Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Route Cantonale, 1015 Lausanne, Switzerland; National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
Lina Carlini
Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Route Cantonale, 1015 Lausanne, Switzerland; National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
Tatjana Kleele
Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Route Cantonale, 1015 Lausanne, Switzerland; National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
Adai Colom
National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland; Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland; Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
Antoine Goujon
National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland; Department of Organic Chemistry, University of Geneva, 1211 Geneva, Switzerland
Stefan Matile
National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland; Department of Organic Chemistry, University of Geneva, 1211 Geneva, Switzerland
Aurélien Roux
National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland; Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland
Suliana Manley
Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Route Cantonale, 1015 Lausanne, Switzerland; National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland; Corresponding author
Summary: During mitochondrial fission, key molecular and cellular factors assemble on the outer mitochondrial membrane, where they coordinate to generate constriction. Constriction sites can eventually divide or reverse upon disassembly of the machinery. However, a role for membrane tension in mitochondrial fission, although speculated, has remained undefined. We capture the dynamics of constricting mitochondria in mammalian cells using live-cell structured illumination microscopy (SIM). By analyzing the diameters of tubules that emerge from mitochondria and implementing a fluorescence lifetime-based mitochondrial membrane tension sensor, we discover that mitochondria are indeed under tension. Under perturbations that reduce mitochondrial tension, constrictions initiate at the same rate, but are less likely to divide. We propose a model based on our estimates of mitochondrial membrane tension and bending energy in living cells which accounts for the observed probability distribution for mitochondrial constrictions to divide.