Scientists map parasite mitochondria, uncovering 33 potential drug targets for neglected diseases

Vamsi Mootha had a simple idea: if you want to kill a parasite, cut off its power supply. That thought anchored a four-year international effort to map every protein inside the mitochondria of five parasites responsible for some of the world's most stubborn tropical diseases. The parasites—those causing sleeping sickness, giardiasis, leishmaniasis, and babesiosis—sicken nearly a billion people annually. Together with a consortium of 25 scientists from Harvard's School of Public Health, Harvard Medical School, the Broad Institute, Massachusetts General Hospital, and Boston University, Mootha's team set out to catalog the complete protein architecture of these cellular power plants, spanning a billion years of evolutionary history.

The technical challenge was formidable. The researchers needed a single, reliable method that could work across five different organisms without sacrificing accuracy. They spent more than a year testing approaches before settling on protein correlation profiling: breaking apart each organism's cells, then using mass spectrometry to track which proteins moved together with known mitochondrial components. Proteins that consistently traveled with the mitochondria, batch after batch, could be confidently added to the inventory—even ones that had never been linked to the organelle before. The payoff was nine published papers and a detailed map of mitochondrial architecture across organisms that had never been studied this way.

The immediate practical goal was drug discovery. Scientists already knew that targeting mitochondria worked: atovaquone, a malaria drug, kills the parasite by blocking a single mitochondrial protein. Mootha's team searched for protein families shared across the mitochondria of trypanosomes, Leishmania, Acanthamoeba, and Babesia—but crucially, absent from human mitochondria. Finding such targets meant a drug could theoretically kill multiple parasites without poisoning the patient. The team identified 33 protein families that fit this profile, each one a potential starting point for a medication that could treat several diseases at once. Mootha was careful to emphasize that these were early findings; the distance from a promising target to a safe, effective drug remains long. But it was a concrete first step.

What emerged from the data challenged fundamental assumptions about how mitochondria work. The textbook version—aerobic powerhouses that carry their own DNA—holds true for humans and yeast, but it tells only part of the story. Giardia's mitochondria have abandoned DNA entirely, retaining just 59 proteins, more than half of unknown function. Acanthamoeba's mitochondria, by contrast, are unexpectedly sophisticated: they run on oxygen like human mitochondria, but also carry a backup enzyme called hydrogenase that lets them produce hydrogen gas when oxygen grows scarce. These weren't aberrations. They were windows into evolutionary history. The parasites had retained ancient mitochondrial machinery that human mitochondria had discarded over millions of years. In a sense, Mootha observed, human mitochondria were the oddball—stripped down and specialized, while these parasites carried the more flexible, versatile versions from the deep past.

The team used their experimental data to train an artificial intelligence model that predicted mitochondrial proteins across nearly 200 eukaryotic organisms, most of which had never been studied directly. This allowed them to reconstruct the gains and losses that shaped modern mitochondria and to model what the mitochondrion of LECA—the last common ancestor of all living eukaryotes—might have looked like a billion years ago. The result was surprising: LECA's mitochondrion was not simple or stripped down, but sophisticated and metabolically flexible, capable of generating energy whether oxygen was present or absent. The team also found that when different lineages independently lost their mitochondrial DNA, the rest of the organelle shrank too, sometimes dramatically, suggesting that DNA loss and organellar simplification were linked processes.

Mootha and his collaborators have made all their data publicly available, hoping it becomes a lasting resource for the field. The goal, he emphasized, was not simply to create inventories for their own sake, but to enable future researchers to work faster and think deeper. The map of parasite mitochondria is now in the hands of the scientific community, waiting to be mined for the next generation of drug candidates and evolutionary insights.