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bioRxiv · 10.1101/2023.08.30.555573

Altered iron-sulfur cluster transfer in Arabidopsis mitochondria reveals lipoyl synthase as a Janus-faced enzyme that generates toxic sulfide

Pedroletti, L.·Moseler, A.·Timm, S.·Poschet, G.·Homagk, M.·The, J. X.·Wagner, S.·Wirtz, M.·Hell, R.·Meyer, A. J.
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Abstract

Iron-sulfur (Fe-S) cluster are vital cofactors in all domains of life. Mitochondrial Fe-S cluster assembly occurs in two major steps to first build [2Fe-2S] clusters and subsequently assemble these into [4Fe-4S] clusters. The two assembly machineries are interconnected by glutaredoxin S15 (GRXS15) that transfers [2Fe-2S] clusters to the second machinery. Diminished cluster transfer activity of GRXS15 in Arabidopsis mitochondria causes specific defects associated with lipoyl synthase (LIP1) activity. Conversely, overexpression of LIP1 in wild-type plants causes the release of toxic amounts of sulfide that can be detoxified by increasing the capacity for sulfide fixation through overexpression of O-acetylserine-(thiol)-lyase. The release of sulfide by lipoyl synthase causes a disturbance of mitochondrial sulfide homeostasis resulting in distinct and readily observable macroscopic phenotypes. These phenotypes enable a direct readout of consequences resulting from defects in Fe-S cluster assembly or targeted modulation of Fe-S cluster flux in mitochondria.

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Pedroletti, L., Moseler, A., Timm, S., Poschet, G., Homagk, M., The, J. X., Wagner, S., Wirtz, M., Hell, R., Meyer, A. J.. 2023-09-01. Altered iron-sulfur cluster transfer in Arabidopsis mitochondria reveals lipoyl synthase as a Janus-faced enzyme that generates toxic sulfide. https://doi.org/10.1101/2023.08.30.555573

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