Limitation of phosphate assimilation maintains cytoplasmic magnesium homeostasis

Roberto E. Bruna, Christopher G. Kendra, Eduardo A. Groisman, Mauricio H. Pontes

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Phosphorus (P) is an essential component of core biological molecules. In bacteria, P is acquired mainly as inorganic orthophosphate (Pi) and assimilated into adenosine triphosphate (ATP) in the cytoplasm. Although P is essential, excess cytosolic Pi hinders growth. We now report that bacteria limit Pi uptake to avoid disruption of Mg2+-dependent processes that result, in part, from Mg2+ chelation by ATP. We establish that the MgtC protein inhibits uptake of the ATP precursor Pi when Salmonella enterica serovar Typhimurium experiences cytoplasmic Mg2+ starvation. This response prevents ATP accumulation and overproduction of ribosomal RNA that together ultimately hinder bacterial growth and result in loss of viability. Even when cytoplasmic Mg2+ is not limiting, excessive Pi uptake increases ATP synthesis, depletes free cytoplasmic Mg2+, inhibits protein synthesis, and hinders growth. Our results provide a framework to understand the molecular basis for Pi toxicity. Furthermore, they suggest a regulatory logic that governs P assimilation based on its intimate connection to cytoplasmic Mg2+ homeostasis.

Original languageEnglish (US)
Article numbere2021370118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number11
StatePublished - Mar 11 2021

All Science Journal Classification (ASJC) codes

  • General


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