N-ACETYL CYSTEINE IMPROVES CELLULAR GROWTH IN SACCHAROMYCES CEREVISIAE RESPIRATORY DEFICIENT STRAIN

GRONDONA, F. G.; UTGE, S.; PICHETTO OLANDA, I.; STELLA, C.

Salta

Congreso; Reunión Conjunta por el XIV Congreso de la Pan-American Association for Biochemistry and Molecular Biology y LV Reunión Anual; 2019

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

Reactive oxygen species (ROS) is a main factor that alters cellular physiology and functionality. Many strategies are used in order to control excessive oxidative stress. One strategy includes the use of antioxidants like N-Acetyl cysteine (NAC). Studies on Saccharomyces cerevisiae yeast have shown that the NAC molecule has an antioxidant effect. Using a simple system such as yeast allows assays in which current factors are more restricted or manageable than in higher organism. Due to Saccharomyces cerevisiae yeast metabolism, these cells can grow under both aerobic and anaerobic conditions. This is an interesting biochemical feature when planning research that mimic hypoxia and re-oxygenation cycles which are detected in pathological situations of higher organisms; such as sepsis and septic shock, pathological pregnancies and ischemia-reperfusion injury. It is known that in S. cerevisaie cells, NAC decreases the formation of reactive oxygen species (ROS) under aerobic growth conditions, and also prevents cyt c release and caspase-like activation. The aim of this study was to compare the effect of this antioxidant on ROS production and cellular growth of a wild type cell and a respiratory deficient strain. Cells of the wild strain MMY2 and its respiratory deficiency grew in YPD medium (yeast, peptone, glucose) for 48 hours. An aliquot was suspended in potassium acid phthalate buffer (pH = 4.5) in the presence of a final NAC concentration of 0.20 or 0.35 mg /mL. Incubation was continued for 72 hours and at its term cell viability was determined. As an indirect measure of the ROS level, the fluorescence signal of 2´, 7´-dichlorofluorescein diacetate (DCFH-DA) was determined. In addition, the capacity of the NAC to stimulate the reducing power of the yeast was established using the change of color Methylene Blue (MB) indicator. As it is found in the present work a reducing environment exerted by NAC presence during incubation of the cells allows a deficient respiratory strain to improve its cellular growth. It seems likely that the energy production or the phenotype which characterizes a deficient strain is incapable to palliate ROS growth inhibition while NAC helps to overcome this limitation.