H +-mediated coupling of transmembrane Ca 2+ fluxes in vegetative Trichoderma viride mycelia suggested by the study of ageing and adaptation to extreme Ca 2+ concentrations

• Published in: Biochimica et biophysica acta. General subjects Vol. 1770; no. 1; pp. 99 - 105
• Main Authors: Ditte, Peter, Lakatoš, Boris, Varečka, L’udovít, Šimkovič, Martin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2007
• Subjects: 45Ca 2+ influx; Adaptation; Ageing; Proton-motive force; Trichoderma viride; Uncoupler; 45Ca 2+ influx; Trichoderma viride; Ageing; Proton-motive force; Uncoupler; Adaptation
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2006.07.013

The adaptation to extreme concentrations of Ca 2+ and its consequence on the properties of the 45Ca 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 45Ca 2+ influx but the adaptation to high [Ca 2+] o increased the K M(Ca2+). The V max of the 45Ca 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 μM), as compared to the control, whereas the Ca 2+ chelator, EGTA, stimulated it. In the aged mycelia, the stimulation by TCS of the 45Ca 2+ influx faded away, in parallel with the activity of the H +-ATPase. The 45Ca 2+ efflux from mycelia was affected by TCS in a similar way as the 45Ca 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.