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Intracellular reception and signaling of phosphate
Cells face a phosphate challenge. Growth requires a minimal concentration of this limiting resource because intracellular phosphate (Pi) is a compound of nucleic acids and modifies most cellular proteins. At the same time, cytosolic Pi may not rise much, because elevated cytosolic Pi can stall metabolism. It reduces the free energy that nucleotide triphosphate hydrolysis can provide to drive energetically unfavorable reactions.
Our group tries to elucidate how cells strike this critical balance. We characterize a novel pathway for intracellular phosphate reception and signaling (INPHORS), which may regulate cytosolic Pi homeostasis by coordinating multiple SPX-domain-containing proteins for import and export of Pi, and for Pi storage in acidocalcisomes. Acidocalcisomes are conserved but very poorly understood organelles. We propose that their role in buffering cytosolic Pi concentration is one reason for their evolutionary conservation.
