@article {3058,
	title = {Direct Observation of Electrically Conductive Pili Emanating from .},
	journal = {mBio},
	volume = {12},
	year = {2021},
	month = {2021 Aug 31},
	pages = {e0220921},
	abstract = {<p>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 -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 Escherichia coli from the G. sulfurreducens pilin gene. The remaining 10\% of filaments had a morphology consistent with filaments comprised of the -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 -type cytochromes, including OmcS, were 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.  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. This study demonstrates that e-pili are abundant filaments emanating from Geobacter sulfurreducens, which serves as a model for long-range extracellular electron transfer in direct interspecies electron transfer, dissimilatory metal reduction, microbe-electrode exchange, and corrosion caused by direct electron uptake from Fe(0). The methods described in this study provide a simple strategy for evaluating the distribution of conductive filaments throughout the microbial world with an approach that avoids artifactual production and/or enrichment of filaments that may not be physiologically relevant.</p>},
	keywords = {Electric Conductivity, Electrons, Escherichia coli, Fimbriae Proteins, Fimbriae, Bacterial, Geobacter, Microscopy, Atomic Force, Oxidation-Reduction},
	issn = {2150-7511},
	doi = {10.1128/mBio.02209-21},
	author = {Liu, Xinying and Walker, David J F and Nonnenmann, Stephen S and Sun, Dezhi and Lovley, Derek R}
}
@article {3075,
	title = {Decorating the Outer Surface of Microbially Produced Protein Nanowires with Peptides.},
	journal = {ACS Synth Biol},
	volume = {8},
	year = {2019},
	month = {2019 Aug 16},
	pages = {1809-1817},
	abstract = {<p>The potential applications of electrically conductive protein nanowires (e-PNs) harvested from  might be greatly expanded if the outer surface of the wires could be modified to confer novel sensing capabilities or to enhance binding to other materials. We developed a simple strategy for functionalizing e-PNs with surface-exposed peptides. The  gene for the monomer that assembles into e-PNs was modified to add peptide tags at the carboxyl terminus of the monomer. Strains of  were constructed that fabricated synthetic e-PNs with a six-histidine "His-tag" or both the His-tag and a nine-peptide "HA-tag" exposed on the outer surface. Addition of the peptide tags did not diminish e-PN conductivity. The abundance of HA-tag in e-PNs was controlled by placing expression of the gene for the synthetic monomer with the HA-tag under transcriptional regulation. These studies suggest broad possibilities for tailoring e-PN properties for diverse applications.</p>},
	keywords = {Carboxy-Lyases, Ethylene Glycols, Molecular Structure, Nanowires, Oxygenases, Peptides, Phenylalanine Ammonia-Lyase, Plasmids, Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Styrenes},
	issn = {2161-5063},
	doi = {10.1021/acssynbio.9b00131},
	author = {Ueki, Toshiyuki and Walker, David J F and Tremblay, Pier-Luc and Nevin, Kelly P and Ward, Joy E and Woodard, Trevor L and Nonnenmann, Stephen S and Lovley, Derek R}
}
