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Archaea vs. bacteria: Convergent evolution of molecular propeller

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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


Evolution appears to converge on goals—but in Darwinian terms, is that possible?



Hat tip: Pos-Darwinista

"...Archaea have developed their own locomotion machinery called the archaellum, which is distinct from bacterial and eukaryotic flagella in terms of molecular composition and mode of action (Albers and Jarrell, 2015)." "The presence of this blueprint in Archaea and Bacteria also raises the intriguing hypothesis that a common A/T-like progenitor protein and filament existed in the last universal common ancestor (LUCA), before these two domains of life diverged more than 3 billion years ago (Makarova et al., 2016; Weiss et al., 2016)." "The evolutionary reason for the higher complexity of both, bacterial T4P assembly machines as well as flagellar motors is speculative." Structure and in situ organisation of the Pyrococcus furiosus archaellum machinery Bertram Daum, Janet Vonck, Annett Bellack, Paushali Chaudhury, Robert Reichelt, Sonja-Verena Albers, Reinhard Rachel, Werner Kühlbrandt eLife 2017;6:e27470 doi: 10.7554/eLife.27470 Cinderella's story makes more sense: a pumpkin became a carriage, mice turned onto beautiful horses, a cricket was hired as a cochero. :) Dionisio

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