Application of the yeast Yarrowia lipolytica as a model to analyse human pathogenic mutations in mitochondrial complex I (NADH:ubiquinone oxidoreductase).
While diagnosis and genetic analysis of mitochondrial disorders has made remarkable progress, we still do not understand how given molecular defects are correlated to specific patterns of symptoms and their severity. Towards resolving this dilemma for the largest and therefore most affected respiratory chain enzyme, we have established the yeast Yarrowia lipolytica as a eucaryotic model system to analyse respiratory chain complex I. For in vivo analysis, eYFP protein was attached to the 30-kDa subunit to visualize complex I and mitochondria. Deletions strains for nuclear coded subunits allow the reconstruction of patient alleles by site-directed mutagenesis and plasmid complementation. In most of the pathogenic mutations analysed so far, decreased catalytic activities, elevated K(M) values, and/or elevated I(50) values for quinone-analogous inhibitors were observed, providing plausible clues on the pathogenic process at the molecular level. Leigh mutations in the 49-kDa and PSST homologous subunits are found in regions that are at the boundaries of the ubiquinone-reducing catalytic core. This supports the proposed structural model and at the same time identifies novel domains critical for catalysis. Thus, Y. lipolytica is a useful lower eucaryotic model that will help to understand how pathogenic mutations in complex I interfere with enzyme function.
Kerscher
Stefan
S
Johann Wolfgang Goethe, Universität Frankfurt, Fachbereich Medizin, Institut für Biochemie I, ZBC, Molekulaire Bioenergetik, Theodor-Stern-Kai 7, Haus 25B, Frankfurt am Main, D-60590, Germany.
Grgic
Ljuban
L
Garofano
Aurelio
A
Brandt
Ulrich
U
D020134:Catalytic Domain; D042967:Electron Transport Complex I / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D028361:Mitochondrial Diseases / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D021122:Protein Subunits; D025062:Yarrowia / Q000235:genetics* / Q000378:metabolism
D021122:Protein Subunits; D042967:Electron Transport Complex I