Extracellular membrane vesicles and nanotubes in Archaea.

Junfeng Liu,Patrick Forterre,Virginija Cvirkaite-Krupovic,Mart Krupovic,Aurore Gorlas,Nicolas Soler

doi:10.1093/femsml/uqab007

Abstract

Membrane-bound extracellular vesicles (EVs) are secreted by cells from all three domains of life and their implication in various biological processes is increasingly recognized. In this review, we summarize the current knowledge on archaeal EVs and nanotubes, and emphasize their biological significance. In archaea, the EVs and nanotubes have been largely studied in representative species from the phyla Crenarchaeota and Euryarchaeota. The archaeal EVs have been linked to several physiological processes such as detoxification, biomineralization and transport of biological molecules, including chromosomal, viral or plasmid DNA, thereby taking part in genome evolution and adaptation through horizontal gene transfer. The biological significance of archaeal nanotubes is yet to be demonstrated, although they could participate in EV biogenesis or exchange of cellular contents. We also discuss the biological mechanisms leading to EV/nanotube biogenesis in Archaea. It has been recently demonstrated that, similar to eukaryotes, EV budding in crenarchaea depends on the ESCRT machinery, whereas the mechanism of EV budding in euryarchaeal lineages, which lack the ESCRT-III homologues, remains unknown.

Highlights

Archaea have been recognized as a separate domain of life, besides Bacteria and Eukarya, only in 1977 by Carl Woese and colleagues who compared the ribosomal RNA gene sequences from diverse organisms (Woese and Fox 1977)
A major difference between Archaea and Bacteria that probably influences the respective mechanisms of extracellular vesicles (EVs) and nanotube production is the structure of their cell envelopes
Since the genomes of Thermococcales and of other Euryarchaeota do not encode for endosomal sorting complexes required for transport (ESCRT)-III homologues (Makarova et al 2010), the mechanism of EV production in this phylum is likely to be different from that postulated for Sulfolobales (Liu et al 2021b)

Summary

Introduction

Archaea have been recognized as a separate domain of life, besides Bacteria and Eukarya, only in 1977 by Carl Woese and colleagues who compared the ribosomal RNA (rRNA) gene sequences from diverse organisms (Woese and Fox 1977). Similar to bacteria and eukaryotes, archaeal cells commonly secrete extracellular vesicles (EVs) and some produce tubular structures resembling bacterial nanopods and/or nanotubes (Gill, Catchpole and Forterre 2019). A major difference between Archaea and Bacteria that probably influences the respective mechanisms of EV and nanotube production is the structure of their cell envelopes.

Results

Conclusion