title: Insights into the pathogenic character of a common NUBPL branch-site mutation associated with mitochondrial disease and complex I deficiency using a yeast model.
abstract: Complex I deficiencies are the most common causes of mitochondrial disorders. They can result from mutations not only in the structural subunits but also in a growing number of known assembly factors. A branch-site mutation in the human gene encoding assembly factor NUBPL has recently been associated with mitochondrial encephalopathy and complex I deficiency in seven independent cases. Moreover, the mutation is present in 1.2% of European haplotypes. To investigate its pathogenicity, we have reconstructed the altered C-terminus that results from the branch-site mutation and frameshift in the homologous Ind1 protein in the respiratory yeast Yarrowia lipolytica. We demonstrate that the altered sequence did not affect IND1 mRNA stability, yet it led to a decrease in Ind1 protein level. The instability of mutant Ind1 resulted in a strong decrease in complex I activity and caused slow growth, resembling the phenotype of the deletion strain of IND1. The presented data confirms the deleterious impact of the altered C-terminus resulting from the branch-site mutation. Furthermore, our approach demonstrates the great potential of Y. lipolytica as a model to investigate complex I deficiencies, especially in cases with genetic complexity.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.
authors.forename: Mateusz M
authors.initials: MM
authors.lastname: Wydro
authors.forename: Janneke
authors.initials: J
authors.lastname: Balk
mesh_terms: D000595:Amino Acid Sequence; D042967:Electron Transport Complex I / Q000172:deficiency* / Q000378:metabolism; D016368:Frameshift Mutation / Q000235:genetics*; D005656:Fungal Proteins / Q000737:chemistry; D005816:Genetic Complementation Test; D020022:Genetic Predisposition to Disease; D006801:Humans; D028361:Mitochondrial Diseases / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics*; D008954:Models, Biological; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D055550:Protein Stability; D020871:RNA Stability / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D025062:Yarrowia / Q000235:genetics*
chemical_list: D005656:Fungal Proteins; D024101:Mitochondrial Proteins; C572056:NUBPL protein, human; D012333:RNA, Messenger; D042967:Electron Transport Complex I