Fmc1, a nuclear gene in yeast, is crucial for the assembly/stability of the mitochondrial F₁ sector of the ATP synthase at elevated temperatures (37 °C). It codes for a soluble protein located in the mitochondrial matrix and is associated with the oxidative phosphorylation pathway, which is vital for energy production in cells [1].

In yeast cells lacking Fmc1p, at 37 °C, the α-F₁ and β-F₁ proteins are synthesized, transported, and processed but form aggregates instead of incorporating into a functional F₁ oligomer. However, increasing the expression of Atp12p can compensate for the absence of Fmc1p. The deletion mutant Δfmc1 shows very slow growth on respiratory substrates at 37 °C, which can be rescued by overexpressing Odc1p. This rescuing mechanism involves increasing the flux of tricarboxylic acid cycle intermediates into mitochondria, leading to more substrate-level-dependent ATP synthesis [1,2].

In conclusion, Fmc1 is essential for proper mitochondrial F₁-ATPase assembly and stability under heat stress conditions in yeast. The study of Fmc1 in yeast models provides insights into the molecular mechanisms underlying mitochondrial function and energy metabolism, which may have implications for understanding related pathologies associated with oxidative phosphorylation system defects in higher organisms [1,2].

References:

1. Lefebvre-Legendre, L, Vaillier, J, Benabdelhak, H, Slonimski, P P, di Rago, J P. 2000. Identification of a nuclear gene (FMC1) required for the assembly/stability of yeast mitochondrial F(1)-ATPase in heat stress conditions. In The Journal of biological chemistry, 276, 6789-96. doi:. https://pubmed.ncbi.nlm.nih.gov/11096112/

2. Schwimmer, Christine, Lefebvre-Legendre, Linnka, Rak, Malgorzata, di Rago, Jean-Paul, Rigoulet, Michel. 2005. Increasing mitochondrial substrate-level phosphorylation can rescue respiratory growth of an ATP synthase-deficient yeast. In The Journal of biological chemistry, 280, 30751-9. doi:. https://pubmed.ncbi.nlm.nih.gov/15975925/