Molecular bases of circadian magnesium rhythms across eukaryotes

Circadian clocks allow for the physiological anticipation of daily environmental changes. A circadian rhythm in intracellular Mg2+ was recently discovered in multiple eukaryotes. Given the pivotal role for Mg2+ in metabolism, Mg2+ rhythms could affect cellular energy expenditure over the daily cycle. To probe the potential mechanisms underlying the generation of cellular Mg2+ rhythms, we present a phylogenetic analysis of Mg2+ transport proteins. Extensive conservation was observed for ancestral prokaryotic proteins, identifying these as candidate proteins mediating Mg2+ rhythms across eukaryotes. We also posit that shared allosteric regulation of Mg2+ transport proteins might underlie Mg2+ rhythms and propose a reciprocal feedback model between the rhythmic usage of Mg2+ and rhythmic transport activity.