A Mitochondrial LYR Protein Is Required for Complex I Assembly

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


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / metabolism*
  • DNA, Bacterial / genetics
  • Electron Transport Complex I / metabolism*
  • Gene Deletion
  • Gene Expression Regulation, Plant
  • Holoenzymes / metabolism
  • Iron-Sulfur Proteins / metabolism
  • Mitochondria / metabolism*
  • Mitochondrial Proteins / chemistry
  • Mitochondrial Proteins / metabolism*
  • Models, Biological
  • Organelle Biogenesis
  • Phylogeny
  • Protein Binding
  • Protein Domains
  • Protein Subunits / metabolism
  • Saccharomyces cerevisiae / metabolism
  • Up-Regulation / genetics


  • AT1G76060 protein, Arabidopsis
  • Arabidopsis Proteins
  • DNA, Bacterial
  • Holoenzymes
  • Iron-Sulfur Proteins
  • Mitochondrial Proteins
  • Protein Subunits
  • T-DNA
  • Electron Transport Complex I