Simulating calcium influx and free calcium concentrations in yeast

作者：Cui Jiangjun; Kaandorp Jaap A^*; Ositelu Olufisayo O; Beaudry Veronica; Knight Alicia; Nanfack Yves F; Cunningham Kyle W

来源：Cell Calcium, 2009, 45(2): 123-132.

DOI：10.1016/j.ceca.2008.07.005

• Calcium homeostasis
• Calcium signaling
• Response curve
• Competitive inhibition

Yeast can proliferate in environments containing very high Ca(2 ) primarily due to the activity of vacuolar Ca(2 ) transporters Pmc1 and Vcx1. Yeast mutants lacking these transporters fail to grow in high Ca(2 ) environments, but growth can be restored by small increases in environmental Mg(2 ). Low extracellular Mg(2 ) appeared to competitively inhibit novel Ca(2 ) influx pathways and to diminish the concentration of free Ca(2 ) in the cytoplasm, as judged from the luminescence of the photoprotein aequorin. These Mg(2 )-sensitive Ca(2 ) influx pathways persisted in yvc1 cch1 double mutants. Based on mathematical models of the aequorin luminescence traces, we propose the existence in yeast of at least two Ca(2 ) transporters that undergo rapid feedback inhibition in response to elevated cytosolic free Ca(2 ) concentration. Finally, we show that Vcx1 helps return cytosolic Ca(2 ) toward resting levels after shock with high extracellular Ca(2 ) much more effectively than Pmc1 and that calcineurin, a protein phosphatase regulator of Vcx1 and Pmc1, had no detectable effects on these factors within the first few minutes of its activation. Therefore, computational modeling of Ca(2 ) transport and signaling in yeast can provide important insights into the dynamics of this complex system.

• 出版日期2009-2