Since the discovery of somatic mtDNA mutations in tumor cells, multiple studies have focused on establishing a
causal relationship between those changes and alterations in energy metabolism, a hallmark of cancer cells. Yet
the consequences of these mutations on mitochondrial function remain largely unknown. In this study, Saccharomyces cerevisiae has been used as a model to investigate the functional consequences of four cancer-associated missense mutations (8914CNA, 8932CNT, 8953ANG, 9131TNC) found in the mitochondrial MT-ATP6 gene. This
gene encodes the a-subunit of F1FO-ATP synthase, which catalyzes the last steps of ATP production in mitochondria. Although the four studied mutations affected well-conserved residues of the a-subunit, only one of them (8932CNT) had a significant impact on mitochondrial function, due to a less efficient incorporation of the asubunit into ATP synthase. Our findings indicate that these ATP6 genetic variants found in human tumors are neutral mitochondrial genome substitutions with a limited, if any, impact on the energetic function of mitochondria
