# Molecular bases of circadian magnesium rhythms across eukaryotes

## TL;DR

This paper explores how magnesium levels in cells follow daily rhythms and suggests ancient transport proteins might control these rhythms.

## Contribution

The paper proposes that ancestral prokaryotic Mg2+ transport proteins and a feedback model could explain circadian magnesium rhythms in eukaryotes.

## Key findings

- Circadian rhythms in intracellular Mg2+ exist across eukaryotic kingdoms.
- Ancestral prokaryotic Mg2+ transport proteins are conserved and may mediate Mg2+ rhythms.
- A reciprocal feedback model between Mg2+ usage and transport activity is proposed.

## Abstract

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.

Circadian rhythms in intracellular [Mg2+] exist across eukaryotic kingdoms. Central roles for Mg2+ in metabolism suggest that Mg2
+ rhythms could regulate daily cellular energy and metabolism. In this Perspective paper, we propose that ancestral prokaryotic transport proteins could be responsible for mediating Mg2+ rhythms and posit a feedback model between rhythmic usage of Mg2+ and rhythmic transport activity.