Abstract
The regulation of cellular growth is crucial in the control of cell proliferation. While most of the metabolic energy necessary to sustain growth is produced in mitochondria, the regulation of mitochondrial activity and its implications for growth have remained unexplored. Here, a gene named bonsa?s described, which is essential for normal growth in Drosophila. The Bonsa?rotein bears strong homology to prokaryotic ribosomal protein S15 and localizes to mitochondria, suggesting a role in mitochondrial protein translation. Accordingly, bonsa?utants have defective mitochondrial activity, but surprisingly, only the gut appears affected. Consistent with these observations, bonsa?s predominantly expressed in the gut. These results show that bonsa?lays a preponderant role in gut mitochondria. Although gut mitochondrial respiration is altered in bonsa?utants, the digestive process appears normal, suggesting that a gut function other than digestion is impaired in the mutants. Cytochrome c oxidase, a respiratory chain enzyme partly encoded by the mitochondrial genome, is found to be active in bonsa?utants. This suggests that mitochondrial translation is not abolished in the mutants. Altogether, these observations suggest that mitochondrial activity is regulated at the tissue-specific level and that this regulation has profound implications for growth and development.