Ferrous iron uptake via IRT1/ZIP evolved at least twice in green plants

Abstract

Summary Iron (Fe) is essential for virtually all organisms, being irreplaceable because of its electrochemical properties that enable many biochemical processes, including photosynthesis. Besides its abundance, Fe is generally found in the poorly soluble form of ferric iron (Fe3+), while most plants uptake the soluble form Fe2+. The model angiosperm Arabidopsis thaliana, for example, captures Fe through a mechanism that lowers rhizosphere pH through proton pumping that increases Fe3+ solubility, which is then reduced by a membrane‐bound reductase and transported into the cell by the zinc‐regulated, iron‐regulated transporter‐like protein (ZIP) family protein AtIRT1. ZIP proteins are transmembrane transporters of divalent metals such as Fe2+, Zn2+, Mn2+, and Cd2+. In this work, we investigated the evolution of functional homologs of IRON‐REGULATED TRANSPORTER 1/ZIP in the supergroup Archaeplastida (Viridiplantae + Rhodophyta + Glaucophyta) using 51 genomes of diverse lineages. Our analyses suggest that Fe is acquired through deeply divergent ZIP proteins in land plants and chlorophyte green algae, indicating that Fe2+ uptake by ZIP proteins evolved independently at least twice throughout green plant evolution. Our results indicate that the archetypical IRON‐REGULATED TRANSPORTER (IRT) proteins from angiosperms likely emerged before the origin of land plants during early streptophyte algae terrestrialization, a process that required the evolution of Fe acquisition in terrestrial subaerial settings.

Manganese‐dependent transcription regulation by MntR and PerR in Thermus thermophilusHB8

“…ZIP transporters typically facilitate the import of zinc, iron, or manganese ions. While metal specificity can be promiscuous, there are instances of metal ion preference for ZIP proteins (Puccio et al., 2022; Rodrigues et al., 2023). When aligning the Zip1 amino acid sequence to other ZIP homologs, we identified conserved metal binding residues that were identical to Mn 2+ ‐specific ZIP transporters (Figure S5).…”