H+-mediated coupling of transmembrane Ca2+ fluxes in vegetative Trichoderma viride mycelia suggested by the study of ageing and adaptation to extreme Ca2+ concentrations

• Published in: Biochimica et biophysica acta Vol. 1770; no. 1; pp. 99 - 105
• Main Authors: Ditte, Peter, Lakatoš, Boris, Varečka, L’udovít, Šimkovič, Martin
• Format: Journal Article
• Language: English
• Published: Netherlands 01.01.2007
• Subjects: Calcium - metabolism; Cell Membrane - enzymology; Cell Membrane - metabolism; Ion Transport; Proton-Translocating ATPases - metabolism; Protons; Trichoderma - metabolism
• ISSN: 0304-4165; 0006-3002
• DOI: 10.1016/j.bbagen.2006.07.013

The adaptation to extreme concentrations of Ca(2+) and its consequence on the properties of the (45)Ca(2+) transport were studied in submerged mycelia of Trichoderma viride. The adaptation to low [Ca(2+)](o) did not cause changes in kinetic parameters of the (45)Ca(2+) influx but the adaptation to high [Ca(2+)](o) increased the K(M(Ca2+)). The V(max) of the (45)Ca(2+) influx decreased with the age of (non-adapted) mycelia with concomitant decrease of the K(M(Ca2+)) these changes were prevented in mycelia adapted to high Ca(2+). High [Ca(2+)](o) decreased the stimulation by the uncoupler, 3, 3', 4', 5-tetrachloro salicylanilide (TCS) (30 muM), as compared to the control, whereas the Ca(2+) chelator, EGTA, stimulated it. In the aged mycelia, the stimulation by TCS of the (45)Ca(2+) influx faded away, in parallel with the activity of the H(+)-ATPase. The (45)Ca(2+) efflux from mycelia was affected by TCS in a similar way as the (45)Ca(2+) influx. The results demonstrate the adaptive responses of transport processes participating in the mycelial Ca(2+) homeostasis and ageing are in agreement with a notion that both Ca(2+)-influx and-efflux are coupled by the H(+)-homeostasis at the plasma membrane.