Two major processes generate cellular energy in eukaryotic organisms: fermentation, which occurs anaerobically, and respiration, which requires oxygen and function in mitochondria production about 80% of the energy needed by most eukaryotic organisms. Therefore mitochondrion is called as the power house of eukaryotes. Many mutants of relative genes function in this organelle would generate important functional deficiency.

Recently, a Max-Planck Junior Scientist Group headed by Prof. Wen Wang from the CAS Kunming Institute of Zoology (KIZ) collaboration with Prof. Zhenglong Gu from Cornell University found that mitochondrial genes perform functional relaxation in a yeast lineage which underwent the whole genome duplication (post-WGD yeast species). With the introduction of aerobic fermentation in post-WGD yeast species, the role of mitochondria in generating energy for cellular growth appeared to have become attenuated. Indeed, most post-WGD yeast species can live even without a functional mitochondrial genome. In the study researchers investigated the impact of this metabolic strategy change on mitochondrial evolution. Protein evolution rate and codon usage patterns indicate that a relaxation of function may have occurred for genes that act in the mitochondria for post-WGD species. By examining the codon usage bias and evolution pattern for a specific regulatory motif, they concluded that the efficient aerobic fermentation system in this lineage might have emerged between the divergence of K. polysporus and S. castellii from their common ancestor after WGD.

The result “Relaxation of yeast mitochondrial functions after whole-genome duplication” has been published online at July 30 in Genome Research (http://genome.cshlp.org/cgi/reprint/gr.074674.107v1).