Abstract
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.
Highlights
The Target of Rapamycin Complex 1 (TORC1) involved in coordination of cell growth and metabolism is highly conserved among eukaryotes
To analyze TORC1 activation in yeast expressing a plant plasma-membrane H +-ATPase, we typically use a GAL1p-PMA1 pma2Δ strain, i.e. a strain where the PMA1 gene is placed under the control of the galactose-inducible, glucose-repressible GAL1 promoter and the PMA2 gene, encoding a second, poorly expressed H+-ATPase, is deleted
TORC1 is highly conserved among eukaryotes, the physiological signals and mechanisms controlling its activity, best studied in human cells, have obviously diverged among the major eukaryotic lineages
Summary
The Target of Rapamycin Complex 1 (TORC1) involved in coordination of cell growth and metabolism is highly conserved among eukaryotes. We have previously reported that in yeast, nutrient-uptake-coupled H+ influx elicits transient TORC1 activation and that the plasma-membrane H+-ATPase Pma[1] 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 Pma[1] in yeast, to promote H+-elicited TORC1 activation This H+-ATPase is highly similar to Pma[1] but has a longer carboxy-terminal tail binding 14–3–3 proteins. Upstream signals controlling mTORC1 (mechanistic or mammalian TORC1) in these cells include amino acids, nucleotides, growth factors, the energy status of the cell, and stress c onditions[1,2]. The only TORC1-controlling amino acid sensing system to have been characterized is the leucine-tRNA synthetase, which acts through regulation of G tr[19]
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