OXPHOS Proteins in Loco-Motion: Observation of Single Complexes In Cellulo

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Abstract

The relative arrangement of the OXPHOS complexes to each other is probably the key to their function, adaption, and coupling, resulting in measurable parameters like mitochondrial membrane-potential, ATP and NAD+/NADH levels and ROS (reactive oxygen species) production. This organization is determined by the fine structure of mitochondrial cristae, the OXPHOS microcompartments, and the formation of putative supercomplexes. To reveal the spatio-temporal organization of OXPHOS complexes in situ, we address these issues by single molecule based superresolution microscopy in mitochondria within live cells. We were able to show the movement of single F1FO ATP synthase within cristae. Our electron-microscopic and dual color superresolution data suggest that F1FO ATP synthase is found not only at the rims but also in the sheet region of cristae. We suggest that this is the monomeric form, while dimeric/oligomeric F1FO ATP synthase, the structure shaping form, is accumulated at the rims. By determination of local pH values at complex IV (cytochrome c oxidase) and dimeric F1FO ATP synthase, we found a lateral pH gradient with higher pH at the sink. We will present evidence that the fine structure of the inner membrane influences the local pH and thus the proton motive force.

Speakers from the University of Münster

Busch, Karin

Professur für Zoologie und Molekulare Zellbiologie (Prof. Busch)