dictyNews Electronic Edition Volume 39, number 9 March 29, 2013 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of dictyNews, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. Follow dictyBase on twitter: http://twitter.com/dictybase ========= Abstracts ========= Ndufaf5 deficiency in the Dictyostelium model: new roles in autophagy and development Sergio Carilla-Latorre, Sarah J. Annesley, Sandra Mu–oz-Braceras, Paul R. Fisher, and Ricardo Escalante Molecular Biology of the Cell, in press Ndufaf5 (also known as C20orf7) is a mitochondrial complex I (CI) assembly factor whose mutations lead to human mitochondrial disease. Little is known about the function of the protein and the cytopathological consequences of the mutations. Disruption of Dictyostelium Ndufaf5 leads to CI deficiency and defects in growth and development. The predicted sequence of Ndufaf5 contains a putative methyltransferase domain. Site-directed mutagenesis indicates that the methyltransferase motif is essential for its function. Pathological mutations were recreated in the Dictyostelium protein and expressed in the mutant background. These proteins were unable to complement the phenotypes, which further validates Dictyostelium as a model of the disease. Chronic activation of AMP-activated protein kinase (AMPK) has been proposed to play a role in Dictyostelium and human cytopathology in mitochondrial diseases. However, inhibition of the expression of AMPK gene in the Ndufaf5 null mutant does not rescue the phenotypes associated with the lack of Ndufaf5 suggesting that novel AMPK-independent pathways are responsible of Ndufaf5 cytopathology. Interestingly, the Ndufaf5 deficient strain shows an increase in autophagy. This phenomenon was also observed in a Dictyostelium mutant lacking MidA (C2orf56/PRO1853/Ndufaf7), another CI assembly factor, suggesting that autophagy activation might be a common feature in mitochondrial CI dysfunction. Submitted by Ricardo Escalante [rescalante@iib.uam.es] ============================================================== [End dictyNews, volume 39, number 9]