Glutathione regulates transcriptional activation of iron transporters via S‐nitrosylation of bHLH factors to modulate subcellular iron homoeostasis. (18th April 2022)

• Record Type: Journal Article
• Authors: Shee, Ranjana; Ghosh, Soumi; Khan, Pinki; Sahid, Salman; Roy, Chandan; Shee, Dibyendu; Paul, Soumitra; Datta, Riddhi
• Is Part Of: Plant, cell and environment. Volume 45:Number 7(2022)
• Page Start: 2176
• Page End: 2190
• Publication Date: 2022-04-18
• Subjects: GSNO -- iron deficiency -- NRAMP -- PIC; Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.14331
• Languages: English
• ISSNs: 0140-7791

Abstract

Abstract: Glutathione (GSH) is known to regulate iron (Fe) deficiency response in plants but its involvement in modulating subcellular Fe homoeostasis remains elusive. In this study, we report that the GSH‐deficient mutants, cad2‐1 and pad2‐1 displayed increased sensitivity to Fe deficiency with significant downregulation of the vacuolar Fe exporters, AtNRAMP3 and AtNRAMP4, and the chloroplast Fe importer, AtPIC1 . Moreover, the pad2‐1 mutant accumulated higher Fe levels in vacuoles but lower Fe levels in chloroplasts compared to wild type (Columbia ecotype [Col‐0]) under Fe limited conditions. Exogenous GSH treatment enhanced chloroplast Fe contents in Col‐0 but failed to do so in the nramp3nramp4 double mutants demonstrating that GSH plays a role in modulating subcellular Fe homoeostasis. Pharmacological experiments, mutant analysis, and promoter assays revealed that this regulation involves the transcriptional activation of Fe transporter genes by a GSH– S ‐nitrosoglutathione (GSNO) module. The Fe responsive bHLH transcription factors (TFs), At bHLH29, At bHLH38, and At bHLH101 were found to interact with the promoters of these genes, which were, in turn, activated via S ‐nitrosylation (SNO). Taken together, the present study highlights the role of the GSH–GSNO module in regulating subcellular Fe homoeostasis by transcriptional activation of the Fe transporters AtNRAMP3, AtNRAMP4, and AtPIC1 via SNO of bHLH TFs during Fe deficiency. Summary Statement: Glutathione regulates subcellular iron homoeostasis under iron deficiency via S ‐nitrosoglutathione‐dependent transcriptional activation of AtNRAMP3, AtNRAMP4, and AtPIC1 genes by S ‐nitrosylation of the iron‐responsive bHLH transcription factors, At bHLH29, At bHLH38, and At bHLH101.