Dynamic calcium-mediated stress response and recovery signatures in the fungal pathogen, Candida albicans

Giuraniuc, C. V.; Parkin, C.; Cruz Almeida, M.; Fricker, M.; Shadmani, P.; Nye, S.; Wehmeier, S.; Chawla, S.; Bedekovic, T.; Lehtovirta-Morley, L.; Richards, D.; Gow, N. A. R.; Brand, A. C.

doi:10.1101/2023.04.20.537637

bioRxiv · 10.1101/2023.04.20.537637

Dynamic calcium-mediated stress response and recovery signatures in the fungal pathogen, Candida albicans

Giuraniuc, C. V.·Parkin, C.·Cruz Almeida, M.·Fricker, M.·Shadmani, P.·Nye, S.·Wehmeier, S.·Chawla, S.·Bedekovic, T.·Lehtovirta-Morley, L.·Richards, D.·Gow, N. A. R.·Brand, A. C.

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Abstract

Calcium (Ca2+) is an important second messenger for activating stress response signalling and cell adaptation in eukaryotic cells yet intracellular Ca2+-dynamics in fungi is poorly understood due to lack of effective real-time Ca2+ reporters. We engineered the GCaMP6f construct for use in the fungal pathogen, Candida albicans, and used live-cell imaging to observe dynamic Ca2+ spiking as well as slower changes in ambient Ca2+-GCaMP levels elicited by stress or gene deletion. Short-term exposure to membrane, osmotic or oxidative stress generated immediate stress-specific responses and repeated exposure revealed differential recovery signatures. Osmotic stress caused yeast cell shrinkage and no adaptation response, where Ca2+-GCaMP spiking was inhibited by 1 M NaCl but not by 0.66 M CaCl2. Treatment with SDS caused a spike-burst, raised ambient Ca2+-GCaMP levels and significant cell death, but surviving cells adapted over subsequent exposures. Treatment with 5 mM H2O2 abolished spiking and caused transient autofluorescence but cells adapted such that spiking returned and autofluorescence diminished on repeated exposure. Adaptation to H2O2 was dependent on Cap1, extracellular Ca2+ and calcineurin, but not on its downstream target, Crz1. Ca2+-dynamics were not affected by H2O2 in the hog1{Delta} or yvc1{Delta} mutants, suggesting a pre-adapted, resistant state, possibly due to changes in membrane permeability. Live-cell imaging of Ca2+-GCaMP responses in individual cells has therefore revealed the dynamics of Ca2+-influx, signalling and homeostasis and their role in the temporal stress response signatures of C. albicans.

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Giuraniuc, C. V., Parkin, C., Cruz Almeida, M., Fricker, M., Shadmani, P., Nye, S., Wehmeier, S., Chawla, S., Bedekovic, T., Lehtovirta-Morley, L., Richards, D., Gow, N. A. R., Brand, A. C.. 2023-04-20. Dynamic calcium-mediated stress response and recovery signatures in the fungal pathogen, Candida albicans. https://doi.org/10.1101/2023.04.20.537637

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