Parallel inactivation of multiple GAL pathway genes and ecological diversification in yeasts
Parallel inactivation of multiple GAL pathway genes and ecological diversification in yeasts
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DOI：
10.1073/pnas.0404319101
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发表时间：
2004-09-28
影响因子：
11.1
通讯作者：
Carroll, SB
中科院分区：
文献类型：
--
作者：
Hittinger, CT;Rokas, A;Carroll, SB
理解基因组内容和生态位之间的进化关系是生物学的基本挑战之一。酵母物种的独特生理学为了解基因组如何与生态位协同进化提供了一个窗口。虽然充分研究的酵母半乳糖利用途径的酶存在于生命的所有领域，但我们发现GAL途径的多个基因不存在于不能利用半乳糖的四种酵母物种中。而三个物种缺乏任何痕迹的途径，除了一个单一的基因，酵母kudriavzevii，酿酒酵母的近亲，保留了所有七个专用GAL基因的残余作为同线假基因，提供了一个罕见的一瞥整个途径的退化过程。对基因失活时间的估计表明，通路退化在谱系早期就开始了，并且进行得很快。S. kudriavzevii表现出与生态位转变相关的其他几种不同的生理特性。这些结果表明，快速和不可逆的基因失活和途径退化与适应新的生态位在自然种群。失活的基因通常可以作为特定功能的标记，这些功能被最近的适应性转变所取代。
Understanding the evolutionary relationship between genome content and ecological niche is one of the fundamental challenges of biology. The distinct physiologies of yeast species provide a window into how genomes evolve in concert with niche. Although the enzymes of the well studied yeast galactose utilization pathway are present in all domains of life, we have found that multiple genes of the GAL pathway are absent from four yeast species that cannot use galactose. Whereas three species lack any trace of the pathway except a single gene, Saccharomyces kudriavzevii, a close relative of Saccharomyces cerevisiae, retains remnants of all seven dedicated GAL genes as syntenic pseudogenes, providing a rare glimpse of an entire pathway in the process of degeneration. An estimate of the timing of gene inactivation suggests that pathway degeneration began early in the lineage and proceeded rapidly. S. kudriavzevii exhibits several other divergent physiological properties that are associated with a shift in ecological niche. These results suggest that rapid and irreversible gene inactivation and pathway degeneration are associated with adaptation to new ecological niches in natural populations. Inactivated genes may generally serve as markers of specific functions made dispensable by recent adaptive shifts.