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25/07/03/1124254 story

Candidatus Sukunaarchaeum Mirabile is a Novel Archaeon With an Unprecedentedly Small Genome

posted by janrinok on Saturday July 05, @11:43AM   
from the that's-what-she-said dept.

upstart writes:

Candidatus Sukunaarchaeum Mirabile Is A Novel Archaeon With An Unprecedentedly Small Genome:

Defining the minimal genetic requirements for cellular life remains a fundamental question in biology. Genomic exploration continually reveals novel microbial lineages, often exhibiting extreme genome reduction, particularly within symbiotic relationships.

Here, we report the discovery of Candidatus Sukunaarchaeum mirabile, a novel archaeon with an unprecedentedly small genome of only 238 kbp —less than half the size of the smallest previously known archaeal genome— from a dinoflagellate-associated microbial community.

Phylogenetic analyses place Sukunaarchaeum as a deeply branching lineage within the tree of Archaea, representing a novel major branch distinct from established phyla. Environmental sequence data indicate that sequences closely related to Sukunaarchaeum form a diverse and previously overlooked clade in microbial surveys.

Its genome is profoundly stripped-down, lacking virtually all recognizable metabolic pathways, and primarily encoding the machinery for its replicative core: DNA replication, transcription, and translation. This suggests an unprecedented level of metabolic dependence on a host, a condition that challenges the functional distinctions between minimal cellular life and viruses.

The discovery of Sukunaarchaeum pushes the conventional boundaries of cellular life and highlights the vast unexplored biological novelty within microbial interactions, suggesting that further exploration of symbiotic systems may reveal even more extraordinary life forms, reshaping our understanding of cellular evolution.

See also:

• A cellular entity retaining only its replicative core: Hidden archaeal lineage with an ultra-reduced genome
• Is This How Viruses Actually Formed? Groundbreaking Biological Discovery

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Original Submission

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• Is it a protovirus?Is it a protovirus? (Score: 3, Interesting) by khallow on Saturday July 05, @03:25PM (1 child)

  by khallow (3766) on Saturday July 05, @03:25PM (#1409391) Journal

  The YouTube link at the bottom "Is This How Viruses Actually Formed?" is an interesting question (though I haven't watched the video being in a non-video environment). This "archaeon" is stripped down to near virus-level parasitism (it apparently has somewhat more machinery than a typical virus such as its own replication machinery and uses the host cell's resources to completely cover its metabolism needs). It's not a stretch to suppose that some viruses are merely more stripped down versions of archaeons that managed to strip most of that away.
  
  We already know there are weird DNA exchanges going on between microbes and viruses. This organism could even be a case of a virus way back when that went the other way and accidentally borrows something from its host to become an archaeon. I doubt it though because the host cell in this case appears to be an eukaryote (dinoflagellate). I can't see how a virus could incorporate cellular processes eukaryote without developing some of the advanced structures of the host cell like nucleus and organelles.
  
  Also one would need to explain why there are both DNA and RNA viruses. That seems significantly different modes of infection?

  • Re:Is it a protovirus?(Score: 3, Interesting) by c0lo on Saturday July 05, @10:54PM

    by c0lo (156) on Saturday July 05, @10:54PM (#1409408) Journal

    the situation is way more complex than chicken-and-egg [wikipedia.org]

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    https://www.youtube.com/@ProfSteveKeen https://soylentnews.org/~MichaelDavidCrawford

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