“The control of protein import into mitochondria is essential for their functions (e.g. ATP synthesis, lipid metabolism, calcium storage, etc.), however, the precise mechanism of protein import – whether it is post-translational, co-translational, or a combination thereof - is still open for debate. Yeast have >600 nuclear genes encoding for mitochondrial proteins and we are studying the process by which mRNAs encoding mitochondrial proteins (mMPs) may reach the mitochondria. By employing a novel endogenous mRNA tagging and visualization procedure developed in our lab, called m-TAG [Haim et al 2007, Haim-Vilmovsky and Gerst 2009, Haim-Vilmovsky and Gerst 2011], we have found that a number of mMPs associate with mitochondria and in a manner that is dependent upon cis-acting elements in the messages and trans-acting RNA-binding proteins [Gadir et al., 2011]. Ongoing work using RaPID, an RNA purification procedure developed in our laboratory to affinity purify aptamer-tagged mRNAs [Slobodin and Gerst, 2010 and 2011], has identified components of the COPI intracellular vesicular trafficking pathway as mediating mMP localization [Zabezhinsky et al., 2016]. Upon inactivation of this pathway, defects in mitochondrial morphology, protein import, and mitochondrial function occur and lead to cell death.
mRNA trafficking to the mitochondria and its role in mitochondrial function
mRNA encoding Oxa1 (green), a mitochondrial inner membrane protein, localizes to the mitochondria (red)