Mitochondrial functions in yeast S. Cerevisiae with different resistance to anhydrobiosis

Abstract

Anabiosis is a unique natural phenomenon of temporary reversible delay of metabolism by live organisms upon untoward conditions. Yeasts are a great model for investigation of the survival mechanism in anhydrobiosis because these cells are well explored and can undergo multiple cycles of dehydration and subsequent rehydration. Practically all intracellular structures are subjected to changes during the dehydration and subsequent rehydration-reactivation of yeasts. It is believed that the ability of mitochondria to start the transformation of energy at the early beginning of the reactivation stage is necessary for the repair of damaged intracellular structures and macromolecules. The aim of this study was to investigate mitochondrial functions of two closely related strains of yeast S. cerevisiae – moderately resistant strain to dehydration #14 and very resistant strain to dehydration - #77, also its mutants, lacking fusion-fission genes functionality (Δfzo1, Δdnm1, Δdnm1/Δfzo1) and wild type yeast WT303-a1. Isolation of mitochondria from yeast was achieved using modified Meisinger et al. protocol. Mitochondrial functions were evaluated by oxygen consumption (respiratory rate) at different metabolic states (State 2 (LEAK), State 3, maximum oxidative phosphorylation (OXPHOS), OXPHOS via complex IV). Results revealed that maximum respiration intensity was observed in #14 strain which is highly resistant to dehydration, lower respiratory rate was observed in #77 strain. #14 LEAK value was considerably high, nevertheless it was not a sign of damaged mitochondrial membrane, because RCI (State 3/LEAK respiratory rate ratio) value was 2. Although oxygen flow through IV respiratory chain complex in WT303-a1, Δdnm1 and #77 mitochondria was similar, however State 3 and OXPHOS values were significantly different. Yeast mitochondria with fusion-fission gene mutations in all conditions showed the lowest values of respiratory rate. [...]