title: Mitochondrial dynamics generate equal distribution but patchwork localization of respiratory Complex I.
abstract: Highly dynamic mitochondrial morphology is a prerequisite for fusion and fission. Mitochondrial fusion may represent a rescue mechanism for impaired mitochondria by exchanging constituents (proteins, lipids and mitochondrial DNA) and thus maintaining functionality. Here we followed for the first time the dynamics of a protein complex of the respiratory chain during fusion and fission. HeLa cells with differently labelled respiratory Complex I were fused and the dynamics of Complex I were investigated. The mitochondrial proteins spread throughout the whole mitochondrial population within 3 to 6 h after induction of cell fusion. Mitochondria of fused cells displayed a patchy substructure where the differently labelled proteins occupied separate and distinct spaces. This patchy appearance was already--although less pronounced--observed within single mitochondria before fusion, indicating a specific localization of Complex I with restricted diffusion within the inner membrane. These findings substantiate the view of a homogenous mitochondrial population due to constantly rearranging mitochondria, but also indicate the existence of distinct inner mitochondrial sub-compartments for respiratory chain complexes.
authors.affiliation: Kinematic Cell Research Group, Institute for Cell Biology and Neuroscience, JW Goethe University, Frankfurt/Main, Germany. k.busch@em.uni-frankfurt.de
authors.forename: Karin B
authors.initials: KB
authors.lastname: Busch
authors.forename: Juergen
authors.initials: J
authors.lastname: Bereiter-Hahn
authors.forename: Ilka
authors.initials: I
authors.lastname: Wittig
authors.forename: Hermann
authors.initials: H
authors.lastname: Schagger
authors.forename: Marina
authors.initials: M
authors.lastname: Jendrach
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D042967:Electron Transport Complex I / Q000378:metabolism*; D005453:Fluorescence; D006367:HeLa Cells; D006801:Humans; D008561:Membrane Fusion; D008928:Mitochondria / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D051336:Mitochondrial Membranes / Q000378:metabolism*; D014162:Transfection; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D042967:Electron Transport Complex I