While cells can generate ATP through mitochondrial oxidative phosphorylation, they can also use glycolysis as an alternative means of generating ATP. This has to be coordinated with the gene expression of the mitochondrial genome, which in Saccharomyces cerevisiae contains 13 genes ( Borst and Grivell, 1978). To support mitochondrial function, proteins from hundreds of nuclear genes are imported into mitochondria from the cytoplasm ( Morgenstern et al., 2017). Mitochondria are essential cellular organelles that are key sources of ATP generation via oxidative phosphorylation as well as the assembly of iron-sulfur clusters and many other catabolic and anabolic reactions ( Attardi and Schatz, 1988). This points to a mechanism by which cells are able to use translation elongation and the geometric constraints of the cell to fine-tune organelle-specific gene expression through mRNA localization. Furthermore, we find that ribosome stalling impacts mRNA sensitivity to mitochondrial volume fraction and counterintuitively leads to enhanced protein synthesis by increasing mRNA localization to mitochondria. We show that mitochondrial mRNA localization is necessary and sufficient to increase protein production to levels required during respiratory growth. Our data point to this change in mitochondrial volume fraction increasing the localization of certain nuclear-encoded mRNAs to the surface of the mitochondria. As yeast switch to respiratory metabolism, there is an increase in the fraction of the cytoplasm that is mitochondrial. Although nuclear-encoded mRNAs can be localized to the mitochondrial surface, the importance of this localization is unclear. Mitochondria are dynamic organelles that must precisely control their protein composition according to cellular energy demand.

Localizer translation