Universidad Michoacana de San Nicolás de Hidalgo MORELIA, Michoacan de Ocampo, Mexico
Eridani Olmos-Orizaba (Universidad Michoacana de San Nicolás de Hidalgo)| Olin Torres-Isidro (Universidad Michoacana de San Nicolás de Hidalgo)| Rocío Montoya-Pérez (Universidad Michoacana de San Nicolás de Hidalgo)| Alain Rodríguez-Orozco (Universidad Michoacana de San Nicolás de Hidalgo)| Elizabeth Calderón-Cortés (Universidad Michoacana de San Nicolás de Hidalgo)| Alfredo Saavedra-Molina (Universidad Michoacana de San Nicolás de Hidalgo)| Christian Cortés-Rojo (Universidad Michoacana de San Nicolás de Hidalgo)
Yeast cells uncouple its respiration by opening a mitochondrial unselective channel (MUC) that dissipates the membrane potential and accelerates oxygen consumption in order to avoid a deleterious buildup of ROS. Yeast incorporates polyunsaturated fatty acids (PUFA) into membranes when available in its environment, increasing the sensitivity of membranes to oxidative damage. One factor causing oxidative stress in yeast is ethanol accumulation during fermentation. The MUC is constituted by the voltage-dependent anionic channel (VDAC), the adenine nucleotide translocator and the cyclophilin D, being the VDAC a sensor for Ca2+ levels that promotes MUC closing under high Ca2+ concentrations. Moreover, MUC function is dependent on the phospholipid cardiolipin. In this work, we propose that yeast become more susceptible to ethanol stress when grow in the presence of PUFA by the impairment of MUC function due to enhanced lipid peroxidation. Yeast cells were grown in liquid YPD medium with (+C18:3) or without (-C18:3) 1mM linolenic acid and 10% ethanol. Ethanol decreased yeast growth by 20% and 90% in –C18:3 and +C18:3 cells, respectively. Ethanol also promoted lipid peroxidation only in +C18:3 cells. The addition of amiodarone, which increases cytosolic Ca2+ levels and promotes the closure of MUC, decreased 80% the growth in –C18:3 cells, while the +C18:3 cells showed the same levels of growth inhibition than without amiodarone. In – C18:3 cells respiring in uncoupled state (U), amiodarone decreased respiration by promoting MUC closing and coupling. Conversely, respiration was slightly inhibited by amiodarone in the +C18:3 cells. The role of MUC in the deleterious effects of ethanol in +C18:3 cells was confirmed in yeast mutants depleted in cardiolipin and VDAC, as these cells became insensitive to the effects of amiodarone. These results suggest that increased sensitivity to ethanol elicited by C18:3 may be due to impaired MUC function due to enhanced lipid peroxidation.
Support or Funding Information
This work was supported by a grant from Programa de Investigación 2021, Coordinación de la Investigación Científica ‐ UMSNH (CCR).