A Mitochondrial LYR Protein Is Required for Complex I Assembly

Aneta Ivanova, Mabel Gill-Hille, Shaobai Huang, Rui M. Branca, Beata Kmiec, Pedro F. Teixeira, Janne Lehtiö, James Whelan, Monika W. Murcha

Research output: Contribution to journalArticlepeer-review

15 Citations (Web of Science)


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.

Original languageEnglish
Pages (from-to)1632-1650
Number of pages19
JournalPlant Physiology
Issue number4
Publication statusPublished - 1 Dec 2019


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