title: MidA is a putative methyltransferase that is required for mitochondrial complex I function.
abstract: Dictyostelium and human MidA are homologous proteins that belong to a family of proteins of unknown function called DUF185. Using yeast two-hybrid screening and pull-down experiments, we showed that both proteins interact with the mitochondrial complex I subunit NDUFS2. Consistent with this, Dictyostelium cells lacking MidA showed a specific defect in complex I activity, and knockdown of human MidA in HEK293T cells resulted in reduced levels of assembled complex I. These results indicate a role for MidA in complex I assembly or stability. A structural bioinformatics analysis suggested the presence of a methyltransferase domain; this was further supported by site-directed mutagenesis of specific residues from the putative catalytic site. Interestingly, this complex I deficiency in a Dictyostelium midA(-) mutant causes a complex phenotypic outcome, which includes phototaxis and thermotaxis defects. We found that these aspects of the phenotype are mediated by a chronic activation of AMPK, revealing a possible role of AMPK signaling in complex I cytopathology.
authors.affiliation: Instituto de Investigaciones Biomédicas Alberto Sols (CSIC-UAM), Arturo Duperier 4, 28029 Madrid, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Carilla-Latorre
authors.forename: M Esther
authors.initials: ME
authors.lastname: Gallardo
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Annesley
authors.forename: Javier
authors.initials: J
authors.lastname: Calvo-Garrido
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Graña
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Accari
authors.forename: Paige K
authors.initials: PK
authors.lastname: Smith
authors.forename: Alfonso
authors.initials: A
authors.lastname: Valencia
authors.forename: Rafael
authors.initials: R
authors.lastname: Garesse
authors.forename: Paul R
authors.initials: PR
authors.lastname: Fisher
authors.forename: Ricardo
authors.initials: R
authors.lastname: Escalante
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D020134:Catalytic Domain / Q000235:genetics; D002465:Cell Movement / Q000235:genetics; D019295:Computational Biology; D004023:Dictyostelium; D042967:Electron Transport Complex I / Q000378:metabolism; D006801:Humans; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D009245:NADH Dehydrogenase / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: C000598027:NDUFAF7 protein, human; D015800:Protozoan Proteins; D034741:RNA, Small Interfering; D009245:NADH Dehydrogenase; D008780:Methyltransferases; D011494:Protein Kinases; D000091162:AMP-Activated Protein Kinase Kinases; D042967:Electron Transport Complex I; C496411:NDUFS2 protein, human