Upregulation of vacuolar H+-translocating pyrophosphatase by phosphate starvation of Brassica napus (rapeseed) suspension cell cultures

The influence of phosphate (Pi) deprivation on the vacuolar H+-translocatin g pyrophosphatase (PPiase) and ATPase in tonoplast vesicles from Brassica n apus suspension cells was assessed. Pi starvation significantly elevated th e ratios of PPi-: ATP-dependent H+ translocation rate and H+-PPiase: H+-ATP ase hydrolytic activities. These increases were reversed 36 h following res upply of 2.5 mM Pi to the Pi-starved cells. Immunoblotting indicated that P i starvation also induced a two-fold increase in the amount of H+-PPiase pr otein, whereas the amount of H+-ATPase remained unchanged. It is proposed t hat H+-PPiase facilitates the conservation of limited ATP pools, and Pi rec ycling during Pi stress. (C) 2000 Federation of European Biochemical Societ ies. Published by Elsevier Science B.V. All rights reserved.