridges, a... (Review)
Review
The bacterial proteins of the Dsb family-important components of the post-translational protein modification system-catalyze the formation of disulfide bridges, a process that is crucial for protein structure stabilization and activity. Dsb systems play an essential role in the assembly of many virulence factors. Recent rapid advances in global analysis of bacteria have thrown light on the enormous diversity among bacterial Dsb systems. While the Escherichia coli disulfide bond-forming system is quite well understood, the mechanisms of action of Dsb systems in other bacteria, including members of class Epsilonproteobacteria that contain pathogenic and non-pathogenic bacteria colonizing extremely diverse ecological niches, are poorly characterized. Here we present a review of current knowledge on Epsilonproteobacteria Dsb systems. We have focused on the Dsb systems of Campylobacter spp. and Helicobacter spp. because our knowledge about Dsb proteins of Wolinella and Arcobacter spp. is still scarce and comes mainly from bioinformatic studies. Helicobacter pylori is a common human pathogen that colonizes the gastric epithelium of humans with severe consequences. Campylobacter spp. is a leading cause of zoonotic enteric bacterial infections in most developed and developing nations. We focus on various aspects of the diversity of the Dsb systems and their influence on pathogenicity, particularly because Dsb proteins are considered as potential targets for a new class of anti-virulence drugs to treat human infections by Campylobacter or Helicobacter spp.
PubMed: 26106374
DOI: 10.3389/fmicb.2015.00570 -
Journal of Biological Inorganic... Feb 2022Since the characterization of cytochrome c as a multiheme nitrite reductase, research on this enzyme has gained major interest. Today, it is known as pentaheme... (Review)
Review
Since the characterization of cytochrome c as a multiheme nitrite reductase, research on this enzyme has gained major interest. Today, it is known as pentaheme cytochrome c nitrite reductase (NrfA). Part of the NH produced from NO is released as NH leading to nitrogen loss, similar to denitrification which generates NO, NO, and N. NH can also be used for assimilatory purposes, thus NrfA contributes to nitrogen retention. It catalyses the six-electron reduction of NO to NH, hosting four His/His ligated c-type hemes for electron transfer and one structurally differentiated active site heme. Catalysis occurs at the distal side of a Fe(III) heme c proximally coordinated by lysine of a unique CXXCK motif (Sulfurospirillum deleyianum, Wolinella succinogenes) or, presumably, by the canonical histidine in Campylobacter jejeuni. Replacement of Lys by His in NrfA of W. succinogenes led to a significant loss of enzyme activity. NrfA forms homodimers as shown by high resolution X-ray crystallography, and there exist at least two distinct electron transfer systems to the enzyme. In γ-proteobacteria (Escherichia coli) NrfA is linked to the menaquinol pool in the cytoplasmic membrane through a pentaheme electron carrier (NrfB), in δ- and ε-proteobacteria (S. deleyianum, W. succinogenes), the NrfA dimer interacts with a tetraheme cytochrome c (NrfH). Both form a membrane-associated respiratory complex on the extracellular side of the cytoplasmic membrane to optimize electron transfer efficiency. This minireview traces important steps in understanding the nature of pentaheme cytochrome c nitrite reductases, and discusses their structural and functional features.
Topics: Ammonia; Ferric Compounds; Nitrite Reductases; Nitrites; Wolinella
PubMed: 34865208
DOI: 10.1007/s00775-021-01921-4 -
FEBS Letters Nov 2003The three-dimensional structure of Wolinella succinogenes quinol:fumarate reductase (QFR), a dihaem-containing member of the superfamily of succinate:quinone... (Comparative Study)
Comparative Study Review
The three-dimensional structure of Wolinella succinogenes quinol:fumarate reductase (QFR), a dihaem-containing member of the superfamily of succinate:quinone oxidoreductases (SQOR), has been determined at 2.2 A resolution by X-ray crystallography [Lancaster et al., Nature 402 (1999) 377-385]. The structure and mechanism of W. succinogenes QFR and their relevance to the SQOR superfamily have recently been reviewed [Lancaster, Adv. Protein Chem. 63 (2003) 131-149]. Here, a comparison is presented of W. succinogenes QFR to the recently determined structure of the mono-haem containing succinate:quinone reductase from Escherichia coli [Yankovskaya et al., Science 299 (2003) 700-704]. In spite of differences in polypeptide and haem composition, the overall topology of the membrane anchors and their relative orientation to the conserved hydrophilic subunits is strikingly similar. A major difference is the lack of any evidence for a 'proximal' quinone site, close to the hydrophilic subunits, in W. succinogenes QFR.
Topics: Amino Acid Sequence; Binding Sites; Crystallography, X-Ray; Electron Transport; Electron Transport Complex II; Escherichia coli; Evolution, Molecular; Heme; Models, Molecular; Molecular Sequence Data; Oxidoreductases; Protein Conformation; Protein Subunits; Proton-Motive Force; Sequence Homology, Amino Acid; Wolinella
PubMed: 14630313
DOI: 10.1016/s0014-5793(03)01100-1 -
Biochimica Et Biophysica Acta Jan 2002The epsilon-proteobacteria form a subdivision of the Proteobacteria including the genera Wolinella, Campylobacter, Helicobacter, Sulfurospirillum, Arcobacter and... (Comparative Study)
Comparative Study Review
The epsilon-proteobacteria form a subdivision of the Proteobacteria including the genera Wolinella, Campylobacter, Helicobacter, Sulfurospirillum, Arcobacter and Dehalospirillum. The majority of these bacteria are oxidase-positive microaerophiles indicating an electron transport chain with molecular oxygen as terminal electron acceptor. However, numerous members of the epsilon-proteobacteria also grow in the absence of oxygen. The common presence of menaquinone and fumarate reduction activity suggests anaerobic fumarate respiration which was demonstrated for the rumen bacterium Wolinella succinogenes as well as for Sulfurospirillum deleyianum, Campylobacter fetus, Campylobacter rectus and Dehalospirillum multivorans. To date, complete genome sequences of Helicobacter pylori and Campylobacter jejuni are available. These bacteria and W. succinogenes contain the genes frdC, A and B encoding highly similar heterotrimeric enzyme complexes belonging to the family of succinate:quinone oxidoreductases. The crystal structure of the W. succinogenes quinol:fumarate reductase complex (FrdCAB) was solved recently, thus providing a model of succinate:quinone oxidoreductases from epsilon-proteobacteria. Succinate:quinone oxidoreductases are being discussed as possible therapeutic targets in the treatment of several pathogenic epsilon-proteobacteria.
Topics: Citric Acid Cycle; Electron Transport; Electron Transport Complex II; Energy Metabolism; Fumarates; Models, Chemical; Models, Molecular; Multienzyme Complexes; Operon; Oxidation-Reduction; Oxidoreductases; Proteobacteria; Succinate Dehydrogenase; Succinic Acid; Wolinella
PubMed: 11803019
DOI: 10.1016/s0005-2728(01)00230-4 -
Biochimica Et Biophysica Acta Jun 2009Recent phylogenetic analyses have established that the Epsilonproteobacteria form a globally ubiquitous group of ecologically significant organisms that comprises a... (Review)
Review
Recent phylogenetic analyses have established that the Epsilonproteobacteria form a globally ubiquitous group of ecologically significant organisms that comprises a diverse range of free-living bacteria as well as host-associated organisms like Wolinella succinogenes and pathogenic Campylobacter and Helicobacter species. Many Epsilonproteobacteria reduce nitrate and nitrite and perform either respiratory nitrate ammonification or denitrification. The inventory of epsilonproteobacterial genomes from 21 different species was analysed with respect to key enzymes involved in respiratory nitrogen metabolism. Most ammonifying Epsilonproteobacteria employ two enzymic electron transport systems named Nap (periplasmic nitrate reductase) and Nrf (periplasmic cytochrome c nitrite reductase). The current knowledge on the architecture and function of the corresponding proton motive force-generating respiratory chains using low-potential electron donors are reviewed in this article and the role of membrane-bound quinone/quinol-reactive proteins (NapH and NrfH) that are representative of widespread bacterial electron transport modules is highlighted. Notably, all Epsilonproteobacteria lack a napC gene in their nap gene clusters. Possible roles of the Nap and Nrf systems in anabolism and nitrosative stress defence are also discussed. Free-living denitrifying Epsilonproteobacteria lack the Nrf system but encode cytochrome cd(1) nitrite reductase, at least one nitric oxide reductase and a characteristic cytochrome c nitrous oxide reductase system (cNosZ). Interestingly, cNosZ is also found in some ammonifying Epsilonproteobacteria and enables nitrous oxide respiration in W. succinogenes.
Topics: Bacterial Proteins; Campylobacter jejuni; Cytochromes a1; Cytochromes c1; Electron Transport; Energy Metabolism; Epsilonproteobacteria; Genes, Bacterial; Models, Biological; Multigene Family; Nitrate Reductase; Nitrate Reductases; Nitrogen; Nitrous Oxide; Oxidation-Reduction; Periplasm; Quaternary Ammonium Compounds; Wolinella
PubMed: 19171117
DOI: 10.1016/j.bbabio.2008.12.010 -
Biochimica Et Biophysica Acta Oct 2002The structure of the respiratory membrane protein complex quinol:fumarate reductase (QFR) from Wolinella succinogenes has been determined by X-ray crystallography at... (Review)
Review
The structure of the respiratory membrane protein complex quinol:fumarate reductase (QFR) from Wolinella succinogenes has been determined by X-ray crystallography at 2.2-A resolution [Nature 402 (1999) 377]. Based on the structure of the three protein subunits A, B, and C and the arrangement of the six prosthetic groups (a covalently bound FAD, three iron-sulfur clusters, and two haem b groups), a pathway of electron transfer from the quinol-oxidising dihaem cytochrome b in the membrane to the site of fumarate reduction in the hydrophilic subunit A has been proposed. The structure of the membrane-integral dihaem cytochrome b reveals that all transmembrane helical segments are tilted with respect to the membrane normal. The "four-helix" dihaem binding motif is very different from other dihaem-binding transmembrane four-helix bundles, such as the "two-helix motif" of the cytochrome bc(1) complex and the "three-helix motif" of the formate dehydrogenase/hydrogenase group. The gamma-hydroxyl group of Ser C141 has an important role in stabilising a kink in transmembrane helix IV. By combining the results from site-directed mutagenesis, functional and electrochemical characterisation, and X-ray crystallography, a residue was identified which was found to be essential for menaquinol oxidation [Proc. Natl. Acad. Sci. U. S. A. 97 (2000) 13051]. The distal location of this residue in the structure indicates that the coupling of the oxidation of menaquinol to the reduction of fumarate in dihaem-containing succinate:quinone oxidoreductases could in principle be associated with the generation of a transmembrane electrochemical potential. However, it is suggested here that in W. succinogenes QFR, this electrogenic effect is counterbalanced by the transfer of two protons via a proton transfer pathway (the "E-pathway") in concert with the transfer of two electrons via the membrane-bound haem groups. According to this "E-pathway hypothesis", the net reaction catalysed by W. succinogenes QFR does not contribute directly to the generation of a transmembrane electrochemical potential.
Topics: Binding Sites; Crystallization; Crystallography, X-Ray; Cytochrome b Group; Electron Transport; Electron Transport Complex IV; Intracellular Membranes; Membrane Proteins; Models, Chemical; Models, Molecular; Molecular Structure; Oxidoreductases; Protein Conformation; Vitamin K 2; Wolinella
PubMed: 12409197
DOI: 10.1016/s0005-2736(02)00571-0 -
Biochimica Et Biophysica Acta.... Jan 2019Reduction of sulfite to sulfide is an essential step in the biogeochemical sulfur cycle. The Epsilonproteobacterium Wolinella succinogenes uses the copper-containing...
Reduction of sulfite to sulfide is an essential step in the biogeochemical sulfur cycle. The Epsilonproteobacterium Wolinella succinogenes uses the copper-containing octahaem cytochrome c sulfite reductase MccA to respire sulfite. MccA is encoded by the first gene of the mcc gene cluster, whose transcription is apparently induced by the two-component regulatory system MccRS. It has been proposed that the iron‑sulfur protein MccC, the putative quinol dehydrogenase MccD, the copper chaperone MccL as well as menaquinone-6 (MK) and/or 8-methylmenaquinone-6 (8-MMK) are involved in the electron transport chain of W. succinogenes sulfite respiration. Here, non-polar W. succinogenes mutants were constructed that lacked MccC, MccD, MccL or the 8-MMK-producing MK methyltransferase MqnK. Each mutant possessed a frameshift-corrected mccR gene, thus inducing mcc expression in the presence of a mixture of fumarate and sulfite as terminal electron acceptors. Under these conditions, growth by sulfite respiration of cells lacking MccA, MccC or MccD was found to be abolished. However, cells lacking MccL or 8-MMK still coupled formate oxidation to sulfite reduction and grew by sulfite respiration to some extent. The results indicate that MccR, MccC, MccD, MccL and 8-MMK are essential or significant components of W. succinogenes sulfite respiration.
Topics: Cell Respiration; Electron Transport; Electron Transport Chain Complex Proteins; Fumarates; Genes, MCC; Multigene Family; Mutant Proteins; Oxidation-Reduction; Sulfite Dehydrogenase; Sulfites; Wolinella
PubMed: 30342041
DOI: 10.1016/j.bbabio.2018.10.002 -
Microbiology (Reading, England) Aug 2014Global warming is moving more and more into the public consciousness. Besides the commonly mentioned carbon dioxide and methane, nitrous oxide (N2O) is a powerful...
Global warming is moving more and more into the public consciousness. Besides the commonly mentioned carbon dioxide and methane, nitrous oxide (N2O) is a powerful greenhouse gas in addition to its contribution to depletion of stratospheric ozone. The increasing concern about N2O emission has focused interest on underlying microbial energy-converting processes and organisms harbouring N2O reductase (NosZ), such as denitrifiers and ammonifiers of nitrate and nitrite. Here, the epsilonproteobacterial model organism Wolinella succinogenes is investigated with regard to its capacity to produce and consume N2O during growth by anaerobic nitrate ammonification. This organism synthesizes an unconventional cytochrome c nitrous oxide reductase (cNosZ), which is encoded by the first gene of an atypical nos gene cluster. However, W. succinogenes lacks a nitric oxide (NO)-producing nitrite reductase of the NirS- or NirK-type as well as an NO reductase of the Nor-type. Using a robotized incubation system, the wild-type strain and suitable mutants of W. succinogenes that either produced or lacked cNosZ were analysed as to their production of NO, N2O and N2 in both nitrate-sufficient and nitrate-limited growth medium using formate as electron donor. It was found that cells growing in nitrate-sufficient medium produced small amounts of N2O, which derived from nitrite and, most likely, from the presence of NO. Furthermore, cells employing cNosZ were able to reduce N2O to N2. This reaction, which was fully inhibited by acetylene, was also observed after adding N2O to the culture headspace. The results indicate that W. succinogenes cells are competent in N2O and N2 production despite being correctly grouped as respiratory nitrate ammonifiers. N2O production is assumed to result from NO detoxification and nitrosative stress defence, while N2O serves as a terminal electron acceptor in anaerobic respiration. The ecological implications of these findings are discussed.
Topics: Ammonium Compounds; Bacterial Proteins; Nitrates; Nitrous Oxide; Oxidoreductases; Wolinella
PubMed: 24781903
DOI: 10.1099/mic.0.079293-0 -
Frontiers in Microbiology 2019The Campylobacterota, previously known as Epsilonproteobacteria, are a large group of Gram-negative mainly, spiral-shaped motile bacteria. Some members like the spp.... (Review)
Review
The Campylobacterota, previously known as Epsilonproteobacteria, are a large group of Gram-negative mainly, spiral-shaped motile bacteria. Some members like the spp. are free-living, while others such as spp. can only persist in strict association with a host organism as commensal or as pathogen. Species of this phylum colonize diverse habitats ranging from deep-sea thermal vents to the human stomach wall. Despite their divergent environments, they share common energy conservation mechanisms. The Campylobacterota have a large and remarkable repertoire of electron transport chain enzymes, given their small genomes. Although members of recognized families of transcriptional regulators are found in these genomes, sofar no orthologs known to be important for energy or redox metabolism such as ArcA, FNR or NarP are encoded in the genomes of the Campylobacterota. In this review, we discuss the strategies that members of Campylobacterota utilize to conserve energy and the corresponding regulatory mechanisms that regulate the branched electron transport chains in these bacteria.
PubMed: 31417516
DOI: 10.3389/fmicb.2019.01719 -
Proceedings of the National Academy of... Sep 2003To understand the origin and emergence of pathogenic bacteria, knowledge of the genetic inventory from their nonpathogenic relatives is a prerequisite. Therefore, the...
To understand the origin and emergence of pathogenic bacteria, knowledge of the genetic inventory from their nonpathogenic relatives is a prerequisite. Therefore, the 2.11-megabase genome sequence of Wolinella succinogenes, which is closely related to the pathogenic bacteria Helicobacter pylori and Campylobacter jejuni, was determined. Despite being considered nonpathogenic to its bovine host, W. succinogenes holds an extensive repertoire of genes homologous to known bacterial virulence factors. Many of these genes have been acquired by lateral gene transfer, because part of the virulence plasmid pVir and an N-linked glycosylation gene cluster were found to be syntenic between C. jejuni and genomic islands of W. succinogenes. In contrast to other host-adapted bacteria, W. succinogenes does harbor the highest density of bacterial sensor kinases found in any bacterial genome to date, together with an elaborate signaling circuitry of the GGDEF family of proteins. Because the analysis of the W. succinogenes genome also revealed genes related to soil- and plant-associated bacteria such as the nif genes, W. succinogenes may represent a member of the epsilon proteobacteria with a life cycle outside its host.
Topics: Bacterial Proteins; Genome, Bacterial; Glycosylation; Molecular Sequence Data; Open Reading Frames; Phylogeny; Signal Transduction; Virulence; Wolinella
PubMed: 14500908
DOI: 10.1073/pnas.1932838100