A plant plasma-membrane H⁺-ATPase promotes yeast TORC1 activation via its carboxy-terminal tail

The Target of Rapamycin Complex 1 (TORC1) involved in coordination of cell growth and metabolism is highly conserved among eukaryotes. Yet the signals and mechanisms controlling its activity differ among taxa, according to their biological specificities. A common feature of fungal and plant cells, distinguishing them from animal cells, is that their plasma membrane contains a highly abundant H⁺-ATPase which establishes an electrochemical H⁺ gradient driving active nutrient transport. We have previously reported that in yeast, nutrient-uptake-coupled H⁺ influx elicits transient TORC1 activation and that the plasma-membrane H⁺-ATPase Pma1 plays an important role in this activation, involving more than just establishment of the H⁺ gradient. We show here that the PMA2 H⁺-ATPase from the plant Nicotiana plumbaginifolia can substitute for Pma1 in yeast, to promote H⁺-elicited TORC1 activation. This H⁺-ATPase is highly similar to Pma1 but has a longer carboxy-terminal tail binding 14-3-3 proteins. We report that a C-terminally truncated PMA2, which remains fully active, fails to promote H⁺-elicited TORC1 activation. Activation is also impaired when binding of PMA2 to 14-3-3 s is hindered. Our results show that at least some plant plasma-membrane H⁺-ATPases share with yeast Pma1 the ability to promote TORC1 activation in yeast upon H⁺-coupled nutrient uptake.