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Updated: Jun 9, 2025
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Human Colonoid Monolayers to Study Interactions Between Pathogens, Commensals, and Host Intestinal Epithelium
Published on: April 9, 2019
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Viroid-like colonists of human microbiomes
Ivan N Zheludev1, Robert C Edgar2, Maria Jose Lopez-Galiano3
1Stanford University, Department of Biochemistry, Stanford, CA, USA.
Cell
|October 31, 2024
Summary
Scientists discovered "obelisks," novel circular RNA elements with unique structures and genes. These prevalent RNA molecules were found in diverse environments, including the human microbiome, suggesting a significant, yet unexplored, biological role.
Area of Science:
- Molecular Biology
- Microbiology
- Genomics
Background:
- Heritable RNA elements represent a poorly understood aspect of molecular biology.
- The diversity and prevalence of non-coding and regulatory RNAs are increasingly recognized.
Purpose of the Study:
- To describe a newly identified class of heritable RNA elements, termed "obelisks."
- To characterize their genomic, structural, and phylogenetic properties.
- To investigate their prevalence in global and human microbiomes.
Main Methods:
- Bioinformatic analysis of RNA sequences and structures.
- Phylogenetic analysis to determine evolutionary relationships.
- Metatranscriptomic data analysis to assess prevalence in various environments.
- Identification of a bacterial host for a specific obelisk.
Main Results:
- Discovery of "obelisks": circular RNA molecules (~1 kb) with predicted rod-like structures and open reading frames encoding Oblin proteins.
- Identification of a subset containing hammerhead ribozymes.
- Obelisks form a distinct phylogenetic group.
- Over 29,000 distinct obelisks identified globally.
- High prevalence in human microbiomes (stool and oral).
- Established Streptococcus sanguinis as a host for an obelisk, with non-essential maintenance for bacterial growth.
Conclusions:
- Obelisks represent a novel, diverse class of heritable RNA elements.
- They have colonized various ecological niches, including the human microbiome, largely unnoticed.
- Further research is needed to determine the functional impact and biological significance of obelisks.
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