Nucleic Acids Research Advance Access originally published online on January 31, 2007
Nucleic Acids Research 2007 35(4):1301-1311; doi:10.1093/nar/gkm023
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Nucleic Acids Research, 2007, Vol. 35, No. 4 1301-1311
© 2007 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Molecular Biology |
Rpm2p, a protein subunit of mitochondrial RNase P, physically and genetically interacts with cytoplasmic processing bodies
Department of Biochemistry and Molecular Biology and Center for Genetics and Molecular Medicine, School of Medicine, University of Louisville, Louisville, KY, USA
*To whom correspondence should be addressed. Tel: +1 502 852 7368; Fax: +1 502 852 3659; Email: v0stri01{at}louisville.edu
Received June 21, 2006. Revised December 21, 2006. Accepted January 3, 2007.
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.