Zapisek 2014 Abstract MiP2014
|YER077C encodes a novel PPR protein essential for mitochondrial genome expression in Saccharomyces cerevisiae.|
Mitochondria possess a residual genome which encodes only a few proteins, including some key proteins of oxidative phosphorylation (OXPHOS) complexes. Therefore, the mitochondrial genome maintenance and expression is highly dependent on a variety of proteins encoded by the nuclear genome [1,2]. Pentatricopeptide repeat (PPR) proteins form the largest known RNA-binding protein family and are found in all eukaryotes, where they play an essential role in organellar genome expression . The budding yeast Saccharomyces cerevisiae has traditionally been a leading model for the study of mitochondrial gene expression and the biogenesis of OXPHOS complexes .
We report a new nuclear gene, reading frame ∆yer077C on chromosome V, encoding a mitochondrial PPR protein required for the proper expression of mitochondrial genetic information on the RNA level in S. cerevisiae. Regardless of the presence of introns in mtDNA, the lack of ∆yer077C gene product results in a complete loss of respiratory capacity and increased mtDNA instability leading to conversion to ρ−/ρ0 petites. Northern analysis of mitochondrial RNA in the ∆yer077C strain revealed the abolished levels for the transcripts encoding essential subunits for the mitochondrial cytochrome bc1 and ATPase complexes (i.a. accumulation of pre-RNA and strongly decreased levels of mRNA). Sucrose gradient sedimentation analyzes suggest that yer077cp might bind to a small subunit of mitochondrial ribosome and also to fully assembled mitoribosomes.
In view of our results and the RNA-binding properties of known PPR proteins, we conclude that yer077cp is an important factor for mitochondrial RNA maturation and stability and thus an essential component of the mitochondrial gene expression system. The interaction with mitoribosomes might also reveal yer077cp as a potential mRNA translational activator which has already been annotated for other yeast PPR proteins .
Labels: MiParea: mtDNA;mt-genetics Mammal;model: Saccharomyces cerevisiae Coupling state: OXPHOS Event: A1, Poster Additional: MiP2014
1-Inst Genet Biotechn, Univ Warsaw; 2-Inst Bioch Biophysics, Polish Acad Sc, Warsaw; Poland. - email@example.com
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