An international team led by Nobel Prize winner Andrew Fire and involving the Institute of Molecular and Cellular Biology of Plants (IBMCP), a joint center of the Polytechnic University of Valencia (UPV) and the Higher Council for Scientific Research (CSIC), a dependent organization of the Ministry of Science, Innovation and Universities (MICIU), has discovered a new biological entity in the bacteria that live in our mouth and intestines.
This organism, which they have called Obelisk because of its shape, is a new infectious agent whose genome is simpler than that of viruses, and whose function and effects on our health are still unknown. This discovery, made through bioinformatic studies of genetic sequences obtained from human feces, opens new questions about the origin and evolution of microbiological diversity. The discovery is published today in the journal cell.
The microbiome is a complex microbiological ecosystem that resides throughout our bodies. It hosts an astonishing diversity of microorganisms that includes everything from viruses and bacteria to fungi and protozoa. We know more and more about this intricate biological network and its crucial role in health, intervening in functions as varied as digestion, the immune system or even our own behavior.
Now, a multidisciplinary team led by the Nobel Prize in Medicine Andrew Fire at Stanford University (USA), in collaboration with the CSIC researcher’s team Marcos de la Peña at the IBMCP in Valencia and the University of Toronto (Canada), have revealed an additional layer of complexity to our inner microscopic world: Obelisks, minimal biological entities never seen before and that challenge our understanding of the limits of life.
Discovery in the human microbiome
Obelisks are novel infectious agents with a tiny circular RNA genome of only 1,000 nucleotides, far below the RNA genomes that some viruses use to reproduce. “These RNA circles are highly self-complementary, which allows them to adopt a stable rod-shaped structure reminiscent of the Egyptian monuments that give them their name,” explains Marcos de la Peña. “They lack the protein coat that characterizes viruses, but, like viruses, they are capable of encoding proteins,” points out the CSIC researcher.
As a scientist who works in a plant research center, de la Peña points out that the Obelisks are reminiscent of viroids, a family of subviral agents that infect plants and with which they share the circular RNA genome and the usual presence of self-cutting ribozymes. . “However, plant viroids are even tinier, about 300 or 400 nucleotides, and do not code for proteins. For all these reasons, the Obelisks are halfway between viruses and viroids, which poses a challenge to their origin and classification,” says the researcher.
The discovery of the Obelisks has been possible thanks to bioinformatics studies of genetic sequences obtained from human feces, the presence of these RNAs being detected in 7% of the 440 subjects analyzed. Massive bioinformatics analyzes also allowed the discovery of nearly 30,000 species of Obelisks in biological samples collected throughout the planet, both in natural ecosystems (soils, rivers, oceans…) and in wastewater or animal microbiomes.
Among all these data, it was detected that a strain of Streptococcus sanguinisa common commensal bacteria in the microbiota of our mouth, accumulates Obelisks in a very abundant way, and it was found that around half of the population analyzed contained Obelisks in their oral cavity.
New frontier in biology
The function and effects of the Obelisks and the proteins they encode are still a mystery, the researchers recall. The high accumulation of RNA genomes inside bacteria would indicate, according to scientists, a possible role in the regulation of cellular activity with significant implications for health, since the microbiomes where these bacteria live influence numerous physiological aspects, from digestion to the immune system.
Furthermore, the discovery of the Obelisks raises fundamental questions about the origin and evolution of viruses and microbiological diversity. According to De la Peña, “this discovery shows that the microbial world is much more complex than we imagined. “We have opened a door to a whole new field of exploration that can revolutionize our understanding of Virology, Biology and even the very origin of life on Earth.”
#discover #biological #entity #lives #human #body #obelisks
