scholarly journals The Archaellum of Methanospirillum hungatei is Electrically Conductive

2018 ◽  
Author(s):  
David J.F. Walker ◽  
Eric Martz ◽  
Dawn E. Holmes ◽  
Zimu Zhou ◽  
Stephen S. Nonnenmann ◽  
...  
Keyword(s):  
Electron Transport ◽  
Long Range ◽  
Electrically Conductive ◽  
Methanospirillum Hungatei

Here we report that the archaellum of Methanospirillum hungatei is electrically conductive. Our analysis of the previously published archaellum structure suggests that a core of tightly packed phenylalanines is one likely route for electron conductance. This is the first demonstration that electrically conductive protein filaments (e-PFs) have evolved in Archaea and is the first e-PF for which a structure is known, facilitating mechanistic evaluation of long-range electron transport in e-PFs.

scholarly journals Protein Nanowires: the Electrification of the Microbial World and Maybe Our Own

2020 ◽  
Vol 202 (20) ◽  
Author(s):  
Derek R. Lovley ◽  
Dawn E. Holmes
Keyword(s):  
Electron Transport ◽  
Long Range ◽  
Electronic Devices ◽  
Electricity Production ◽  
Microbial World ◽  
Electrically Conductive ◽  
Anaerobic Digesters ◽  
Content Type ◽  
Type Iv ◽  
Type Iv Pilin

ABSTRACT Electrically conductive protein nanowires appear to be widespread in the microbial world and are a revolutionary “green” material for the fabrication of electronic devices. Electrically conductive pili (e-pili) assembled from type IV pilin monomers have independently evolved multiple times in microbial history as have electrically conductive archaella (e-archaella) assembled from homologous archaellin monomers. A role for e-pili in long-range (micrometer) extracellular electron transport has been demonstrated in some microbes. The surprising finding of e-pili in syntrophic bacteria and the role of e-pili as conduits for direct interspecies electron transfer have necessitated a reassessment of routes for electron flux in important methanogenic environments, such as anaerobic digesters and terrestrial wetlands. Pilin monomers similar to those found in e-pili may also be a major building block of the conductive “cables” that transport electrons over centimeter distances through continuous filaments of cable bacteria consisting of a thousand cells or more. Protein nanowires harvested from microbes have many functional and sustainability advantages over traditional nanowire materials and have already yielded novel electronic devices for sustainable electricity production, neuromorphic memory, and sensing. e-pili can be mass produced with an Escherichia coli chassis, providing a ready source of material for electronics as well as for studies on the basic mechanisms for long-range electron transport along protein nanowires. Continued exploration is required to better understand the electrification of microbial communities with microbial nanowires and to expand the “green toolbox” of sustainable materials for wiring and powering the emerging “Internet of things.”

Long-range electron transport to Fe(III) oxide via pili with metallic-like conductivity

2012 ◽  
Vol 40 (6) ◽  
pp. 1186-1190 ◽  
Author(s):  
Derek R. Lovley
Keyword(s):  
Electron Transport ◽  
Long Range ◽  
Geobacter Sulfurreducens ◽  
Oxide Reduction ◽  
Electron Hopping ◽  
Electrically Conductive ◽  
Electron Conduction ◽  
Geobacter Species ◽  
Redox Active

The mechanisms for Fe(III) oxide reduction by Geobacter species are of interest because Geobacter species have been shown to play an important role in Fe(III) oxide reduction in a diversity of environments in which Fe(III) reduction is a geochemically significant process. Geobacter species specifically express pili during growth on Fe(III) oxide compared with growth on soluble chelated Fe(III), and mutants that cannot produce pili are unable to effectively reduce Fe(III) oxide. The pili of Geobacter sulfurreducens are electrically conductive along their length under physiologically relevant conditions and exhibit a metallic-like conductivity similar to that observed previously in synthetic organic metals. Metallic-like conductivity in a biological protein filament is a previously unrecognized mechanism for electron transport that differs significantly from the more well-known biological strategy of electron hopping/tunnelling between closely spaced redox-active proteins. The multihaem c-type cytochrome OmcS is specifically associated with pili and is necessary for Fe(III) oxide reduction. However, multiple lines of evidence, including the metallic-like conductivity of the pili and the fact that OmcS molecules are spaced too far apart for electron hopping/tunnelling, indicate that OmcS is not responsible for long-range electron conduction along the pili. The role of OmcS may be to facilitate electron transfer from the pili to Fe(III) oxide. Long-range electron transport via pili with metallic-like conductivity is a paradigm shift that has important implications not only for Fe(III) oxide reduction, but also for interspecies electron exchange in syntrophic microbial communities as well as microbe–electrode interactions and the emerging field of bioelectronics.

scholarly journals Structure of a cytochrome-based bacterial nanowire

2018 ◽  
Author(s):  
David J. Filman ◽  
Stephen F. Marino ◽  
Joy E. Ward ◽  
Lu Yang ◽  
Zoltán Mester ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Transport ◽  
Long Range ◽  
Biological Significance ◽  
New Materials ◽  
Electrically Conductive ◽  
Cryo Electron Microscopy ◽  
Novel Structure ◽  
Bacterial Nanowires

AbstractElectrically conductive pili from Geobacter species, termed bacterial “nanowires”, are intensely studied for their biological significance and potential in the development of new materials. We have characterized a unique nanowire from conductive G. sulfurreducens pili preparations by cryo-electron microscopy composed solely of the c-type cytochrome OmcS. We present here, at 3.4 Å resolution, a novel structure of a cytochrome-based filament and discuss its possible role in long-range biological electron transport.Summary sentenceCryo-electron microscopy reveals the remarkable assembly of a c-type cytochrome into filaments comprising a heme-based bacterial nanowire.

scholarly journals Direct Observation of Electrically Conductive Pili Emanating from Geobacter sulfurreducens

2021 ◽  
Author(s):  
Xinying Liu ◽  
David Jeffrey Fraser Walker ◽  
Stephen Nonnenmann ◽  
Dezhi Sun ◽  
Derek R. Lovley
Keyword(s):  
Electron Transfer ◽  
Electron Transport ◽  
Long Range ◽  
Geobacter Sulfurreducens ◽  
Metal Corrosion ◽  
Extracellular Electron Transfer ◽  
Wild Type ◽  
Electrically Conductive ◽  
In The Wild ◽  
Pilin Gene

Geobacter sulfurreducens is a model microbe for elucidating the mechanisms for extracellular electron transfer in several biogeochemical cycles, bioelectrochemical applications, and microbial metal corrosion. Multiple lines of evidence previously suggested that electrically conductive pili (e-pili) are an essential conduit for long-range extracellular electron transport in G. sulfurreducens. However, it has recently been reported that G. sulfurreducens does not express e-pili and that filaments comprised of multi-heme c-type cytochromes are responsible for long-range electron transport. This possibility was directly investigated by examining cells, rather than filament preparations, with atomic force microscopy. Approximately 90 % of the filaments emanating from wild-type cells had a diameter (3 nm) and conductance consistent with previous reports of e-pili harvested from G. sulfurreducens or heterologously expressed in E. coli from the G. sulfurreducens pilin gene. The remaining 10% of filaments had a morphology consistent with filaments comprised of the c-type cytochrome OmcS. A strain expressing a modified pilin gene designed to yield poorly conductive pili expressed 90 % filaments with a 3 nm diameter, but greatly reduced conductance, further indicating that the 3 nm diameter conductive filaments in the wild-type strain were e-pili. A strain in which genes for five of the most abundant outer-surface c-type cytochromes, including OmcS, was deleted yielded only 3 nm diameter filaments with the same conductance as in the wild-type. These results demonstrate that e-pili are the most abundant conductive filaments expressed by G. sulfurreducens, consistent with previous functional studies demonstrating the need for e-pili for long-range extracellular electron transfer.

scholarly journals Direct Observation of Electrically Conductive Pili Emanating from Geobacter sulfurreducens

mBio ◽  
2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Xinying Liu ◽  
David J. F. Walker ◽  
Stephen S. Nonnenmann ◽  
Dezhi Sun ◽  
Derek R. Lovley
Keyword(s):  
Electron Transport ◽  
Environmental Impacts ◽  
Long Range ◽  
Direct Observation ◽  
Geobacter Sulfurreducens ◽  
Electrically Conductive ◽  
Metal Cofactors

Electroactive microbes have significant environmental impacts, as well as applications in bioenergy and bioremediation. The composition, function, and even existence of electrically conductive pili (e-pili) has been one of the most contentious areas of investigation in electromicrobiology, in part because e-pili offer a mechanism for long-range electron transport that does not involve the metal cofactors common in much of biological electron transport.

scholarly journals Cytochrome OmcS is not essential for long-range electron transport in Geobacter sulfurreducens strain KN400

2020 ◽  
Author(s):  
David J. F. Walker ◽  
Yang Li ◽  
David Meier ◽  
Samantha Pinches ◽  
Dawn E. Holmes ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electron Transport ◽  
Long Range ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer ◽  
Electrically Conductive ◽  
Closely Related Species ◽  
Direct Interspecies Electron Transfer ◽  
Interspecies Electron Transfer ◽  
Extracellular Electron Transport

AbstractThe multi-heme c-type cytochrome OmcS, is one of the central components for extracellular electron transport in Geobacter sulfurreducens strain DL-1, but its role in other microbes, including other strains of G. sulfurreducens is currently a matter of debate. Therefore, we investigated the function of OmcS in G. sulfurreducens strain KN400, which is even more effective in extracellular electron transfer than strain DL-1. We found that deleting omcS from strain KN400 did not negatively impact the rate of Fe(III) oxide reduction and did not affect the strain’s ability to accept electrons via direct interspecies electron transfer. The OmcS-deficient strain also continued to produce conductive filaments, consistent with the concept that electrically conductive pili are the primary conduit for long-range electron transfer in G. sulfurreducens and closely related species. These findings, coupled with the lack of OmcS homologs in most other microbes capable of extracellular electron transfer, suggest that OmcS is not a common critical component for extracellular electron transfer.

scholarly journals Efficient long-range conduction in cable bacteria through nickel protein wires

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Henricus T. S. Boschker ◽  
Perran L. M. Cook ◽  
Lubos Polerecky ◽  
Raghavendran Thiruvallur Eachambadi ◽  
Helena Lozano ◽  
...  
Keyword(s):  
Electron Transport ◽  
Long Range ◽  
Cell Envelope ◽  
Protein Structures ◽  
Chemical Imaging ◽  
Electrical Currents ◽  
Core Proteins ◽  
Active Metal ◽  
Unknown Form ◽  
High Resolution Microscopy

AbstractFilamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.

Electron Transport in the Long-Range Charge-Recombination Dynamics of Single Encapsulated Dye Molecules on TiO2Nanoparticle Films

2009 ◽  
Vol 121 (40) ◽  
pp. 7515-7518 ◽  
Author(s):  
Xiangyang Wu ◽  
Toby D. M. Bell ◽  
Edwin K. L. Yeow
Keyword(s):  
Electron Transport ◽  
Long Range ◽  
Charge Recombination ◽  
Dye Molecules ◽  
Recombination Dynamics

Long-range correlated electron transport in M-DNA

2016 ◽  
Vol 478 ◽  
pp. 45-47
Author(s):  
Aleš Omerzu ◽  
Miloš Borovšak
Keyword(s):  
Electron Transport ◽  
Long Range ◽  
Correlated Electron

scholarly journals Plastocyanin is the long-range electron carrier between photosystem II and photosystem I in plants

2020 ◽  
Vol 117 (26) ◽  
pp. 15354-15362 ◽  
Author(s):  
Ricarda Höhner ◽  
Mathias Pribil ◽  
Miroslava Herbstová ◽  
Laura Susanna Lopez ◽  
Hans-Henning Kunz ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Long Range ◽  
Narrow Range ◽  
Higher Plants ◽  
Regulatory Element ◽  
Photosynthetic Electron Transport ◽  
Electron Carrier ◽  
Mobile Electron ◽  
Electron Carriers

In photosynthetic electron transport, large multiprotein complexes are connected by small diffusible electron carriers, the mobility of which is challenged by macromolecular crowding. For thylakoid membranes of higher plants, a long-standing question has been which of the two mobile electron carriers, plastoquinone or plastocyanin, mediates electron transport from stacked grana thylakoids where photosystem II (PSII) is localized to distant unstacked regions of the thylakoids that harbor PSI. Here, we confirm that plastocyanin is the long-range electron carrier by employing mutants with different grana diameters. Furthermore, our results explain why higher plants have a narrow range of grana diameters since a larger diffusion distance for plastocyanin would jeopardize the efficiency of electron transport. In the light of recent findings that the lumen of thylakoids, which forms the diffusion space of plastocyanin, undergoes dynamic swelling/shrinkage, this study demonstrates that plastocyanin diffusion is a crucial regulatory element of plant photosynthetic electron transport.

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