Application of the obligate aerobic yeast Yarrowia lipolytica as a eucaryotic model to analyse Leigh syndrome mutations in the complex I core subunits PSST and TYKY

We have used the obligate aerobic yeast Yarrowia lipolytica to reconstruct and analyse three missense mutations in the nuclear coded subunits homologo us to bovine TYKY and PSST of mitochondrial complex I (proton translocating NADH:ubiquinone oxidoreductase) that have been shown to cause Leigh syndro me (MIM 25600), a severe progressive neurodegenerative disorder. While homo zygosity for a V122M substitution in NDUFS7 (PSST) has been found in two si blings with neuropathologically proven Leigh syndrome (R. Triepels et al., Ann. Neurol. 45 (1999) 787), heterozygosity for a P79L and a R102H substitu tion in NDUFS8 (TYKY) has been found in another patient (J. Loeffen et al., Am. J. Hum. Genet. 63 (1998) 1598). Mitochondrial membranes from Y. lipoly tica strains carrying any of the three point mutations exhibited similar co mplex I defects, with V-max being reduced by about 50%. This suggests that complex I mutations that clinically present as Leigh syndrome may share com mon characteristics. In addition changes in the k(m) for n-decyl- ubiquinon e and I-50 for hydrophobic complex I inhibitors were observed, which provid es further evidence that not only the hydrophobic. mitochondrially coded su bunits, but also some of the nuclear coded subunits of complex I are involv ed in its reaction with ubiquinone. (C) 2000 Elsevier Science B.V. All righ ts reserved.