title: The i-AAA protease YME1L and OMA1 cleave OPA1 to balance mitochondrial fusion and fission.
abstract: Mitochondrial fusion and structure depend on the dynamin-like GTPase OPA1, whose activity is regulated by proteolytic processing. Constitutive OPA1 cleavage by YME1L and OMA1 at two distinct sites leads to the accumulation of both long and short forms of OPA1 and maintains mitochondrial fusion. Stress-induced OPA1 processing by OMA1 converts OPA1 completely into short isoforms, inhibits fusion, and triggers mitochondrial fragmentation. Here, we have analyzed the function of different OPA1 forms in cells lacking YME1L, OMA1, or both. Unexpectedly, deletion of Oma1 restored mitochondrial tubulation, cristae morphogenesis, and apoptotic resistance in cells lacking YME1L. Long OPA1 forms were sufficient to mediate mitochondrial fusion in these cells. Expression of short OPA1 forms promoted mitochondrial fragmentation, which indicates that they are associated with fission. Consistently, GTPase-inactive, short OPA1 forms partially colocalize with ER-mitochondria contact sites and the mitochondrial fission machinery. Thus, OPA1 processing is dispensable for fusion but coordinates the dynamic behavior of mitochondria and is crucial for mitochondrial integrity and quality control.
authors.affiliation: Institute for Genetics, Center for Molecular Medicine (CMMC), and 2 Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
authors.forename: Ruchika
authors.initials: R
authors.lastname: Anand
authors.forename: Timothy
authors.initials: T
authors.lastname: Wai
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Baker
authors.forename: Nikolay
authors.initials: N
authors.lastname: Kladt
authors.forename: Astrid C
authors.initials: AC
authors.lastname: Schauss
authors.forename: Elena
authors.initials: E
authors.lastname: Rugarli
authors.forename: Thomas
authors.initials: T
authors.lastname: Langer
mesh_terms: D000818:Animals; D017209:Apoptosis; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D045726:Metalloproteases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008928:Mitochondria / Q000201:enzymology / Q000648:ultrastructure; D063154:Mitochondrial Dynamics; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D053142:Mitochondrial Size; D053140:Organelle Shape; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport
chemical_list: D020558:GTP Phosphohydrolases; D008666:Metalloendopeptidases; D045726:Metalloproteases; D024101:Mitochondrial Proteins; D021122:Protein Subunits; C572960:OMA1 protein, mouse; C000588588:Yme1l1 protein, mouse; C498809:Opa1 protein, mouse