Change in inorganic phosphate physical state can regulate transcription

摘要

Inorganic phosphate (P,), a ubiquitous metabolite, is involved in all major biochemical pathways. We demonstrate that, in vitro, MgHP04 (the intracellular P, form) at physiological concentrations can exist in a metastable supersaturated dissolved state or as a precipitate. We have shown that in solution, MgHP04 strongly stimulates exonuclease nascent transcript cleavage by RNA polymerase. We report here that MgHP04 precipitate selectively and efficiently inhibits transcription initiation in vitro. Inview of the MgHP04 solubility and in vitro sensitivity of RNA synthesis to MgHP04 precipitate, at physiological concentrations, MgHP04 should cause a 50-98% inhibition of cellular RNA synthesis, thus exerting a strong regulatory action. The effects of P, on transcription in vivo will, therefore, reflect the physical state of intracellular P,.