FeS protein levels in Arabidopsis plants expressing a mutated NEET protein

Iron-sulfur (Fe-S) clusters play an essential role in plants as protein co-factors mediating diverse electron transfer reactions. Because they can react with oxygen to form reactive oxygen species (ROS) and cause cellular damage, the biogenesis of Fe-S clusters is highly regulated. A newly discovered group of 2Fe-2S proteins, termed NEET proteins, was recently proposed to coordinate iron-sulfur, iron, and ROS homeostasis in mammalian cells. Here we report that disrupting the function of AtNEET, the sole member of the NEET protein family in Arabidopsis thaliana, triggers a leaf-associated Fe- and Fe-S-deficiency responses, iron overload in chloroplasts (1.2-1.5 fold), chlorosis, structural damage to chloroplasts, and a high seedling mortality rate. Our findings suggest that disrupting AtNEET function disrupts the transfer of 2Fe-2S clusters from the chloroplastic 2Fe-2S biogenesis pathway to Fe-S proteins, and that uncoupling this process triggers a leaf-associated Fe-deficiency response that results in iron overload in chloroplasts and enhanced ROS accumulation