Reversible redox control of plant vacuolar H+–ATPase activity is related to disulfide bridge formation in subunit E as well as subunit A.

Autor: Tavakoli, Nastaran, Kluge, Christoph, Golldack, Dortje, Mimura, Tetsuro, Dietz, Karl-Josef
Předmět:
Zdroj: Plant Journal; Oct2001, Vol. 28 Issue 1, p51-59, 9p, 4 Diagrams, 5 Graphs, 1 Map
Abstrakt: SummaryThe plant vacuolar proton pump can be subjected to reversible redox regulation in vitro. The redox-dependent activity change involves disulfide bridge formation not only in Vatp A, as reported for bovine V–ATPase, but also in the stalk subunit Vatp E. Microsomal membranes isolated from barley leaves were analysed for their activity of bafilomycin-sensitive ATP hydrolysis and proton pumping using quinacrine fluorescence quenching in vesicle preparations. ATP hydrolysis and proton pumping activity were inhibited by H2O2. H2O2-deactivated ATPase was reactivated by cysteine and glutathione. The glutathione concentration needed for half maximal reactivation was 1 mmol l-1. The activity loss was accompanied by shifts in electrophoretic mobility of Vatp A and E which were reversed upon reductive reactivation. The redox-dependent shift was also seen with recombinant Vatp E, and was absent following site-directed mutagenesis of either of the two cys residues conserved throughout all plant Vatp E sequences. V–ATPase was also inhibited by oxidized thioredoxin. These results support the hypothesis that tuning of vacuolar ATPase activity can be mediated by redox control depending on the metabolic requirements. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
Externí odkaz: