The membrane-bound tetrahaem c-type cytochrome CymA interacts directly with the soluble fumarate reductase in Shewanella

2002 ◽  
Vol 30 (4) ◽  
pp. 658-662 ◽  
Author(s):  
C. Schwalb ◽  
S. K. Chapman ◽  
G. A. Reid
Keyword(s):  
Electron Transfer ◽  
Outer Membrane ◽  
Shewanella Oneidensis ◽  
Anaerobic Respiration ◽  
Fumarate Reductase ◽  
Sulphur Compounds ◽  
Sequence Alignments ◽  
Membrane Bound ◽  
Periplasmic Domain

Shewanella spp. demonstrate great variability in the use of terminal electron acceptors in anaerobic respiration; these include nitrate, fumarate, DMSO, trimethylamine oxide, sulphur compounds and metal oxides. These pathways open up possible applications in bioremediation. The wide variety of respiratory substrates for Shewanella is correlated with the evolution of several multi-haem membrane-bound, periplasmic and outer-membrane c-type cytochromes. The 21 kDa c-type cytochrome CymA of the freshwater strain Shewanella oneidensis MR-1 has an N-terminal membrane anchor and a globular tetrahaem periplasmic domain. According to sequence alignments, CymA is a member of the NapC/NirT family. This family of redox proteins is responsible for electron transfer from the quinone pool to periplasmic and outer-membrane-bound reductases. Prior investigations have shown that the absence of CymA results in loss of the ability to respire with Fe(III), fumarate and nitrate, indicating that CymA is involved in electron transfer to several terminal reductases. Here we describe the expression, purification and characterization of a soluble, truncated CymA (‘CymA). Potentiometric studies suggest that there are two pairs of haems with potentials of -175 and -261 mV and that ‘CymA is an efficient electron donor for the soluble fumarate reductase, flavocytochrome c3.

scholarly journals Mind the gap: diversity and reactivity relationships among multihaem cytochromes of the MtrA/DmsE family

2012 ◽  
Vol 40 (6) ◽  
pp. 1268-1273 ◽  
Author(s):  
Kathryn D. Bewley ◽  
Mackenzie A. Firer-Sherwood ◽  
Jee-Young Mock ◽  
Nozomi Ando ◽  
Catherine L. Drennan ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Evolutionary Relationship ◽  
Shewanella Oneidensis ◽  
Anaerobic Respiration ◽  
Electron Acceptors ◽  
Protein Film ◽  
Protein Film Voltammetry

Shewanella oneidensis MR-1 has the ability to use many external terminal electron acceptors during anaerobic respiration, such as DMSO. The pathway that facilitates this electron transfer includes the decahaem cytochrome DmsE, a paralogue of the MtrA family of decahaem cytochromes. Although both DmsE and MtrA are decahaem cytochromes implicated in the long-range electron transfer across a ~300 Å (1 Å=0.1 nm) wide periplasmic ‘gap’, MtrA has been shown to be only 105 Å in maximal length. In the present paper, DmsE is further characterized via protein film voltammetry, revealing that the electrochemistry of the DmsE haem cofactors display macroscopic potentials lower than those of MtrA by 100 mV. It is possible this tuning of the redox potential of DmsE is required to shuttle electrons to the outer-membrane proteins specific to DMSO reduction. Other decahaem cytochromes found in S. oneidensis, such as the outer-membrane proteins MtrC, MtrF and OmcA, have been shown to have electrochemical properties similar to those of MtrA, yet possess a different evolutionary relationship.

scholarly journals Periplasmic Electron Transfer via the c-Type Cytochromes MtrA and FccA of Shewanella oneidensis MR-1

2009 ◽  
Vol 75 (24) ◽  
pp. 7789-7796 ◽  
Author(s):  
Bjoern Schuetz ◽  
Marcus Schicklberger ◽  
Johannes Kuermann ◽  
Alfred M. Spormann ◽  
Johannes Gescher
Keyword(s):  
Electron Transfer ◽  
Cytoplasmic Membrane ◽  
Shewanella Oneidensis ◽  
Microbial Reduction ◽  
Fumarate Reductase ◽  
Mineral Phase ◽  
Membrane Bound ◽  
Growth Experiments

ABSTRACT Dissimilatory microbial reduction of insoluble Fe(III) oxides is a geochemically and ecologically important process which involves the transfer of cellular, respiratory electrons from the cytoplasmic membrane to insoluble, extracellular, mineral-phase electron acceptors. In this paper evidence is provided for the function of the periplasmic fumarate reductase FccA and the decaheme c-type cytochrome MtrA in periplasmic electron transfer reactions in the gammaproteobacterium Shewanella oneidensis. Both proteins are abundant in the periplasm of ferric citrate-reducing S. oneidensis cells. In vitro fumarate reductase FccA and c-type cytochrome MtrA were reduced by the cytoplasmic membrane-bound protein CymA. Electron transfer between CymA and MtrA was 1.4-fold faster than the CymA-catalyzed reduction of FccA. Further experiments showing a bidirectional electron transfer between FccA and MtrA provided evidence for an electron transfer network in the periplasmic space of S. oneidensis. Hence, FccA could function in both the electron transport to fumarate and via MtrA to mineral-phase Fe(III). Growth experiments with a ΔfccA deletion mutant suggest a role of FccA as a transient electron storage protein.

scholarly journals A Hybrid Extracellular Electron Transfer Pathway Enhances the Survival of Vibrio natriegens

2020 ◽  
Vol 86 (19) ◽  
Author(s):  
Bridget E. Conley ◽  
Matthew T. Weinstock ◽  
Daniel R. Bond ◽  
Jeffrey A. Gralnick
Keyword(s):  
Electron Transfer ◽  
Shewanella Oneidensis ◽  
Anaerobic Respiration ◽  
Basic Research ◽  
Extracellular Electron Transfer ◽  
Content Type ◽  
Electron Transfer Pathway ◽  
Sedimentary Environments ◽  
Genetic Potential ◽  
Iron And Manganese

ABSTRACT Vibrio natriegens is the fastest-growing microorganism discovered to date, making it a useful model for biotechnology and basic research. While it is recognized for its rapid aerobic metabolism, less is known about anaerobic adaptations in V. natriegens or how the organism survives when oxygen is limited. Here, we describe and characterize extracellular electron transfer (EET) in V. natriegens, a metabolism that requires movement of electrons across protective cellular barriers to reach the extracellular space. V. natriegens performs extracellular electron transfer under fermentative conditions with gluconate, glucosamine, and pyruvate. We characterized a pathway in V. natriegens that requires CymA, PdsA, and MtrCAB for Fe(III) citrate and Fe(III) oxide reduction, which represents a hybrid of strategies previously discovered in Shewanella and Aeromonas. Expression of these V. natriegens genes functionally complemented Shewanella oneidensis mutants. Phylogenetic analysis of the inner membrane quinol dehydrogenases CymA and NapC in gammaproteobacteria suggests that CymA from Shewanella diverged from Vibrionaceae CymA and NapC. Analysis of sequenced Vibrionaceae revealed that the genetic potential to perform EET is conserved in some members of the Harveyi and Vulnificus clades but is more variable in other clades. We provide evidence that EET enhances anaerobic survival of V. natriegens, which may be the primary physiological function for EET in Vibrionaceae. IMPORTANCE Bacteria from the genus Vibrio occupy a variety of marine and brackish niches with fluctuating nutrient and energy sources. When oxygen is limited, fermentation or alternative respiration pathways must be used to conserve energy. In sedimentary environments, insoluble oxide minerals (primarily iron and manganese) are able to serve as electron acceptors for anaerobic respiration by microorganisms capable of extracellular electron transfer, a metabolism that enables the use of these insoluble substrates. Here, we identify the mechanism for extracellular electron transfer in Vibrio natriegens, which uses a combination of strategies previously identified in Shewanella and Aeromonas. We show that extracellular electron transfer enhanced survival of V. natriegens under fermentative conditions, which may be a generalized strategy among Vibrio spp. predicted to have this metabolism.

scholarly journals Involvement of a Membrane-Bound Class III Adenylate Cyclase in Regulation of Anaerobic Respiration in Shewanella oneidensis MR-1

2009 ◽  
Vol 191 (13) ◽  
pp. 4298-4306 ◽  
Author(s):  
M. A. Charania ◽  
K. L. Brockman ◽  
Y. Zhang ◽  
A. Banerjee ◽  
G. E. Pinchuk ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Shewanella Oneidensis ◽  
Anaerobic Respiration ◽  
Receptor Protein ◽  
Plasmid Replication ◽  
Chromosomal Deletion ◽  
Class Iii ◽  
Membrane Bound ◽  
Flagellum Biosynthesis ◽  
Class Iv

ABSTRACT Unlike other bacteria that use FNR to regulate anaerobic respiration, Shewanella oneidensis MR-1 uses the cyclic AMP receptor protein (CRP) for this purpose. Three putative genes, cyaA, cyaB, and cyaC, predicted to encode class I, class IV, and class III adenylate cyclases, respectively, have been identified in the genome sequence of this bacterium. Functional validation through complementation of an Escherichia coli cya mutant confirmed that these genes encode proteins with adenylate cyclase activities. Chromosomal deletion of either cyaA or cyaB did not affect anaerobic respiration with fumarate, dimethyl sulfoxide (DMSO), or Fe(III), whereas deletion of cyaC caused deficiencies in respiration with DMSO and Fe(III) and, to a lesser extent, with fumarate. A phenotype similar to that of a crp mutant, which lacks the ability to grow anaerobically with DMSO, fumarate, and Fe(III), was obtained when both cyaA and cyaC were deleted. Microarray analysis of gene expression in the crp and cyaC mutants revealed the involvement of both genes in the regulation of key respiratory pathways, such as DMSO, fumarate, and Fe(III) reduction. Additionally, several genes associated with plasmid replication, flagellum biosynthesis, and electron transport were differentially expressed in the cyaC mutant but not in the crp mutant. Our results indicated that CyaC plays a major role in regulating anaerobic respiration and may contribute to additional signaling pathways independent of CRP.

scholarly journals Specific Bonds between an Iron Oxide Surface and Outer Membrane Cytochromes MtrC and OmcA from Shewanella oneidensis MR-1

2007 ◽  
Vol 189 (13) ◽  
pp. 4944-4952 ◽  
Author(s):  
Brian H. Lower ◽  
Liang Shi ◽  
Ruchirej Yongsunthon ◽  
Timothy C. Droubay ◽  
David E. McCready ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Outer Membrane ◽  
Shewanella Oneidensis ◽  
Anaerobic Respiration ◽  
Oxide Surface ◽  
Whole Cell ◽  
Force Microscopy ◽  
Atomic Force ◽  
Pure Protein ◽  
Direct Binding

ABSTRACT Shewanella oneidensis MR-1 is purported to express outer membrane cytochromes (e.g., MtrC and OmcA) that transfer electrons directly to Fe(III) in a mineral during anaerobic respiration. A prerequisite for this type of reaction would be the formation of a stable bond between a cytochrome and an iron oxide surface. Atomic force microscopy (AFM) was used to detect whether a specific bond forms between a hematite (Fe2O3) thin film, created with oxygen plasma-assisted molecular beam epitaxy, and recombinant MtrC or OmcA molecules coupled to gold substrates. Force spectra displayed a unique force signature indicative of a specific bond between each cytochrome and the hematite surface. The strength of the OmcA-hematite bond was approximately twice that of the MtrC-hematite bond, but direct binding to hematite was twice as favorable for MtrC. Reversible folding/unfolding reactions were observed for mechanically denatured MtrC molecules bound to hematite. The force measurements for the hematite-cytochrome pairs were compared to spectra collected for an iron oxide and S. oneidensis under anaerobic conditions. There is a strong correlation between the whole-cell and pure-protein force spectra, suggesting that the unique binding attributes of each cytochrome complement one another and allow both MtrC and OmcA to play a prominent role in the transfer of electrons to Fe(III) in minerals. Finally, by comparing the magnitudes of binding force for the whole-cell versus pure-protein data, we were able to estimate that a single bacterium of S. oneidensis (2 by 0.5 μm) expresses ∼104 cytochromes on its outer surface.

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