title: Separate fusion of outer and inner mitochondrial membranes.
abstract: Mitochondria are enveloped by two closely apposed boundary membranes with different properties and functions. It is known that they undergo fusion and fission, but it has remained unclear whether outer and inner membranes fuse simultaneously, coordinately or separately. We set up assays for the study of inner and outer membrane fusion in living human cells. Inner membrane fusion was more sensitive than outer membrane fusion to inhibition of glycolysis. Fusion of the inner membrane, but not of the outer membrane, was abolished by dissipation of the inner membrane potential with K+ (valinomycin) or H+ ionophores (cccp). In addition, outer and inner membrane fusion proceeded separately in the absence of any drug. The separate fusion of outer and inner membranes and the different requirements of these fusion reactions point to the existence of fusion machineries that can function separately.
authors.affiliation: INSERM U582, Institut de Myologie, Université Pierre et Marie Curie, IFR14, Groupe Hospitalier Pitié-Salpêtrière, 47 blvd de l'Hôpital, 75651 Paris Cedex 13, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Malka
authors.forename: Olwenn
authors.initials: O
authors.lastname: Guillery
authors.forename: Carmen
authors.initials: C
authors.lastname: Cifuentes-Diaz
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Guillou
authors.forename: Pascale
authors.initials: P
authors.lastname: Belenguer
authors.forename: Anne
authors.initials: A
authors.lastname: Lombès
authors.forename: Manuel
authors.initials: M
authors.lastname: Rojo
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000968:Antimycin A / Q000494:pharmacology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002460:Cell Line; D003847:Deoxyglucose / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins; D008561:Membrane Fusion / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects / Q000648:ultrastructure*; D051336:Mitochondrial Membranes / Q000187:drug effects* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D014634:Valinomycin / Q000494:pharmacology; D000097573:Red Fluorescent Protein; D000098855:Collapsin Response Mediator Protein 1
chemical_list: D000255:Adenosine Triphosphate; D000968:Antimycin A; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D003847:Deoxyglucose; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D009840:Oligomycins; D014634:Valinomycin; D000097573:Red Fluorescent Protein; C102924:CRMP1 protein, human; D000098855:Collapsin Response Mediator Protein 1