Spindle- or lemon-shaped viruses infect archaea in diverse environments. Due to the highly pleomorphic nature of these virions, which can be found with cylindrical tails emanating from the ...spindle-shaped body, structural studies of these capsids have been challenging. We have determined the atomic structure of the capsid of Sulfolobus monocaudavirus 1, a virus that infects hosts living in nearly boiling acid. A highly hydrophobic protein, likely integrated into the host membrane before the virions assemble, forms 7 strands that slide past each other in both the tails and the spindle body. We observe the discrete steps that occur as the tail tubes expand, and these are due to highly conserved quasiequivalent interactions with neighboring subunits maintained despite significant diameter changes. Our results show how helical assemblies can vary their diameters, becoming nearly spherical to package a larger genome and suggest how all spindle-shaped viruses have evolved from archaeal rod-like viruses.
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•We present the first atomic structure of an archaeal spindle-shaped virus•Spindle-shaped viruses have evolved from archaeal rod-shaped viruses•Hydrophobic interactions underlie the pleomorphism of spindle-shaped capsids
Structural analysis of an archaea-specific virus reveals principles for how filamentous assemblies of hydrophobic proteins can readily accommodate changes in morphology relevant for virus evolution and potentially for contexts as diverse as eukaryotic membrane dynamics and intermediate filaments.
Abstract Marine bacteriophage PM2 infects gram-negative Pseudoalteromonas species and is currently the only assigned member of the Corticoviridae family. The icosahedral protein shell covers an ...internal protein-rich phage membrane that encloses the highly supercoiled dsDNA genome. In this study we investigated PM2 entry into the host. Our results indicate that PM2 adsorption to the host is dependent on the intracellular ATP concentration, while genome penetration through the cytoplasmic membrane depends on the presence of millimolar concentrations of calcium ions in the medium. In the absence of Ca2+ the infection is arrested at the entry stage but can be rescued by the addition of Ca2+ . Interestingly, PM2 entry induces abrupt cell lysis if the host outer membrane is not stabilized by divalent cations. Experimental data described in this study in combination with results obtained previously allowed us to propose a sequential model describing the entry of bacteriophage PM2 into the host cells.
The evolution of archaeal flagellar filaments Kreutzberger, Mark A B; Cvirkaite-Krupovic, Virginija; Liu, Ying ...
Proceedings of the National Academy of Sciences - PNAS,
07/2023, Letnik:
120, Številka:
28
Journal Article
Recenzirano
Odprti dostop
Flagellar motility has independently arisen three times during evolution: in bacteria, archaea, and eukaryotes. In prokaryotes, the supercoiled flagellar filaments are composed largely of a single ...protein, bacterial or archaeal flagellin, although these two proteins are not homologous, while in eukaryotes, the flagellum contains hundreds of proteins. Archaeal flagellin and archaeal type IV pilin are homologous, but how archaeal flagellar filaments (AFFs) and archaeal type IV pili (AT4Ps) diverged is not understood, in part, due to the paucity of structures for AFFs and AT4Ps. Despite having similar structures, AFFs supercoil, while AT4Ps do not, and supercoiling is essential for the function of AFFs. We used cryo-electron microscopy to determine the atomic structure of two additional AT4Ps and reanalyzed previous structures. We find that all AFFs have a prominent 10-strand packing, while AT4Ps show a striking structural diversity in their subunit packing. A clear distinction between all AFF and all AT4P structures involves the extension of the N-terminal α-helix with polar residues in the AFFs. Additionally, we characterize a flagellar-like AT4P from
with filament and subunit structure similar to that of AFFs which can be viewed as an evolutionary link, showing how the structural diversity of AT4Ps likely allowed for an AT4P to evolve into a supercoiling AFF.
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.
Extracellular vesicles and nanotubes could play a profound role in archaeal physiology, evolution and environmental adaptation by promoting intercellular transfer of viral and cellular nucleic acids and proteins.
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