Hsp90 and metal‐binding J‐protein family chaperones are not critically involved in cellular iron–sulfur protein assembly and iron regulation in yeast

Abstract

Systematic studies have revealed interactions between components of the Hsp90 chaperone system and Fe/S protein biogenesis or iron regulation. In addition, two chloroplast‐localized DnaJ‐like proteins, DJA5 and DJA6, function as specific iron donors in plastidial Fe/S protein biogenesis. Here, we used Saccharomyces cerevisiae to study the impact of both the Hsp90 chaperone and the yeast DJA5‐DJA6 homologs, the essential cytosolic Ydj1, and the mitochondrial Mdj1, on cellular iron‐related processes. Despite severe phenotypes induced upon depletion of these crucial proteins, there was no critical in vivo impact on Fe/S protein biogenesis or iron regulation. Importantly, unlike the plant DJA5‐DJA6 iron chaperones, Ydj1 and Mdj1 did not bind iron in vivo, suggesting that these proteins use zinc for function under normal physiological conditions.