Abstract: The archaellum is the macromolecular machinery that Archaea use for propulsion or surface adhesion, enabling them to proliferate and invade new territories. The molecular composition of the archaellum and of the motor that drives it appears to be entirely distinct from that of the functionally equivalent bacterial flagellum and flagellar motor. Yet, the structure of the archaellum machinery is scarcely known. Using combined modes of electron cryo-microscopy (cryoEM), we have solved the structure of the Pyrococcus furiosus archaellum filament at 4.2 Å resolution and visualise the architecture and organisation of its motor complex in situ. This allows us to build a structural model combining the archaellum and its motor complex, paving the way to a molecular understanding of archaeal swimming motion. (public access) – Bertram Daum, Janet Vonck Annett Bellack Paushali Chaudhury Robert Reichelt Sonja-Verena Albers Reinhard Rachel Werner Kühlbrandt, “Structure and in situ organisation of the Pyrococcus furiosus archaellum machinery”[color emphasis added]
This isn’t good news for the oft-heard claim that “all life arose from a single cell,” which Carl Woese, who identified the Archaea, doubted.
See also: Convergent evolution: Speciation in butterflies an unusually tough mess
Marsupial wallabies do have placentas and milk that does similar functions
and
Evolution appears to converge on goals—but in Darwinian terms, is that possible?
Archaellum:
Flagellum:
Hat tip: Pos-Darwinista