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Plant Physiol. 2019 Dec;181(4):1632-1650. doi: 10.1104/pp.19.00822. Epub 2019 Oct 10.

A Mitochondrial LYR Protein Is Required for Complex I Assembly.

Author information

1
School of Chemistry and Biochemistry, The University of Western Australia, Crawley, Perth 6009, Australia.
2
The Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Perth 6009, Australia.
3
Clinical Proteomics Mass Spectrometry, Department of Oncology-Pathology, Science for Life Laboratory and Karolinska Institutet, Stockholm 171 77, Sweden.
4
Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, Stockholm SE-106 91, Sweden.
5
Department of Animal, Plant and Soil Science, School of Life Science, The ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora 3086, Australia.
6
School of Chemistry and Biochemistry, The University of Western Australia, Crawley, Perth 6009, Australia monika.murcha@uwa.edu.au.

Abstract

Complex I biogenesis requires the expression of both nuclear and mitochondrial genes, the import of proteins, cofactor biosynthesis, and the assembly of at least 49 individual subunits. Assembly factors interact with subunits of Complex I but are not part of the final holocomplex. We show that in Arabidopsis (Arabidopsis thaliana), a mitochondrial matrix protein (EMB1793, At1g76060), which we term COMPLEX I ASSEMBLY FACTOR 1 (CIAF1), contains a LYR domain and is required for Complex I assembly. T-DNA insertion mutants of CIAF1 lack Complex I and the Supercomplex I+III. Biochemical characterization shows that the assembly of Complex I is stalled at 650 and 800 kD intermediates in mitochondria isolated from ciaf1 mutant lines.I. Yeast-two-hybrid interaction and complementation assays indicate that CIAF1 specifically interacts with the 23-kD TYKY-1 matrix domain subunit of Complex I and likely plays a role in Fe-S insertion into this subunit. These data show that CIAF1 plays an essential role in assembling the peripheral matrix arm Complex I subunits into the Complex I holoenzyme.

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