Search bioRxiv⌕ Search

bioRxiv · 10.1101/458356

The Archaellum of Methanospirillum hungatei is Electrically Conductive

Abstract

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.

Source connections

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Walker, D. J. F., Martz, E., Holmes, D. E., Zhou, Z., Nonnenmann, S. S., Lovley, D. R.. 2018-10-31. The Archaellum of Methanospirillum hungatei is Electrically Conductive. https://doi.org/10.1101/458356

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

A closed genome of Streptococcus agalactiae ST347/II reveals a composite integrative element coupling nisin P biosynthesis to erm(B) and tet(O) in Dominican group B Streptococcus

Clindamycin is the alternative for intrapartum prophylaxis against group B Streptococcus in penicillin-allergic women, and whether it works depends on which lineages carry the resistance and on the mobile element that moves it. No Dominican group B Streptococcus genome has been closed. A Streptococcus agalactiae isolate from residual diagnostic material was sequenced twice on Oxford Nanopore, annotated, and screened against 83 genomes from a published Dominican maternal colonisation survey. The assembly is one circular chromosome of 2,066,859 bp with all seven rRNA operons resolved: ST347/CC19, serotype II, carrying erm(B), tet(O), mef(J) and msr(I). Two integrative conjugative elements were delimited: one of ~34 kb related to Tn5252 carrying erm(B) and tet(O), another of ~35 kb at a tRNA-Lys gene carrying mef(J) and msr(I). An eleven-gene class I lanthipeptide cluster lies 96 bp from the first element, on the same strand and with no annotated feature between them; its precursor encodes a 31-residue core identical to nisin P. The complete operon was found in 12 of the 83 genomes, 13 of 84 (15.5%) with the isolate. tet(O) was present in all 12 carriers and none of the 71 others (Fisher p = 1.03 x 10^-14), erm(B) in 12 of 12 against 3 of 71 (p = 4.70 x 10^-12). All eleven ST1 genomes lack both the operon and the nisin resistance protein; all 15 ST1010/IV genomes carry aac(6')-Ie/aph(2'')-Ia. Clindamycin resistance is therefore tightly associated with a lantibiotic-encoding element and contiguous with it in the one closed genome; in the drafts the relationship is statistical, and co-occurrence is not linkage. The ST1 absence predicts lineage-wide susceptibility, testable by deferred antagonism.

microbiology↗

Factors affecting microbial community composition in Split Lake, MB, Canada

Split Lake is a large freshwater lake in northern Manitoba, Canada, that receives major inflows from the Nelson River, Burntwood River, and Grassy River. In 1976, during the Churchill River Diversion (CRD) project, most of the water in the Churchill River was diverted into the Nelson River via the Rat River, and the Burntwood River, creating a large inflow pressure in the lower Nelson area, including Split Lake. Decades after its implementation, the Churchill River Diversion still influences ecological and environmental processes in the area. In this study, metabarcoding of the 16S rRNA gene was employed to characterize the microbial community structure of the lake. Environmental factors (temperature, pH, turbidity, dissolved oxygen) and cyanotoxin levels were also assessed. The objectives of this study were to establish a baseline for microbiota across the lake and examine how environmental variables affect microbial population dynamics. The study was conducted in the summer of 2024, encompassing 14 sites on Split Lake and 2 sites on Assean Lake, an adjacent waterbody with minimal influence from hydroelectric infrastructure. Split Lake was found to harbor six distinct microbial clusters, with turbidity and dissolved oxygen levels correlating with different aquatic regimes within the lake. The predominant taxa in Split Lake included Actinobacteria hgcI clade and Cyanobium. Microcystin concentrations measured throughout the study were always below the Maximum Acceptable Concentration (MAC) set for Canadian federal drinking water standards.

microbiology↗

Particle-Associated Prokaryotic Community Structures in the Bering and Chukchi Seas

Free-living and particle-associated bacteria play distinct roles in the cycling of organic matter, but how these lifestyles are partitioned in the highly productive, rapidly warming Bering and Chukchi Seas is largely unknown. During the Arctic Shelf Growth, Advection, Respiration and Deposition Rate Experiments (ASGARD) cruise in June 2017, a period of anomalously warm sea surface temperatures, we collected 78 samples at three depths (surface, middle, and bottom) at 12 process stations and sequentially filtered them onto 20 {micro}m, 3 {micro}m, and 0.2 {micro}m filters. Using 16S rRNA gene amplicon sequencing and hierarchical clustering of amplicon sequence variant (ASV) relative abundances, we resolved four sample clusters. Although pore size was not used to build the clusters, communities separated into a free-living cluster associated mainly with Anadyr Water (FL1; 0.2 {micro}m fraction) and three particle-associated clusters (PA1-PA3; 3 and 20 {micro}m fractions), several of which were enriched in Bacteroidia. Alphaproteobacteria, Gammaproteobacteria, and Bacteroidia were present in all size fractions, with Gammaproteobacteria most biased toward the free-living fraction. Community structure did not differ with depth, consistent with the shallow, weakly stratified shelf, and distance-based redundancy analysis identified salinity as the sole significant environmental factor distinguishing communities. These results suggest that lifestyle and water-mass origin, rather than depth, structure size-fractionated bacterial communities on the Pacific Arctic shelf, and that freshening and changes in bloom dynamics could reshape particle-associated communities in this region.

microbiology↗