Identification and Characterization of a Common Set of Complex I Assembly Intermediates in Mitochondria from Patients with Complex I Deficiency

Hana Antonicka, Isla Ogilvie, Tanja Taivassalo, Roberto P. Anitori, Ronald G. Haller, John Vissing, Nancy G. Kennaway, Eric A. Shoubridge

Research output: Contribution to journalArticlepeer-review

160 Scopus citations


Deficiencies in the activity of complex I (NADH: ubiquinone oxidoreductase) are an important cause of human mitochondrial disease. Complex I is composed of at least 46 structural subunits that are encoded in both nuclear and mitochondrial DNA. Enzyme deficiency can result from either impaired catalytic efficiency or an inability to assemble the holoenzyme complex; however, the assembly process remains poorly understood. We have used two-dimensional Blue-Native/SDS gel electrophoresis and a panel of 11 antibodies directed against structural subunits of the enzyme to investigate complex I assembly in the muscle mitochondria from four patients with complex I deficiency caused by either mitochondrial or nuclear gene defects. Immunoblot analyses of second dimension denaturing gels identified seven distinct complex I subcomplexes in the patients studied, five of which could also be detected in non-denaturing gels in the first dimension. Although the abundance of these intermediates varied among the different patients, a common constellation of subcomplexes was observed in all cases. A similar profile of subcomplexes was present in a human/mouse hybrid fibroblast cell line with a severe complex I deficiency due to an almost complete lack of assembly of the holoenzyme complex. The finding that diverse causes of complex I deficiency produce a similar pattern of complex I subcomplexes suggests that these are intermediates in the assembly of the holoenzyme complex. We propose a possible assembly pathway for the complex, which differs significantly from that proposed for Neurospora, the current model for complex I assembly.

Original languageEnglish (US)
Pages (from-to)43081-43088
Number of pages8
JournalJournal of Biological Chemistry
Issue number44
StatePublished - Oct 31 2003

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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