Contributions of the PMC1, VCX1 and YVC1 pathways to cytosolic calcium in response to pheromone

TARKOWSKI, NAHUEL; AGUILAR, PABLO S.; DAWSON, SILVINA PONCE

Paraná

Congreso; 54th Annual Meeting Argentine Society for Biochemistry and Molecular; 2018

Saccharomyces cerevisiae haploid cells secrete mating pheromones that indicatethe presence of cells of one mating type to those of the opposite mating type. This initiates a sequence of events, which includes cellular arrest and growth polarization towards the secretory cell. Studies showed that the incorporation of calcium is necessary for cell survival and signal transduction to coordinate the genes involved. Studying the dynamics of calcium using microscopy and the fluorescent sensor GCaMP6f we found that pheromone does not generate a single elevation of cytosolic ca2+ levels but transient increases in the form of bursts. Our results suggest that the information transmitted by calcium is encoded in the temporal distribution of these bursts. Calcium uptake depends on at least two pathways, system HACS and system LACS. Through genetic mutations, we eliminated the activity of these pathways and we were able to observe the dependence with the temporal distributions of calcium bursts. We have proposed that the calcium response not only depends on transport pathways from the extracellular medium, but it can also depend on each of the different calcium flow pathways to and from each of the internal reservoirs. The aim of this work isto define the role of calcium transporters in internal reservoirs in response to pheromone. To address this, we monitored cells with mutated vacuolar Ca2+ ATPase (pmc1Δ), cell with mutated vacuolar membrane antiporter with Ca2+/H+ (vcx1Δ) and cell with mutated vacuolar channel (yvc1Δ). We are currently studying the variation of calcium burst distributions by eliminating the activity of these pathways through genetic mutations.