RESUMO
An ability to comprehensively track the assembly intermediates (AIs) of complex I (CI) biogenesis in Drosophila will enable the characterization of the precise mechanism(s) by which various CI regulators modulate CI assembly. Accordingly, we generated 21 novel antibodies to various mitochondrial proteins and used this resource to characterize the mechanism by which apoptosis-inducing factor (AIF) regulates CI biogenesis by tracking the AI profile observed when AIF expression is impaired. We find that when the AIF-Mia40 translocation complex is disrupted, the part of CI that transfers electrons to ubiquinone is synthesized but fails to progress in the CI biosynthetic pathway. This is associated with a reduction in intramitochondrial accumulation of the Mia40 substrate, MIC19. Importantly, knockdown of either MIC19 or MIC60, components of the mitochondrial contact site and cristae organizing system (MICOS), fully recapitulates the AI profile observed when AIF is inhibited. Thus, AIF's effect on CI assembly is principally due to compromised intramitochondrial transport of the MICOS complex.
Assuntos
Fator de Indução de Apoptose/genética , Mitocôndrias/genética , Proteínas de Transporte da Membrana Mitocondrial/genética , Proteínas Mitocondriais/genética , Animais , Drosophila melanogaster/genética , Complexo I de Transporte de Elétrons/genética , Membranas Mitocondriais/metabolismo , Ligação Proteica/genéticaRESUMO
NADH:ubiquinone oxidoreductase, more commonly referred to as mitochondrial complex I (CI), is the largest discrete enzyme of the oxidative phosphorylation system (OXPHOS). It is localized to the mitochondrial inner membrane. CI oxidizes NADH generated from the tricarboxylic acid cycle to NAD+, in a series of redox reactions that culminates in the reduction of ubiquinone, and the transport of protons from the matrix across the inner membrane to the intermembrane space. The resulting proton-motive force is consumed by ATP synthase to generate ATP, or harnessed to transport ions, metabolites and proteins into the mitochondrion. CI is also a major source of reactive oxygen species. Accordingly, impaired CI function has been associated with a host of chronic metabolic and degenerative disorders such as diabetes, cardiomyopathy, Parkinson's disease (PD) and Leigh syndrome. Studies on Drosophila have contributed to our understanding of the multiple roles of CI in bioenergetics and organismal physiology. Here, we explore and discuss some of the studies on Drosophila that have informed our understanding of this complex and conclude with some of the open questions about CI that can be resolved by studies on Drosophila.
