Mitochondrial ribosome content as a proxy for respiration

Abstract Quantifying cellular activities remains a major challenge across fields ranging from microbial ecology to biotechnology and biomedical sciences. Building on the well-established linear relationship between growth rate and ribosome content — the so-called microbial growth law — this study proposes using organelle ribosome content to infer metabolic activity. In exponentially growing yeast, including under overflow conditions, a strong linear correlation was observed between mitochondrial ribosome content and oxygen uptake rate, demonstrating the robustness and potential of this approach. In addition, cytoplasmic and mitochondrial ribosome fractions exhibited a linear relationship, while overflow conditions appeared as outliers, providing a means to identify such metabolic states. Altogether, these findings highlight the promise of organelle ribosome quantification as a novel proxy for deciphering cellular metabolism. Competing Interest Statement The authors have declared no competing interest.