Arabidopsis glutathione reductase 2 is indispensable in plastids, while mitochondrial glutathione is safeguarded by additional reduction and transport systems

Marty, L.; Bausewein, D.; Müller, C.; Bangash, S. A. K.; Moseler, A.; Schwarzländer, M.; Müller-Schüssele, S. J.; Zechmann, B.; Riondet, C.; Balk, J.; Wirtz, M.; Hell, R.; Reichheld, J.-P.; Meyer, A. J.

doi:10.1101/610477

bioRxiv · 10.1101/610477

Arabidopsis glutathione reductase 2 is indispensable in plastids, while mitochondrial glutathione is safeguarded by additional reduction and transport systems

Marty, L.·Bausewein, D.·Müller, C.·Bangash, S. A. K.·Moseler, A.·Schwarzländer, M.·Müller-Schüssele, S. J.·Zechmann, B.·Riondet, C.·Balk, J.·Wirtz, M.·Hell, R.·Reichheld, J.-P.·Meyer, A. J.

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Abstract

O_LIA highly negative glutathione redox potential (EGSH) is maintained in the cytosol, plastids and mitochondria of plant cells to support fundamental processes, including antioxidant defence, redox regulation and iron-sulfur cluster biogenesis. Out of two glutathione reductase (GR) proteins in Arabidopsis, GR2 is predicted to be dual-targeted to plastids and mitochondria, but its differential roles in these organelles remain unclear.\nC_LIO_LIWe dissected the role of GR2 in organelle glutathione redox homeostasis and plant development using a combination of genetic complementation and stacked mutants, biochemical activity studies, immunogold labelling and in vivo biosensing.\nC_LIO_LIOur data demonstrate that GR2 is dual-targeted to plastids and mitochondria, but embryo lethality of gr2 null mutants is caused specifically in plastids. Whereas lack of mitochondrial GR2 leads to a partially oxidised glutathione pool in the matrix, the ABC transporter ATM3 and the mitochondrial thioredoxin system provide functional backup and maintain plant viability.\nC_LIO_LIWe identify GR2 as essential in the plastid stroma, where it counters GSSG accumulation and developmental arrest. By contrast a functional triad of GR2, ATM3 and the thioredoxin system in the mitochondria provides resilience to excessive glutathione oxidation.\nC_LI

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Marty, L., Bausewein, D., Müller, C., Bangash, S. A. K., Moseler, A., Schwarzländer, M., Müller-Schüssele, S. J., Zechmann, B., Riondet, C., Balk, J., Wirtz, M., Hell, R., Reichheld, J.-P., Meyer, A. J.. 2019-04-16. Arabidopsis glutathione reductase 2 is indispensable in plastids, while mitochondrial glutathione is safeguarded by additional reduction and transport systems. https://doi.org/10.1101/610477

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