6月24日,，Nature雜志在線報(bào)道了通過(guò)遺傳進(jìn)化，從頭產(chǎn)生新基因的最新研究進(jìn)展,。
新型蛋白質(zhì)編碼基因可以通過(guò)重新組織預(yù)先存在的基因或以從頭產(chǎn)生的方式出現(xiàn),。通過(guò)重新組織預(yù)先存在的基因，特別是通過(guò)基因重復(fù)來(lái)重新組織產(chǎn)生新的基因的過(guò)程,，已經(jīng)被廣泛研究過(guò),。相比之下,，人類對(duì)從頭產(chǎn)生基因的進(jìn)化過(guò)程仍然知之甚少，主要是因?yàn)檠芯空咭酝J(rèn)為所謂的"非基因"序列的翻譯將產(chǎn)生微不足道的多肽,，而不是具有特定的生物功能的蛋白質(zhì),。
本研究建立了一種基因演化模型，根據(jù)這一模型,，非基因序列廣泛的翻譯活動(dòng)可產(chǎn)生過(guò)渡性原基因,，而功能基因又可從過(guò)渡性原基因進(jìn)化而來(lái)。研究者在釀酒酵母菌基因組范圍內(nèi)檢測(cè)這個(gè)模型,。在非基因序列中,，研究者發(fā)現(xiàn)數(shù)百個(gè)短的物種特異性的開(kāi)放閱讀框（ORF）的翻譯活動(dòng)。根據(jù)它們對(duì)選擇壓力的差異性調(diào)節(jié)反應(yīng)和通過(guò)自然選擇保留的印記來(lái)看,，這些翻譯事件似乎提供了某種適應(yīng)性潛力,。與此模型相對(duì)應(yīng)，研究者發(fā)現(xiàn)釀酒酵母的ORF正好處于,，從非基因序列進(jìn)化到新的基因這一連續(xù)的過(guò)程中承上啟下的位置上,。
研究者在釀酒酵母的ORF中，確定了約1900個(gè)候選原基因,。從這樣一個(gè)寶庫(kù)中從頭產(chǎn)生新基因可能會(huì)比從零星的基因重復(fù)事件中產(chǎn)生更為普遍,。該研究表明,，進(jìn)化作用可利用看似可有可無(wú)的序列來(lái)產(chǎn)生適應(yīng)性的功能創(chuàng)新,。（生物谷bioon.com）
doi:10.1016/j.cell.2011.10.017
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Proto-genes and de novo gene birth
Anne-Ruxandra Carvunis,1, 2, 3 Thomas Rolland,1, 2 Ilan Wapinski,4 Michael A. Calderwood,1, 2 Muhammed A. Yildirim,5 Nicolas Simonis,1, 2, 11 Benoit Charloteaux,1, 2, 6 César A. Hidalgo,7 Justin Barbette,1, 2 Balaji Santhanam,1, 2 Gloria A. Brar,8 Jonathan S. Weissman,8 Aviv Regev,9, 10 Nicolas Thierry-Mieg,3 Michael E. Cusick1, 2 & Marc Vidal1, 2
Novel protein-coding genes can arise either through re-organization of pre-existing genes or de novo1, 2. Processes involving re-organization of pre-existing genes, notably after gene duplication, have been extensively described1, 2. In contrast, de novo gene birth remains poorly understood, mainly because translation of sequences devoid of genes, or ‘non-genic’ sequences, is expected to produce insignificant polypeptides rather than proteins with specific biological functions1, 3, 4, 5, 6. Here we formalize an evolutionary model according to which functional genes evolve de novo through transitory proto-genes4 generated by widespread translational activity in non-genic sequences. Testing this model at the genome scale in Saccharomyces cerevisiae, we detect translation of hundreds of short species-specific open reading frames (ORFs) located in non-genic sequences. These translation events seem to provide adaptive potential7, as suggested by their differential regulation upon stress and by signatures of retention by natural selection. In line with our model, we establish that S. cerevisiae ORFs can be placed within an evolutionary continuum ranging from non-genic sequences to genes. We identify ~1,900 candidate proto-genes among S. cerevisiae ORFs and find that de novo gene birth from such a reservoir may be more prevalent than sporadic gene duplication. Our work illustrates that evolution exploits seemingly dispensable sequences to generate adaptive functional innovation.
