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.

• PMID: 11519685
• PubMed
• PubTator

Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Simkovic M, Lakatos B, Tsuji FI, Muto S, Varecka L

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