title: Regulation of mitochondrial phospholipids by Ups1/PRELI-like proteins depends on proteolysis and Mdm35.
abstract: The mitochondrial phospholipid metabolism critically depends on members of the conserved Ups1/PRELI-like protein family in the intermembrane space. Ups1 and Ups2 (also termed Gep1) were shown to regulate the accumulation of cardiolipin (CL) and phosphatidylethanolamine (PE), respectively, in a lipid-specific but coordinated manner. It remained enigmatic, however, how the relative abundance of both phospholipids in mitochondrial membranes is adjusted on the molecular level. Here, we describe a novel regulatory circuit determining the accumulation of Ups1 and Ups2 in the intermembrane space. Ups1 and Ups2 are intrinsically unstable proteins, which are degraded by distinct mitochondrial peptidases. The turnover of Ups2 is mediated by the i-AAA protease Yme1, whereas Ups1 is degraded by both Yme1 and the metallopeptidase Atp23. We identified Mdm35, a member of the twin Cx(9)C protein family, as a novel interaction partner of Ups1 and Ups2. Binding to Mdm35 ensures import and protects both proteins against proteolysis. Homologues to all components of this pathway are present in higher eukaryotes, suggesting that the regulation of mitochondrial CL and PE levels is conserved in evolution.
authors.affiliation: Institute for Genetics, Center for Molecular Medicine (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Potting
authors.forename: Claudia
authors.initials: C
authors.lastname: Wilmes
authors.forename: Tanja
authors.initials: T
authors.lastname: Engmann
authors.forename: Christof
authors.initials: C
authors.lastname: Osman
authors.forename: Thomas
authors.initials: T
authors.lastname: Langer
mesh_terms: D049069:ATP-Dependent Proteases / Q000378:metabolism; D017124:Conserved Sequence; D045726:Metalloproteases / Q000378:metabolism; D050296:Microbial Viability; D024101:Mitochondrial Proteins / Q000378:metabolism*; D008954:Models, Biological; D010743:Phospholipids / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: C552370:Mdm35 protein, S cerevisiae; D024101:Mitochondrial Proteins; D010743:Phospholipids; D029701:Saccharomyces cerevisiae Proteins; C512497:Ups1 protein, S cerevisiae; C542159:Ups2 protein, S cerevisiae; C519195:ATP23 protein, S cerevisiae; D045726:Metalloproteases; D049069:ATP-Dependent Proteases; C082702:YME1 protein, S cerevisiae