Mitochondria Were Parasites Before They Were Powerhouses

Mitochondria, which power the cells of plants and animals, were reportedly energy parasites before they were the beneficial powerhouses they are today, according to new research.

Mitochondria came onto the scene about two billion years ago, and still little is known about their origins.

"We believe this study has the potential to change the way we think about the event that led to mitochondria," Martin Wu, a biologist at the University of Virginia (UV) and the study's lead author, said in a statement. "We are saying that the current theories - all claiming that the relationship between the bacteria and the host cell at the very beginning of the symbiosis was mutually beneficial - are likely wrong."

As an alternative to these past theories, the new study suggests that early mitochondria were parasitic, and only became beneficial after switching the direction of their ATP (adenosine triphosphate) transport years down the road.

"We reconstructed the gene content of mitochondrial ancestors, by sequencing DNAs of its close relatives, and we predict it to be a parasite that actually stole energy in the form of ATP from its host - completely opposite to the current role of mitochondria," Wu said.

Researchers used next-generation DNA sequencing technologies to decode the genomes of 18 bacteria that are close relatives of mitochondria. Through this technique, the UV team was also able to pinpoint human genes that were derived from mitochondria, which could help them gain insight into the genetic basis of human mitochondrial dysfunctions contributing to several diseases. Some of these conditions include "Alzheimer's disease, Parkinson's disease and diabetes, according to researchers.

The findings were published in the journal PLOS ONE.