Researchers show mitochondria shed membranes
- UCLA and Peking University researchers posted a bioRxiv preprint showing Toxoplasma gondii pushes host mitochondria to shed outer-membrane sacs that mature into new compartments. - The team says those sacs, called SPOTs, become acidified multivesicular compartments that engulf host proteins and lysosomes; blocking acidification slowed parasite proliferation. - The work extends a 2022 Science report on SPOT shedding and links it to organelle formation during infection (biorxiv.org).
Mitochondria are the cell’s double-walled power plants, with an outer membrane that separates them from the rest of the cell. A new bioRxiv preprint says the parasite *Toxoplasma gondii* can make host mitochondria shed pieces of that outer layer into new compartments. (biorxiv.org) The paper, posted April 23, 2026, is from Lena Pernas, Xianhe Li, Yubai Sun and Jose M. Delgado at University of California, Los Angeles and Peking University. The authors describe acidified compartments derived from host mitochondria that help the parasite grow. (biorxiv.org) The structures are called SPOTs, short for “structures positive for outer mitochondrial membrane.” The preprint says infected cells shed large SPOTs from mitochondria, and those SPOTs then mature into multivesicular compartments. (biorxiv.org) In plain terms, the sacs act less like broken scraps and more like sealed sorting rooms. The authors report that mature SPOTs engulf cytosolic proteins and functional lysosomes, then acidify their interior. (biorxiv.org) The parasite appears to help build them. The preprint says SPOTs needed host endosomal sorting complexes required for transport, or ESCRT machinery, plus the parasite effector TgGRA7 to acquire lysosomes and acidify. (biorxiv.org) When the team disrupted SPOT acidification, *Toxoplasma* proliferation fell. That ties the membrane-shedding process to parasite fitness, not just a strange change in cell shape. (biorxiv.org) This builds on a 2022 *Science* paper from Xianhe Li, Lena F. Pernas and colleagues, which reported that *Toxoplasma* infection triggers mitochondria to shed SPOTs in response to outer-membrane stress. That earlier study linked SPOT formation to the parasite effector TgMAF1 and host proteins TOM70 and SAM50. (pubmed.ncbi.nlm.nih.gov) (science.org) The new preprint pushes the idea further: not only can mitochondria shed membrane under stress, the shed material can mature into a compartment with a distinct job during infection. Nature’s news coverage said the findings revive a long-running question about whether mitochondria can generate brand-new organelles with specialized functions. (nature.com) (biorxiv.org) The result is still a preprint, which means it has not yet been peer reviewed. But if the data hold up, the picture of mitochondria shifts from static powerhouses to membrane donors that pathogens can redirect into new cellular architecture. (biorxiv.org) (nature.com)
