Disproportionate deficiency of iron-sulfur clusters and subunits of complex I in mitochondrial encephalomyopathy

Pediatric Research
T IchikiT Ozawa

Abstract

To investigate the molecular abnormality in the mitochondria from various tissues of an autopsied patient exhibiting mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes, we have examined the enzymatic activity, iron-sulfur cluster, and subunit composition of the NADH-ubiquinone oxidoreductase (complex I). Rotenone-sensitive NADH-cytochrome c reductase activity was found to be decreased in all the tissues examined. A detailed study of the liver mitochondria has shown that NADH-ubiquinone oxidoreductase activity was greatly diminished. Analysis of the electron paramagnetic resonance spectra of the liver submitochondrial particles revealed a disproportionate deficiency of iron-sulfur clusters in the complex I segment of the respiratory chain. Signals from the clusters N-2 and N-3 diminished more drastically than those from clusters N-1b and N-4. Immunoblotting analysis showed that the 75-kD, 51-kD, and several other subunits were markedly diminished among multiple subunit polypeptides of complex I. These findings suggest that the underlying bases for mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes are defects, at least, in the complex I subunits containing a flavin an...Continue Reading

Citations

Feb 1, 1994·European Journal of Pediatrics·D A ApplegarthL A Clarke
Jan 1, 1990·Journal of the Neurological Sciences·Y KogaS DiMauro
May 8, 1991·European Journal of Biochemistry·H WeissD Preis
Jan 1, 1992·American Journal of Respiratory Cell and Molecular Biology·K ToriiT Ozawa
Mar 1, 1996·The Tohoku Journal of Experimental Medicine·O UemuraN Sugiyama
Mar 3, 2004·Biochimica Et Biophysica Acta·K B ChoksiJ Papaconstantinou
Jul 31, 1990·Biochemical and Biophysical Research Communications·T OzawaB Mayumi
Jan 31, 1991·Biochemical and Biophysical Research Communications·M TanakaT Ozawa

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