Baranowska, E. | bioRxiv Science

bioRxiv2024

Profiling of yeast Saccharomyces cerevisiae mitochondrial AMPylome reveals a regulation of ATP synthase coupling trough subunit delta

The adenylation (AMPylation) of proteins as a posttranslational modification is used by bacteria during infection of host cells. These new virulence factors - AMPylases mainly belonging to the FIC domain containing proteins and constitute a potential drug target. Human FIC protein (HYPE) controls the activity of BiP chaperone under endoplasmic reticulum stress. No FIC family proteins have yet been identified in yeast Saccharomyces cerevisiae. The second family of AMPylases are SelO proteins which control the redox homeostasis in mitochondria and chloroplasts. We describe here the first global screening of AMPylated proteins in yeast S. cerevisiae mitochondrial proteome from wild type and SelO (Fmp40) lacking cells. Through quantitative mass-spectrometry-based proteomics, we identified a total of 169 AMPylated proteins in mitochondria while AMPylated peptides of 115 proteins were identified in fmp40{Delta} mitochondria, indicating on the presence of another, besides Fmp40, not yet identified AMPylase in yeast. We confirmed AMPylation of Atp1, Atp2, Atp3 and Atp16 subunits of mitochondrial ATP synthase by western blotting. Interestingly, we found AMPylation and phosphorylation of many residues, what indicates on the complex regulation of the ATP synthase activity. We confirmed the importance of one of such residues in Atp16, showing that its post-translational modification serves to regulate ATP synthase and OXPHOS coupling in both fermentative and respiratory growth conditions. This regulation serves to maintain the proper potential of the inner mitochondrial membrane, particularly under conditions of fermentative growth. This dataset represents the first library of AMPylated mitochondrial yeast proteins reported to date and supplements the AMPylome of human chronic lymphocytic leukemia cell line from human HYPE containing and HYPE lacking cells. The data represents a foundation for substrate specific investigations that can ultimately decipher the biological role of the AMPylation in the mitochondria.

molecular biology↗

bioRxiv2022

Small Protein Interactome analysis of ATP synthase identifies the uncharacterized 'subunit' Mco10 - a new modulator of permeability transition pore in S. cerevisiae

In S. cerevisiae, the uncharacterized protein Mco10 (Mitochondrial class one protein of 10 kDa) was previously found to be associated with mitochondrial ATP synthase and referred to as a new subunit l. However, recent cryo-EM structures of S. cerevisiae ATP synthase could not ascertain Mco10 as a structural subunit of the enzyme, either monomers or dimers, making questionable its role as a structural subunit. The N-terminal part of Mco10 is very similar to Atp19 (subunit k) of ATP synthase. The subunit k/Atp19, along with the subunits g/Atp20 and e/Atp21 plays a major role in stabilization of the ATP synthase dimers. In our effort to confidently define the small protein interactome of ATP synthase we similarly found Mco10 associated with ATP synthase of S. cerevisiae. We herein investigated the impact of Mco10 on ATP synthase functioning. Biochemical analysis revealed in spite of similarity in sequence and evolutionary lineage, that Mco10 and Atp19 differ significantly in function. This is the first work to show Mco10 is an auxiliary ATP synthase subunit that only functions in permeability transition.

cell biology↗