Abstract
Defects in mitochondrial electron transport chain (ETC) function have been implicated in a number of neurodegenerative disorders, cancer, and aging. Mitochondrial complex I (NADH dehydrogenase) is the largest and most complicated enzyme of the ETC with 45 subunits originating from two separate genomes. The biogenesis of complex I is an intricate process that requires multiple steps, subassemblies, and assembly factors. Here, we report the generation and characterization of a Drosophila model of complex I assembly factor deficiency. We show that CG7598 (dCIA30), the Drosophila homolog of human complex I assembly factor Ndufaf1, is necessary for proper complex I assembly. Reduced expression of dCIA30 results in the loss of the complex I holoenzyme band in blue-native polyacrylamide gel electrophoresis and loss of NADH:ubiquinone oxidoreductase activity in isolated mitochondria. The complex I assembly defect, caused by mutation or RNAi of dCIA30, has repercussions both during development and adulthood in Drosophila, including developmental arrest at the pupal stage and reduced stress resistance during adulthood. Expression of the single-subunit yeast alternative NADH dehydrogenase, Ndi1, can partially or wholly rescue phenotypes associated with the complex I assembly defect. Our work shows that CG7598/dCIA30 is a functional homolog of Ndufaf1 and adds to the accumulating evidence that transgenic NDI1 expression is a viable therapy for disorders arising from complex I deficiency.
Highlights
Alterations in mitochondrial energy metabolism have been implicated in aging and age-onset disease [1]
We demonstrate that flies carrying a mutation in dCIA30 display a reduction of complex I holoenzyme in blue native polyacrylamide gel electrophoresis (BN-PAGE) to undetectable levels
We have demonstrated the role of CG7598/dCIA30, the Drosophila homolog of human Ndufaf1, as a vital factor in the assembly of mitochondrial complex I
Summary
Alterations in mitochondrial energy metabolism have been implicated in aging and age-onset disease [1]. Proper assembly of complex I is intimately associated with the presence of a multitude of assembly factors and chaperones, and their loss results in diseases that mimic complex I subunit defects [3]. Complex I assembly factors were first isolated in studies of Neurospora crassa mutants that accumulated complex I subassemblies, with associated assembly factors, due to a mutation in a membrane arm subunit [8]. Of the two complex I intermediate associated (CIA) proteins identified in this study, only the 30 kDa protein (CIA30) has been shown to have a human homolog (NDUFAF1) [9] that functions as an assembly factor, interacting with mid-stage membrane arm subassemblies but not with a fully assembled holoenzyme or a late-stage subunit. Complete deletion of CIA30 in N. crassa result in complete loss of complex I and respiration exclusively via an alternative internal NADH:ubiquinone oxidoreductase [8]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
