The cell’s powerhouses: Molecular machines enable efficient energy production

Most living organisms on our planet-whether plants, animals, or humans -contain mitochondria in their cells. Their main function is to supply energy for nearly all cellular processes. To achieve this, mitochondria use the oxygen we breathe and carbohydrates from food to regenerate ATP, the universal energy currency of cells. This function is performed by proteins known as the respiratory complexes, which work together in the energy-generating process.

Although these respiratory complexes were discovered 70 years ago, their exact organization inside mitochondria has remained elusive until now. Using state-of-the-art cryo-electron tomography, researchers led by Dr. Florent Waltz and Prof. Ben Engel at the Biozentrum of the University of Basel were able to create high-resolution images of the respiratory chain directly inside cells at a resolution never achieved before. The results of the study are published in "Science".

Mitochondrial architecture for efficient energy production

"Our data show that the respiratory proteins organize in specific membrane regions of mitochondria, stick together and form one main type of supercomplex," explains Florent Waltz, SNSF Ambizione Fellow and first author of the study. "Using the electron microscope, individual supercomplexes were clearly visible – we could directly see their structures and how they work. The respiratory supercomplexes pump protons across the mitochondrial membrane. The ATP production complexes, which act similarly to a watermill, use this flow of protons to drive ATP generation."

The researchers examined mitochondria in living cells of the alga Chlamydomonas reinhardtii. “We were very surprised that all the proteins were actually organized in such supercomplexes," says Waltz. "This architecture might make ATP production more efficient, optimize electron flow, and minimize energy loss".