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The effect of azalomycin F on Ca2+ homeostasis in Trichoderma viride and Saccharomyces cerevisiae
M Simkovic1, B Lakatos, F I Tsuji
1Department of Biochemistry and Microbiology, Slovak University of Technology, Bratislava.
Abstract:
Azalomycin F (AMF), a macrocyclic lactone antibiotic, in concentrations of 10(-5) g/ml (10(-6) - 10(-5) mol/l) was found to stimulate both the 45Ca2+ influx and efflux in intact Trichoderma viride submerged mycelium and in cells of Saccharomyces cerevisiae without having Ca2+ ionophoric properties. AMF also inhibited ATP-dependent Ca2+ uptake in membrane fractions prepared from T. viride submerged mycelium. 45Ca2+ which had been accumulated in membrane fractions in an ATP-dependent manner was released upon addition of AMF. This release was observed in light organellar fractions (LOF) of S. cerevisiae and of T. viride submerged mycelium and, to a small extent, in heavy organellar fraction (HOF) of S. cerevisiae. No Ca2+ releasing effect of AMF was observed in HOF from T. viride submerged mycelium. In S. cerevisiae expressing Ca2+-dependent photoprotein aequorin, AMF induced transients of luminescence which reflect changes in the cytoplasmic Ca2+ concentration. The results suggest that the stimulation by AMF of the Ca2+ efflux from the mycelium (cells) could be explained by an increase of the cytoplasmic Ca2+ concentration due to the release of Ca2+ from microsomal membranes or to the stimulation of Ca2+ influx.
Insights
Azalomycin F (AMF) stimulates calcium (Ca2+) movement in fungi and yeast cells. This antibiotic affects Ca2+ influx and efflux, potentially by influencing intracellular Ca2+ levels.
Area of Science:
- Biochemistry
- Mycology
- Cell Biology
Background:
- Calcium ions (Ca2+) are crucial for various cellular processes in fungi and yeast.
- Understanding how external compounds affect intracellular calcium homeostasis is vital for cell biology.
- Azalomycin F (AMF) is a macrocyclic lactone antibiotic with potential cellular effects.
Purpose of the Study:
- To investigate the effects of Azalomycin F (AMF) on calcium (Ca2+) transport in Trichoderma viride and Saccharomyces cerevisiae.
- To determine if AMF possesses Ca2+ ionophoric properties.
- To elucidate the mechanisms by which AMF influences Ca2+ homeostasis in these organisms.
Main Methods:
- Utilized 45Ca2+ tracer to measure Ca2+ influx and efflux in intact fungal mycelium and yeast cells.
- Examined ATP-dependent Ca2+ uptake and release in isolated membrane fractions.
- Employed aequorin luminescence assay in S. cerevisiae to monitor cytoplasmic Ca2+ concentration changes.
Main Results:
- AMF (10^-5 g/ml) stimulated both 45Ca2+ influx and efflux in T. viride and S. cerevisiae without acting as a Ca2+ ionophore.
- AMF inhibited ATP-dependent Ca2+ uptake in T. viride membrane fractions and induced Ca2+ release from light organellar fractions (LOF) of both species.
- AMF triggered luminescence transients in aequorin-expressing S. cerevisiae, indicating alterations in cytoplasmic Ca2+ levels.
Conclusions:
- AMF modulates Ca2+ transport in fungi and yeast, affecting both influx and efflux pathways.
- The observed effects suggest AMF may increase cytoplasmic Ca2+ by releasing it from intracellular stores (microsomal membranes) or enhancing influx.
- AMF's impact on Ca2+ homeostasis warrants further investigation into its broader cellular and physiological consequences.
