title: Redefining the roles of mitochondrial DNA-encoded subunits in respiratory Complex I assembly.
abstract: Respiratory Complex I deficiency is implicated in numerous degenerative and metabolic diseases. In particular, mutations in several mitochondrial DNA (mtDNA)-encoded Complex I subunits including ND4, ND5 and ND6 have been identified in several neurological diseases. We previously demonstrated that these subunits played essential roles in Complex I assembly which in turn affected mitochondrial function. Here, we carried out a comprehensive study of the Complex I assembly pathway. We identified a new Complex I intermediate containing both membrane and matrix arms at an early assembly stage. We find that lack of the ND6 subunit does not hinder membrane arm formation; instead it recruits ND1 and ND5 enters the intermediate. While ND4 is important for the formation of the newly identified intermediate, the addition of ND5 stabilizes the complex and is required for the critical transition from Complex I to supercomplex assembly. As a result, the Complex I assembly pathway has been redefined in this study.
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Rasika
authors.initials: R
authors.lastname: Vartak
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Janice
authors.initials: J
authors.lastname: Deng
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Hezhi
authors.initials: H
authors.lastname: Fang
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA. Electronic address: baiy@uthscsa.edu.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Bai
mesh_terms: D000818:Animals; D002460:Cell Line; D004272:DNA, Mitochondrial / Q000235:genetics*; D042967:Electron Transport Complex I / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D021122:Protein Subunits; D042967:Electron Transport Complex I
keywords: Assembly; Mitochondrial DNA mutations; ND4; ND5; ND6; Respiratory Complex I