by: Andrei Enrico San Diego (Harbinger)
When hearing the word obelisk, the first thing that pops into mind are the monolithic stone pillars that are set up as monuments or landmarks, but in the field of genetics, an obelisk is something much smaller. In recent research, an obelisk is a class of heritable RNA elements that are characterized by the following features: circular RNA genomes that are approximately 1 kilobase in length, rod-like genome-wide secondary structures, and open reading frames that code a novel protein superfamily called “Oblin.” To put it simply, obelisks are made of circular RNA genomes and their unique rod-shaped structures, which are reminiscent of the ancient pillars. Obelisk has been referred to as “viroid-like” due to its similar characteristics with viroids. However, what sets them both apart is that a viroid does not have the ability to code for proteins. Additionally, unlike standard viruses, obelisks do not encode protein shells or have protective shells made of protein. Instead, they carry RNA instructions in tiny loops.
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The obelisk was discovered when researchers began analyzing genetic libraries and found patterns that did not line up with organisms; this discovery was led by the Nobel Prize winner in Medicine Andrew Fire from Stanford University. Researchers also found out that obelisks were found in human gut and oral bacteria. The technique used to discover the obelisk was called whole metagenome sequencing. It was used to analyze the genetic material from mouth and gut bacteria samples, allowing scientists to read and compare DNA sequences and providing a comprehensive overview of the microbial landscape.
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As stated earlier, the obelisk can encode a protein superfamily. Specifically, two novel proteins, which are Oblin-1 and Oblin-2. Oblin-1 contains motifs that have the ability to bind to divalent metal ions. This is significant because some essential cellular processes require metal ions. On the other hand, Oblin-2 is predicted to have a leucine zipper-like domain, which is a shape often found in transcription factors or proteins that bind to DNA. Furthermore, since obelisks are found in significant numbers in the human microbiome suggests that they might have a potential role in influencing our health and even affect our digestion and immune system responses.
Obelisks may hold promising potential applications in genetics and molecular biology. Since obelisks are newly discovered, they can be used as a novel model for RNA biology and replication mechanisms. Their ability to encode unique proteins and fold into rod-shaped structures challenges our previous understanding of RNA complexity. Our knowledge of genetic diversity is enhanced by this revelation, which could also have significant implications for future studies.
SOURCES
Flores, R., & Owens, R. (2008). Viroids. In Elsevier eBooks (pp. 332–342). https://doi.org/10.1016/b978-012374410-4.00532-x
Freer, C. (2025, April). Obelisk RNAs and oblins as novel oral therapeutic platforms. ResearchGate. https://www.researchgate.net/publication/391271763_Obelisk_RNAs_and_Oblins_as_Novel_Oral_Therapeutic_Platforms
Joseph, J. (2024, December 21). New forms of life discovered inside human bodies. Earth.com. https://www.earth.com/news/scientists-find-new-forms-of-life-inside-humans-rna-carriers-obelisks/
Zheludev, I. N., Edgar, R. C., Lopez-Galiano, M. J., De La Peña, M., Babaian, A., Bhatt, A. S., & Fire, A. Z. (2024). Viroid-like colonists of human microbiomes. Cell, 187(23), 6521-6536.e18. https://doi.org/10.1016/j.cell.2024.09.033
This article was originally published in the GENEWS May 2025 Issue.
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