Molecular Mechanisms Controlling Phosphate-Induced Downregulation of the Yeast Pho84 Phosphate Transporter

Lundh, Fredrik; Mouillon, Jean‐Marie; Samyn, Dieter R.; Stadler, Kent; Popova, Yulia; Lagerstedt, Jens O.; Thevelein, Johan M.; Persson, Bengt L.

doi:10.1021/bi9001198

Cited by 50 publications

(36 citation statements)

References 46 publications

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“…It occurs through endocytosis followed by routing to degradation at lytic vacuoles. A similar regulatory event is observed in yeast but appears to rely on a different mechanism (Lundh et al, 2009).…”

Section: Model Of Pht1 Regulationsmentioning

confidence: 54%

“…A similar endocytosis mechanism that is followed by vacuolar breakdown has been identified in yeast for the PHT1 homolog PHO84 (Lundh et al, 2009). Interestingly, despite the high conservation between plant and yeast Pi transporters, the sequence identified in the central loop of PHO84 (amino acids 304 to 327), which is required for this regulation, appears to be deleted in all PHT1 members.…”

Section: Specific Degradation Of Plasma Membrane Pht1 In the Presencementioning

confidence: 58%

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Arabidopsis thaliana High-Affinity Phosphate Transporters Exhibit Multiple Levels of Posttranslational Regulation

et al. 2011

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In Arabidopsis thaliana, the PHOSPHATE TRANSPORTER1 (PHT1) family encodes the high-affinity phosphate transporters. They are transcriptionally induced by phosphate starvation and require PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR (PHF1) to exit the endoplasmic reticulum (ER), indicating intracellular traffic as an additional level of regulation of PHT1 activity. Our study revealed that PHF1 acts on PHT1, upstream of vesicle coat protein COPII formation, and that additional regulatory events occur during PHT1 trafficking and determine its ER exit and plasma membrane stability. Phosphoproteomic and mutagenesis analyses revealed modulation of PHT1;1 ER export by Ser-514 phosphorylation status. Confocal microscopy analysis of root tip cells showed that PHT1;1 is localized to the plasma membrane and is present in intracellular endocytic compartments. More precisely, PHT1;1 was localized to sorting endosomes associated with prevacuolar compartments. Kinetic analysis of PHT1;1 stability and targeting suggested a modulation of PHT1 internalization from the plasma membrane to the endosomes, followed by either subsequent recycling (in low Pi) or vacuolar degradation (in high Pi). For the latter condition, we identified a rapid mechanism that reduces the pool of PHT1 proteins present at the plasma membrane. This mechanism is regulated by the Pi concentration in the medium and appears to be independent of degradation mechanisms potentially regulated by the PHO2 ubiquitin conjugase. We propose a model for differential trafficking of PHT1 to the plasma membrane or vacuole as a function of phosphate concentration.

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Section: Model Of Pht1 Regulationsmentioning

confidence: 54%

Section: Specific Degradation Of Plasma Membrane Pht1 In the Presencementioning

confidence: 58%

Arabidopsis thaliana High-Affinity Phosphate Transporters Exhibit Multiple Levels of Posttranslational Regulation

et al. 2011

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“…Although P i availability appears to be the major signal, recent studies have revealed novel components in the regulatory circuit of the PHO responses. It has been shown that, after prolonged P i starvation, the repletion of P i to cells leads to degradation of the high affinity phosphate transporter Pho84 (53,54). This response requires the activation of the protein kinase A (53,54), demonstrating a connection between the glucose and phosphate signaling pathways.…”

Section: Discussionmentioning

confidence: 99%

“…It has been shown that, after prolonged P i starvation, the repletion of P i to cells leads to degradation of the high affinity phosphate transporter Pho84 (53,54). This response requires the activation of the protein kinase A (53,54), demonstrating a connection between the glucose and phosphate signaling pathways. The level of other nutrient intermediates also influences the activation of the PHO pathway.…”

Section: Discussionmentioning

confidence: 99%

Phosphate-responsive Signaling Pathway Is a Novel Component of NAD+ Metabolism in Saccharomyces cerevisiae

Lin

2011

Journal of Biological Chemistry

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Nicotinamide adenine dinucleotide (NADNAD ϩ and its reduced form NADH are essential pyridine nucleotides mediating redox reactions in cellular metabolism. In addition, NAD ϩ is an essential substrate in several protein modification reactions, in particular sirtuin-mediated protein deacetylation and the addition of ADP-ribose moieties. These modifications are essential for the proteins functioning in Ca 2ϩ

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“…Addition of phosphate also triggers phosphorylation and ubiquitination of Pho84 followed by endocytic internalization and degradation in the vacuole. This process may be triggered by Pho84-mediated activation of the PKA pathway (17).…”

mentioning

confidence: 99%

Transport and signaling through the phosphate-binding site of the yeast Pho84 phosphate transceptor

Popova

Palvannan

Lonati

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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138

132

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A novel concept in eukaryotic signal transduction is the use of nutrient transporters and closely related proteins as nutrient sensors. The action mechanism of these “transceptors” is unclear. The Pho84 phosphate transceptor in yeast transports phosphate and mediates rapid phosphate activation of the protein kinase A (PKA) pathway during growth induction. We have now identified several phosphate-containing compounds that act as nontransported signaling agonists of Pho84. This indicates that signaling does not require complete transport of the substrate. For the nontransported agonist glycerol-3-phosphate (Gly3P), we show that it is transported by two other carriers, Git1 and Pho91, without triggering signaling. Gly3P is a competitive inhibitor of transport through Pho84, indicating direct interaction with its phosphate-binding site. We also identified phosphonoacetic acid as a competitive inhibitor of transport without agonist function for signaling. This indicates that binding of a compound into the phosphate-binding site of Pho84 is not enough to trigger signaling. Apparently, signaling requires a specific conformational change that may be part of, but does not require, the complete transport cycle. Using Substituted Cysteine Accessibility Method (SCAM) we identified Phe 160 in TMD IV and Val 392 in TMD VIII as residues exposed with their side chain into the phosphate-binding site of Pho84. Inhibition of both transport and signaling by covalent modification of Pho84 F160C or Pho84 V392C showed that the same binding site is used for transport of phosphate and for signaling with both phosphate and Gly3P. Our results provide to the best of our knowledge the first insight into the molecular mechanism of a phosphate transceptor.

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Molecular Mechanisms Controlling Phosphate-Induced Downregulation of the Yeast Pho84 Phosphate Transporter

Cited by 50 publications

References 46 publications

Arabidopsis thaliana High-Affinity Phosphate Transporters Exhibit Multiple Levels of Posttranslational Regulation

Arabidopsis thaliana High-Affinity Phosphate Transporters Exhibit Multiple Levels of Posttranslational Regulation

Phosphate-responsive Signaling Pathway Is a Novel Component of NAD+ Metabolism in Saccharomyces cerevisiae

Transport and signaling through the phosphate-binding site of the yeast Pho84 phosphate transceptor

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