Abstract
Circadian clocks allow for the physiological anticipation of daily environmental changes. A circadian rhythm in intracellular Mg(2+) was recently discovered in multiple eukaryotes. Given the pivotal role for Mg(2+) in metabolism, Mg(2+) rhythms could affect cellular energy expenditure over the daily cycle. To probe the potential mechanisms underlying the generation of cellular Mg(2+) rhythms, we present a phylogenetic analysis of Mg(2+) transport proteins. Extensive conservation was observed for ancestral prokaryotic proteins, identifying these as candidate proteins mediating Mg(2+) rhythms across eukaryotes. We also posit that shared allosteric regulation of Mg(2+) transport proteins might underlie Mg(2+) rhythms and propose a reciprocal feedback model between the rhythmic usage of Mg(2+) and rhythmic transport activity.