Absence of Complex I Is Associated with Diminished Respiratory Chain Function in European Mistletoe

Andrew E Maclean, Alexander P Hertle, Joanna Ligas, Ralph Bock, Janneke Balk, Etienne H Meyer

Research output: Contribution to journalArticle

20 Citations (Scopus)
10 Downloads (Pure)

Abstract

Parasitism is a life history strategy found across all domains of life whereby nutrition is obtained from a host. It is often associated with reductive evolution of the genome, including loss of genes from the organellar genomes [1, 2]. In some unicellular parasites, the mitochondrial genome (mitogenome) has been lost entirely, with far-reaching consequences for the physiology of the organism [3, 4]. Recently, mitogenome sequences of several species of the hemiparasitic plant mistletoe (Viscum sp.) have been reported [5, 6], revealing a striking loss of genes not seen in any other multicellular eukaryotes. In particular, the nad genes encoding subunits of respiratory complex I are all absent and other protein-coding genes are also lost or highly diverged in sequence, raising the question what remains of the respiratory complexes and mitochondrial functions. Here we show that oxidative phosphorylation (OXPHOS) in European mistletoe, Viscum album, is highly diminished. Complex I activity and protein subunits of complex I could not be detected. The levels of complex IV and ATP synthase were at least 5-fold lower than in the non-parasitic model plant Arabidopsis thaliana, whereas alternative dehydrogenases and oxidases were higher in abundance. Carbon flux analysis indicates that cytosolic reactions including glycolysis are greater contributors to ATP synthesis than the mitochondrial tricarboxylic acid (TCA) cycle. Our results describe the extreme adjustments in mitochondrial functions of the first reported multicellular eukaryote without complex I.
Original languageEnglish
Pages (from-to)1614-1619.e3
JournalCurrent Biology
Volume28
Issue number10
Early online date3 May 2018
DOIs
Publication statusPublished - 21 May 2018

Keywords

  • plant mitochondria
  • Viscum album
  • hemiparasite
  • NADH:ubiquinone oxidoreductase
  • complex I
  • metabolic flux

Cite this