由加拿大蒙特利爾大學(xué)科學(xué)家Normand Brisson帶領(lǐng)的一組研究人員鑒定出一類能使基因組避免發(fā)生有害突變的蛋白,。這類蛋白的結(jié)構(gòu)與陀螺十分相似,，Brisson證實它們在防止基因發(fā)生較大重排以致產(chǎn)生多基因拷貝方面起著重要作用。這些蛋白參與一系列的生物現(xiàn)象,，包括病原體防御反應(yīng),。
科研人員研究了該類蛋白在維持?jǐn)M南芥質(zhì)體基因組穩(wěn)定性方面的作用。研究成果發(fā)表于PNAS,。他們發(fā)現(xiàn),，這類螺旋狀的蛋白能與單鏈DNA分子結(jié)合，起到阻止結(jié)合的作用,，從而保證了質(zhì)體基因組的完整性,。將這類蛋白的編碼基因沉默，會使植物葉片出現(xiàn)青白斑,，這是葉綠體失效的癥狀,。
研究人員發(fā)現(xiàn)，這類蛋白不僅能阻止基因組發(fā)生不利轉(zhuǎn)變,，而且還允許發(fā)生一些有利突變,。Brisson說：“這些突變性狀如植物高營養(yǎng)價值,、抗病性及抗氣候變化性等在現(xiàn)代農(nóng)業(yè)中起重要作用。我們的結(jié)果為與之相似的人類基因修復(fù)機(jī)理的研究提供了一種方法,，基因修復(fù)或許對人類進(jìn)化,、脅迫反應(yīng)以及預(yù)防破壞性疾病等具有重要作用。”（生物谷bioon.com）
生物谷推薦原文出處：
PNAS August 25, 2009 vol. 106 no. 34 14693-14698
Whirly proteins maintain plastid genome stability in Arabidopsis
Alexandre Maréchal,1, Jean-Sébastien Parent,1, Félix Véronneau-Lafortune, Alexandre Joyeux, B. Franz Lang and Normand Brisson,2
Department of Biochemistry, Université de Montréal, P.O. Box 6128, Station Centre-ville, Montréal, QC, Canada H3C 3J7
Maintenance of genome stability is essential for the accurate propagation of genetic information and cell growth and survival. Organisms have therefore developed efficient strategies to prevent DNA lesions and rearrangements. Much of the information concerning these strategies has been obtained through the study of bacterial and nuclear genomes. Comparatively, little is known about how organelle genomes maintain a stable structure. Here, we report that the plastid-localized Whirly ssDNA-binding proteins are required for plastid genome stability in Arabidopsis. We show that a double KO of the genes AtWhy1 and AtWhy3 leads to the appearance of plants with variegated green/white/yellow leaves, symptomatic of nonfunctional chloroplasts. This variegation is maternally inherited, indicating defects in the plastid genome. Indeed, in all variegated lines examined, reorganized regions of plastid DNA are amplified as circular and/or head-tail concatemers. All amplified regions are delimited by short direct repeats of 10–18 bp, strongly suggesting that these regions result from illegitimate recombination between repeated sequences. This type of recombination occurs frequently in plants lacking both Whirlies, to a lesser extent in single KO plants and rarely in WT individuals. Maize mutants for the ZmWhy1 Whirly protein also show an increase in the frequency of illegitimate recombination. We propose a model where Whirlies contribute to plastid genome stability by protecting against illegitimate repeat-mediated recombination.
