Electron tunneling properties of outer-membrane decaheme cytochromes from Shewanella oneidensis

Wigginton, Nicholas S.; Rosso, Kevin M.; Lower, Brian H.; Shi, Liang; Hochella, Michael F.

doi:10.1016/j.gca.2006.10.002

Cited by 58 publications

(66 citation statements)

References 89 publications

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“…As the measurements were carried out in an interfacial setting without bulk water surrounding the cytochromes, lower l values than those found for haem-to-haem ET in solvated MtrF (0.75-1.13 eV; §4.1.2) are indeed to be expected. In contrast to MtrC, tunnelling conductance of OmcA shows no deviation from a smooth exponential tunnelling profile [150,151]. This suggests that the two cytochromes have different ET properties, and thus different roles on the OM of Shewanella, consistent with the functional differences established in other experiments ( §2).…”

Section: Tunnelling Spectroscopysupporting

confidence: 85%

Multi-haem cytochromes inShewanella oneidensisMR-1: structures, functions and opportunities

Breuer

Rosso

Blumberger

et al. 2015

J. R. Soc. Interface.

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219

186

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Multi-haem cytochromes are employed by a range of microorganisms to transport electrons over distances of up to tens of nanometres. Perhaps the most spectacular utilization of these proteins is in the reduction of extracellular solid substrates, including electrodes and insoluble mineral oxides of Fe(III) and Mn(III/IV), by species of Shewanella and Geobacter. However, multihaem cytochromes are found in numerous and phylogenetically diverse prokaryotes where they participate in electron transfer and redox catalysis that contributes to biogeochemical cycling of N, S and Fe on the global scale. These properties of multi-haem cytochromes have attracted much interest and contributed to advances in bioenergy applications and bioremediation of contaminated soils. Looking forward, there are opportunities to engage multi-haem cytochromes for biological photovoltaic cells, microbial electrosynthesis and developing bespoke molecular devices. As a consequence, it is timely to review our present understanding of these proteins and we do this here with a focus on the multitude of functionally diverse multi-haem cytochromes in Shewanella oneidensis MR-1. We draw on findings from experimental and computational approaches which ideally complement each other in the study of these systems: computational methods can interpret experimentally determined properties in terms of molecular structure to cast light on the relation between structure and function. We show how this synergy has contributed to our understanding of multi-haem cytochromes and can be expected to continue to do so for greater insight into natural processes and their informed exploitation in biotechnologies.

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Section: Tunnelling Spectroscopysupporting

confidence: 85%

Multi-haem cytochromes inShewanella oneidensisMR-1: structures, functions and opportunities

Breuer

Rosso

Blumberger

et al. 2015

J. R. Soc. Interface.

Self Cite

219

186

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“…S5). Although possible explanations are speculative at this point, we think that the high currents observed in experiments are due to the involvement of redox states inaccessible under solution conditions without external bias, as discussed earlier in Wigginton et al (16,34).…”

Section: Discussionmentioning

confidence: 54%

Electron flow in multiheme bacterial cytochromes is a balancing act between heme electronic interaction and redox potentials

Breuer

Rosso

Blumberger

2014

Proc. Natl. Acad. Sci. U.S.A.

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173

189

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The naturally widespread process of electron transfer from metal reducing bacteria to extracellular solid metal oxides entails unique biomolecular machinery optimized for long-range electron transport. To perform this function efficiently, microorganisms have adapted multiheme c-type cytochromes to arrange heme cofactors into wires that cooperatively span the cellular envelope, transmitting electrons along distances greater than 100 Å. Implications and opportunities for bionanotechnological device design are selfevident. However, at the molecular level, how these proteins shuttle electrons along their heme wires, navigating intraprotein intersections and interprotein interfaces efficiently, remains a mystery thus far inaccessible to experiment. To shed light on this critical topic, we carried out extensive quantum mechanics/molecular mechanics simulations to calculate stepwise heme-to-heme electron transfer rates in the recently crystallized outer membrane deca-heme cytochrome MtrF. By solving a master equation for electron hopping, we estimate an intrinsic, maximum possible electron flux through solvated MtrF of 10 4 -10 5 s −1 , consistent with recently measured rates for the related multiheme protein complex MtrCAB. Intriguingly, our calculations show that the rapid electron transport through MtrF is the result of a clear correlation between heme redox potential and the strength of electronic coupling along the wire: thermodynamically uphill steps occur only between electronically well-connected stacked heme pairs. This observation suggests that the protein evolved to harbor low-potential hemes without slowing down electron flow. These findings are particularly profound in light of the apparently well-conserved staggered cross-heme wire structural motif in functionally related outer membrane proteins.respiration | density functional theory

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“…To determine whether they reduced Cr(VI), recombinant MtrC and OmcA were purified by following procedures described previously (22,24,32). Briefly, recombinant MtrC and OmcA were overexpressed in S. oneidensis MR-1 cells.…”

Section: Methodsmentioning

confidence: 99%

Extracellular Reduction of Hexavalent Chromium by Cytochromes MtrC and OmcA of Shewanella oneidensis MR-1

Belchik

Kennedy

Dohnálková

et al. 2011

Appl Environ Microbiol

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145

149

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Electron tunneling properties of outer-membrane decaheme cytochromes from Shewanella oneidensis

Cited by 58 publications

References 89 publications

Multi-haem cytochromes inShewanella oneidensisMR-1: structures, functions and opportunities

Multi-haem cytochromes inShewanella oneidensisMR-1: structures, functions and opportunities

Electron flow in multiheme bacterial cytochromes is a balancing act between heme electronic interaction and redox potentials

Extracellular Reduction of Hexavalent Chromium by Cytochromes MtrC and OmcA of Shewanella oneidensis MR-1

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