With the expansion of fruit plants at the end of the Cretaceous period, the ancestor of the Saccharomyces lineage generated a novel trait of aerobic fermentation to survive in an environment with abundant fermentable fruits.
During aerobic fermentation, the yeast can repress the expression of mitochondrial genes, rapidly consume glucose, accumulate ethanol, and out-compete other microbes. Therefore, the formation mechanism of aerobic fermentation is always a hotspot.
Many studies have shown that the whole genome duplication (WGD) event that happened around 100 million years ago played an important role in the origin of aerobic fermentation in Saccharomyces.
Recently, scientists from Tianjin Institute of Industrial Biotechnology of the Chinese Academy of Sciences found that, about 300 million years ago, the other wine and beer yeast Dekkera bruxellensis diverged from the Saccharomyces cerevisiae, long before WGD, also generated the capacity of aerobic fermentation.
By profiling and comparing genome sequences, transcriptomic landscapes and chromatin structures, they revealed the fact that no WGD occurred in Dekkera lineage.
Surprisingly, the two independent evolutionary lineages evolved similar AT-rich elements in promoter regions of mitochondrial genes, which underlay the parallel changes in chromatin structure and led to concerted suppression of mitochondrial functions by glucose and metabolic convergence in these two independent yeast species.
The study confirmed that similar genetic mechanism and metabolic pathway can emerge in independent evolutionary lineages for improving adaptability in the same conditions.
The study entitled "Parallel Evolution of Chromatin Structure Underlying Metabolic Adaptation" has been published in Molecular Biology and Evolution.
This research was supported by two National Natural Science Foundation of China (NSFC) grants and The Hundred Talent Program of the Chinese Academy of Sciences to H.J, and NSF grant MCB-1243588 to Z.G.
Parallel evolution of gene expression between D. bruxellensis and S. cerevisiae. (A) Relative gene expression for genes from catabolic pathways and the TCA cycle. (B) Relative gene expression for mitochondrial genes and growth associated genes in YPD compared to YPEG. (Image by TIB)
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