Protein lipoylation in mitochondria requires Fe–S cluster assembly factors NFU4 and NFU5

Przybyla-Toscano, J., MacLean, A. E., Franceschetti, M., Liebsch, D., Vignols, F., Keech, O., Rouhier, N. and Balk, J. (2022) Protein lipoylation in mitochondria requires Fe–S cluster assembly factors NFU4 and NFU5. Plant Physiology, 188(2), pp. 997-1013. (doi: 10.1093/plphys/kiab501) (PMID:34718778) (PMCID:PMC8825329)

Abstract

Plants have evolutionarily conserved NifU (NFU)-domain proteins that are targeted to plastids or mitochondria. “Plastid-type” NFU1, NFU2, and NFU3 in Arabidopsis (Arabidopsis thaliana) play a role in iron–sulfur (Fe–S) cluster assembly in this organelle, whereas the type-II NFU4 and NFU5 proteins have not been subjected to mutant studies in any plant species to determine their biological role. Here, we confirmed that NFU4 and NFU5 are targeted to the mitochondria. The proteins were constitutively produced in all parts of the plant, suggesting a housekeeping function. Double nfu4 nfu5 knockout mutants were embryonic lethal, and depletion of NFU4 and NFU5 proteins led to growth arrest of young seedlings. Biochemical analyses revealed that NFU4 and NFU5 are required for lipoylation of the H proteins of the glycine decarboxylase complex and the E2 subunits of other mitochondrial dehydrogenases, with little impact on Fe–S cluster-containing respiratory complexes or aconitase. Consequently, the Gly-to-Ser ratio was increased in mutant seedlings and early growth improved with elevated CO2 treatment. In addition, pyruvate, 2-oxoglutarate, and branched-chain amino acids accumulated in nfu4 nfu5 mutants, further supporting defects in the other three mitochondrial lipoate-dependent enzyme complexes. NFU4 and NFU5 interacted with mitochondrial lipoyl synthase (LIP1) in yeast 2-hybrid and bimolecular fluorescence complementation assays. These data indicate that NFU4 and NFU5 have a more specific function than previously thought, most likely providing Fe–S clusters to lipoyl synthase.

• Item Type: Articles
• Additional Information: Funding: This work was supported by a studentship from the John Innes Foundation to A.E.M.; the Biotechnology and Biological Sciences Research Council, grant awards BB/P012523/1 and BB/P012574/1 to M.F. and J.B; funding from the T4F Trees for the Future and the Kempe Foundations (GO¨ F) to O.K. and D.L.; the French National Research Agency, grant awards ANR-13-BSV6-0002-01, ANR-11-LABX-0002-01 (Lab of Excellence ARBRE) and ANR-15-IDEX-04-LUE (Lorraine Universite´ d’Excellence) to N.R. and J.P.-T.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacLean, Dr Andrew
• Authors: Przybyla-Toscano, J., MacLean, A. E., Franceschetti, M., Liebsch, D., Vignols, F., Keech, O., Rouhier, N., and Balk, J.
• College/School: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Journal Name: Plant Physiology
• Publisher: Oxford University Press
• ISSN: 0032-0889
• ISSN (Online): 1532-2548
• Published Online: 28 October 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Plant Physiology 188(2): 997-1013
• Publisher Policy: Reproduced under a Creative Commons licence