High-Affinity Plasma Membrane Ca²⁺ Channel Cch1 Modulates Adaptation to Sodium Dodecyl Sulfate-Triggered Rise in...

The cytosolic calcium concentration ([Ca²⁺]_cyt) in yeast cells is maintained at a low level via the action of different transporters sequestrating these cations in the vacuole. Among them, the vacuolar Ca²⁺ ATPase Pmc1 crucially contributes to this process. Its inactivation in Ogataea yeasts was shown to cause sodium dodecyl sulfate (SDS) hypersensitivity that can be alleviated by the inactivation of the plasma membrane high-affinity Ca²⁺ channel Cch1. Here, we show that SDS at low concentrations induces a rapid influx of external Ca²⁺ into cells, while the plasma membrane remains impermeable for propidium iodide. The inactivation of Pmc1 disturbs efficient adaptation to this activity of SDS. The inactivation of Cch1 partially restores the ability of pmc1 mutant cells to cope with an increased [Ca²⁺]_cyt that correlates with the suppression of SDS hypersensitivity. At the same time, Cch1 is unlikely to be directly involved in SDS-induced Ca²⁺ influx, since its inactivation does not decrease the amplitude of the rapid [Ca²⁺]_cyt elevation in the pmc1-Δ mutant. The obtained data suggest that the effects of CCH1 inactivation on SDS sensitivity and coping with increased [Ca²⁺]_cyt are related to an additional Cch1 function beyond its direct involvement in Ca²⁺ transport.