dChan
Anonymous ID: a0fdae Jan. 30, 2024, 6:44 p.m. No.20332711   ๐Ÿ—„๏ธ.is ๐Ÿ”—kun

>>20332596

https://archive.fo/klBBX

https://www.biorxiv.org/content/10.1101/2024.01.20.576352v1

>Here, we describe the โ€œObelisks,โ€ a previously unrecognised class of viroid-like elements that we first identified in human gut metatranscriptomic data. โ€œObelisksโ€ share several properties: (i) apparently circular RNA โˆผ1kb genome assemblies, (ii) predicted rod-like secondary structures encompassing the entire genome, and (iii) open reading frames coding for a novel protein superfamily, which we call the โ€œOblinsโ€. We find that Obelisks form their own distinct phylogenetic group with no detectable sequence or structural similarity to known biological agents. Further, Obelisks are prevalent in tested human microbiome metatranscriptomes with representatives detected in โˆผ7% of analysed stool metatranscriptomes (29/440) and in โˆผ50% of analysed oral metatranscriptomes (17/32). Obelisk compositions appear to differ between the anatomic sites and are capable of persisting in individuals, with continued presence over >300 days observed in one case. Large scale searches identified 29,959 Obelisks (clustered at 90% nucleotide identity), with examples from all seven continents and in diverse ecological niches. From this search, a subset of Obelisks are identified to code for Obelisk-specific variants of the hammerhead type-III self-cleaving ribozyme. Lastly, we identified one case of a bacterial species (Streptococcus sanguinis) in which a subset of defined laboratory strains harboured a specific Obelisk RNA population. As such, Obelisks comprise a class of diverse RNAs that have colonised, and gone unnoticed in, human, and global microbiomes.