Their results show that the proteins responsible for energy production, known as the respiratory complex, do not act alone. Instead, they assemble into large structures called "supercomplexes," which play a key role in the efficient production of ATP, the cell's main energy source.
Mitochondria are found in the cells of almost all living organisms, including plants, animals, and humans. They use the oxygen we breathe and the carbohydrates in our food to produce ATP, which powers the basic functions of cells, thereby producing energy.
Although these respiratory chain complexes were discovered 70 years ago, their exact organization within mitochondria is still unknown. Using state-of-the-art cryo-electron tomography technology, researchers led by Dr. Florent Waltz and Professor Ben Engel at the Biocenter of the University of Basel were able to create high-resolution images of the respiratory chain directly within cells with unprecedented resolution. The findings were published in the journal Science.
"Our data show that respiratory proteins organize themselves in specific membrane regions of the mitochondria and stick together to form one major type of supercomplex," explains Florent Waltz, researcher at SNSFAmbizione and first author of the study. "Using electron microscopy, the individual supercomplexes are clearly visible - we can directly see how they structure and work. The respiratory supercomplex pumps protons across the mitochondrial membrane. The ATP-generating complex acts like a water mill, using this flow of protons to drive ATP production."
The researchers examined mitochondria in living cells of Chlamydomonas reinhardtii. "We were very surprised that all the proteins were actually organized into supercomplexes like this," Walz said. "This structure may make ATP production more efficient, optimize electron flow, and minimize energy loss."
In addition to the supercomplex, the researchers were also able to examine the mitochondrial membrane structure more closely. "It's somewhat reminiscent of lung tissue: the inner mitochondrial membrane has many folds that increase the surface area to accommodate as many respiratory complexes as possible," Engel said.
In the future, the researchers aim to uncover why respiratory complexes are interconnected and how this synergy increases the efficiency of cellular respiration and energy production. The research may also provide new insights into biotechnology and health.
"By studying the structure of these complexes in other organisms, we can gain a broader understanding of their basic organization," explains Walz. "Not only could this reveal evolutionary adaptations, it could also help us understand why disruption of these complexes leads to human disease."
Compiled from /ScitechDaily