title: Rpm2p, a protein subunit of mitochondrial RNase P, physically and genetically interacts with cytoplasmic processing bodies.
abstract: The RPM2 gene of Saccharomyces cerevisiae codes for a protein subunit of mitochondrial RNase P and has another unknown essential function. We previously demonstrated that Rpm2p localizes to the nucleus and acts as a transcriptional activator. Rpm2p influences the level of mRNAs that encode components of the mitochondrial import apparatus and essential mitochondrial chaperones. Evidence is presented here that Rpm2p interacts with Dcp2p, a subunit of mRNA decapping enzyme in the two-hybrid assay, and is enriched in cytoplasmic P bodies, the sites of mRNA degradation and storage in yeast and mammalian cells. When overexpressed, GFP-Rpm2p does not impact the number and size of P bodies; however, it prevents their disappearance when translation elongation is inhibited by cycloheximide. Proteasome mutants, ump1-2 and pre4-2, that bypass essential Rpm2p function, also stabilize P bodies. The stabilization of P bodies by Rpm2p may occur through reduced protein degradation since GFP-Rpm2p expressing cells have lower levels of ubiquitin. Genetic analysis revealed that overexpression of Dhh1p (a DEAD box helicase localized to P bodies) suppresses temperature-sensitive growth of the rpm2-100 mutant. Overexpression of Pab1p (a poly (A)-binding protein) also suppresses rpm2-100, suggesting that Rpm2p functions in at least two aspects of mRNA metabolism. The results presented here, and the transcriptional activation function demonstrated earlier, implicate Rpm2p as a coordinator of transcription and mRNA storage/decay in P bodies.
authors.affiliation: Department of Biochemistry and Molecular Biology and Center for Genetics and Molecular Medicine, School of Medicine, University of Louisville, Louisville, KY, USA. v0stri01@louisville.edu
authors.forename: Vilius
authors.initials: V
authors.lastname: Stribinskis
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Ramos
mesh_terms: D022083:Cytoplasmic Structures / Q000737:chemistry / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D004722:Endoribonucleases; D015966:Gene Expression Regulation, Fungal; D008928:Mitochondria / Q000201:enzymology; D018832:Molecular Chaperones / Q000235:genetics; D010441:Peptide Chain Elongation, Translational; D039102:Poly(A)-Binding Proteins / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D043262:Ribonuclease P / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D013696:Temperature; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D018832:Molecular Chaperones; D039102:Poly(A)-Binding Proteins; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; C450100:pab1 protein, S cerevisiae; C413862:proteassemblin; C400572:DCP2 protein, S cerevisiae; D004722:Endoribonucleases; C519164:RPM2 protein, S cerevisiae; D043262:Ribonuclease P; C445083:DHH1 protein, S cerevisiae; D053487:DEAD-box RNA Helicases