A new class of genetic entities dubbed “obelisks” has been uncovered hiding in the human microbiome according to a new study. Nobel Prize winner Andrew Fire and colleagues found nearly 30,000 obelisks by analyzing microbiome databases.
Obelisks are prevalent, making up over 50% of some mouth samples tested. Yet their function and purpose is entirely unknown. They are described as a tiny ring of RNA that can fold into a rod shape, distinct from other genetic agents like viruses.
Obelisks can produce unique proteins named “oblins”, unlike similar viroids. This gives them lifelike properties, but it’s unclear if they are actually alive. They rely on microbial hosts, with one identified so far – a mouth bacteria called Streptococcus sanguinis.
In recent years, tens of thousands of new viroid-like organisms have been found, making scientists rethink classification and evolution at microscopic scales. As researcher Mark Peifer states: “The more we look, the more crazy things we see.”
Key mysteries around obelisks remain – how they spread, what they do to hosts, and what other hosts they inhabit. If confirmed to be a new lifeform, it would require updating biology textbooks. The researchers call them a novelty implying much has yet to learned about their interactions.