Expression of a dominant‐negative AtNEET‐H89C protein disrupts iron–sulfur metabolism and iron homeostasis in Arabidopsis

Abstract

Summary Iron–sulfur (Fe–S) clusters play an essential role in plants as protein cofactors mediating diverse electron transfer reactions. Because they can react with oxygen to form reactive oxygen species (ROS) and inflict cellular damage, the biogenesis of Fe–S clusters is highly regulated. A recently discovered group of 2Fe–2S proteins, termed NEET proteins, was proposed to coordinate Fe–S, Fe 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 leaf‐associated Fe–S‐ and Fe‐deficiency responses, elevated Fe content 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 different cytosolic and chloroplastic Fe–S proteins, as well as to the cytosolic Fe–S biogenesis system, and that uncoupling this process triggers leaf‐associated Fe–S‐ and Fe‐deficiency responses that result in Fe over‐accumulation in chloroplasts and enhanced ROS accumulation. We further show that AtNEET transfers its 2Fe–2S clusters to DRE2, a key protein of the cytosolic Fe–S biogenesis system, and propose that the availability of 2Fe–2S clusters in the chloroplast and cytosol is linked to Fe homeostasis in plants.

Jasmonic Acid Is Required for Plant Acclimation to a Combination of High Light and Heat Stress

“…Leaves of Col plants subjected to the different stress treatments were analyzed by TEM as described in Zandalinas et al (2019b). Briefly, leaves were fixed in 2% (w/v) paraformaldehyde and 2% (w/v) glutaraldehyde in 100 mM of sodium cacodylate buffer at pH 7.35.…”

The developmental and iron nutritional pattern of PIC1 and NiCo does not support their interdependent and exclusive collaboration in chloroplast iron transport in Brassica napus

“…In Arabidopsis thaliana, NEET was very recently also pointed out as a possible key regulator of Fe metabolism in chloroplasts. Disruption in the function of NEET results in an uncoupling in the transfer of chloroplast-synthetized Fe 2 S 2 cluster to cytosolic proteins as well as in an accumulation of Fe in chloroplasts (Zandalinas et al 2019). In our measurements, limited Fe accumulation in chloroplasts initially induced the Fe uptake machinery, but reaching leaf maturity acted as a repressor of BnPIC1 transcription.…”

“…Since under Fe deficiency, the expression of TAP1, a hypothetical chloroplast Fe-S cluster exporter, was previously shown to be upregulated in parallel to MAR1 (Yang et al 2010), remodelling of Fe content not only covers the export of Fe (complexes) but also Fe-containing cofactors. On the other hand, neither the overexpression of H89C or NEET, having profound roles in the Fe 2 S 2 cluster incorporation and Fe sensing in chloroplasts, induced any significant changes in the expression of neither MAR1, nor PIC1 (Zandalinas et al 2019). In addition, based on an autophagy mutant atg5-1 where decomposing of chloroplasts is affected, retranslocation of Fe strongly decreases from vegetative tissues (Mari et al 2020).…”

Cadmium interference with iron sensing reveals transcriptional programs sensitive and insensitive to reactive oxygen species

“…AtNEET to the holo-Fd peak (Fig 7b, inset; (Zandalinas et al, 2019)). Notably, the efficiency of this transfer was impaired by Cd (Fig 7b) and quantification of the absorbances at each characteristic peak showed significant decreases in the Fe-S transfer efficiency at Cd concentrations as low as 5 µM Cd (Fig 7c).…”