The structural mechanism of MCIA complex assembly links mitochondrial redox pathways

Autor: Lindsay McGregor, Samira Acajjaoui, Ambroise Desfosses, Melissa Saïdi, Maria Bacia-Verloop, Jennifer J. Schwarz, Pauline Juyoux, Jill von Velsen, Matthew W. Bowler, Andrew McCarthy, Eaazhisai Kandiah, Gordon Leonard, Irina Gutsche, Montserrat Soler-Lopez
Rok vydání: 2023
DOI: 10.1101/2023.02.23.529646
Popis: The mitochondrial Complex I assembly (MCIA) complex is an essential player in the biogenesis of respiratory Complex I (CI), the multiprotein complex responsible for the initiation of oxidative phosphorylation (OXPHOS). It is not well understood how MCIA facilitates the assembly of CI. Here we report the structural basis of the complex formation between the MCIA subunits ECSIT and ACAD9. ECSIT binding induces a major conformational change in the FAD-binding loop of ACAD9, resulting in efflux of the FAD cofactor and redeployment of ACAD9 from fatty acid β-oxidation (FAO) to CI assembly. We identify an adjacent α-helix as a key structural element that specifically enables the CI assembly functionality of ACAD9, distinguishing it from its closely related VLCAD counterpart. Furthermore, we show that ECSIT is phosphorylatedin vitroandex celluloand provide evidence that phosphorylation downregulates its association with ACAD9. Interestingly, ECSIT has previously been linked to the pathogenesis of Alzheimer’s disease and here we show that ECSIT phosphorylation in neuronal cells is reduced upon exposure to amyloid-β (Aβ) oligomers.These findings shed light on the assembly of the MCIA complex and implicate ECSIT as a potential reprogrammer of bioenergetic metabolic pathways that can be altered when mitochondria are affected by Aβ toxicity, a hallmark of Alzheimer’s disease.
Databáze: OpenAIRE