Starvation in Yeasts: Biochemical Aspects pp. 103-150
Authors: (Halyna M. Semchyshyn, Maria M. Bayliak, Volodymyr I. Lushchak, Department of Biochemistry, Vassyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine)
Abstract: Like other microorganisms, yeast Saccharomyces cerevisiae respond to starvation by entering stationary phase. During stationary phase yeast cells undergo changes in transcription and translation activities that result in a dramatic number of physiological and biochemical transformations detailed in this review. Several nutrient-responsive signalling pathways were found to play overlapping regulatory roles in the yeast survival under starvation conditions. The main nutrient-regulated signalling pathways and protein kinases such as Snf1p/AMP-activated kinase, TOR, Sch9, PKA, MAP are described here. Stationary-phase yeast culture is considered as a good model system for aging, autophagy and apoptosis of somatic cells of higher eukaryotic organisms, as both are postmitotic cells and depend on mitochondrial respiration to maintain viability. In stationary-phase yeast culture, reactive oxygen species produced during respiratory metabolism cause cumulative oxidative damage to almost all cellular components leading to aging and cell death. In this context an important role of antioxidant defence in nutrient-mediated lifespan extension of stationary phase yeast cells is discussed. Special attention is paid to the beneficial effects of calorie restriction (a variant of partial starvation) on the lifespan and prevention of oxidative damage in yeast during stationary phase.