Age-related changes in abundance, posttranslational modification and supramolecular assembly of OxPhos enzymes in Podospora anserina

The filamentous fungus Podospora anserina is successfully employed as an experimental ageing model for nearly 60 years. Unlike most other fungi the life span of P. anserina is limited. Ageing of cultures is controlled by a complex network of molecular pathways in which those related to mitochondrial functions play a key role [1,2]. Numerous data support the notion that protein complexes and supercomplexes involved in oxidative phosphorylation play a crucial role in lifespan control. Especially the generation of ATP by the ATP synthase, energized by the respiratory chain complexes, is supposed to be a key factor for the ageing process. The ATP synthase and the other OxPhos complexes do form supramolecular assemblies that have an impact on cell metabolism, mitochondrial morphology, diseases, ageing and vice versa [3]. We have analysed the mitochondrial proteome of P. anserina of different age groups by native gel electrophoresis and LC-MS. For quantification gels were stained with fluorescence dyes. An age-related decrease in abundance of MF_oF₁ ATP synthase as well as of OxPhos complexes and supercomplexes (natural assemblies of the complexes I, III, and IV into stoichiometric entities, such as I₁III₂IV_0-2) was observed. Age-associated posttranslational modifications of the ATP synthase and of other mitochondrial proteins by mass spectrometry were analysed. Thereby specific oxidations of amino acids such as the conversion of tryptophan to hydroxy-tryptophan, N-formylkynurenine and kynurenine were quantitated. Global analyses by systems biology approaches are currently conducted to understand the interplay between protein activity control, energy conversion, oxidative stress and ageing.

This work was supported by the BMBF project GerontoMitoSys.