Dangerous bacterium hosts intermediary genetic remnant


Nope. No angels on pinheads.

Within a dangerous stomach bacterium, Yale University researchers have discovered an ancient but functioning genetic remnant from a time before DNA existed.

To the surprise of researchers, this RNA complex seems to play a critical role in the ability of the organism to infect human cells, a job carried out almost exclusively by proteins produced from DNA’s instruction manual.

“What these cells are doing is using ancient RNA technology to control modern gene expression,” said Ron Breaker…investigator for the Howard Hughes Medical Institute and senior author of the study.

In old textbooks, RNA was viewed simply as the chemical intermediary between DNA’s instruction manual and the creation of proteins. However, Breaker’s lab has identified the existence and function of riboswitches, or RNA structures that have the ability to detect molecules and control gene expression – an ability once believed to be possessed solely by proteins. Breaker and many other scientists now believe the first forms of life depended upon such RNA machines, which would have had to find ways to interact and carry out many of the functions proteins do today.

The new paper describes the complex interactions of two small RNA molecules and two larger RNA molecules that together influence the function of a self-splicing ribozyme, a structure many biologists had believed had no role other than to reproduce itself. The new study, however, suggests that in the pathogenic stomach bacterium Clostridium difficile, this RNA structure acts as a sort of sensor to help regulate the expression of genes, probably to help the bacterium manipulate human cells.

“They were though to be molecular parasites, but it is clear they are being harnessed by cells to do some good for the organism,” Breaker said.

This is the sort of RNA structure that would have been needed for life existing before the evolution of double-stranded DNA, with its instruction book for proteins that carry out almost all of life’s functions today.

Interesting research – of the chicken or egg variety.

Sooner or later, the research will appear on a free site for us ordinary mortals to wander through.

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