奧地利格雷戈爾·門德爾植物分子生物學(xué)研究所日前宣布,，一個包括該研究所,、中國同濟大學(xué),、美國加利福尼亞大學(xué)等機構(gòu)科學(xué)家在內(nèi)的國際科研小組發(fā)現(xiàn)了一種特殊基因,，沒有它,，植物細(xì)胞內(nèi)其他一些基因就只能保持沉默,。
最新一期英國《自然》雜志網(wǎng)絡(luò)版發(fā)表了這個國際科研小組的論文,。這一科研小組發(fā)現(xiàn)的特殊基因名為RDM1，它可以編碼生成一種小蛋白,，從而參與指導(dǎo)其他基因的表達(dá),。
科學(xué)家指出，基因一般處于被保護(hù)狀態(tài)中,，只有通過所謂的甲基化,，即與甲基接觸，才能表達(dá)并發(fā)揮作用,。如果去除RDM1,，被保護(hù)的基因就無法甲基化，也就無法進(jìn)行表達(dá),。
由于每一個植物細(xì)胞中都存在著完整的遺傳信息,，因此必須讓某些基因保持“沉默”，植物具體的器官才能順利地發(fā)揮各自作用,。否則,，所有基因就會都來表達(dá)，植物器官也將不知道聽從誰的“指令”,。一般在一個植物的上萬個基因里，只有很少的一部分能夠表達(dá),，RNA（核糖核酸）會對需要表達(dá)的基因進(jìn)行標(biāo)記,。RDM1基因的任務(wù)就是讓RNA標(biāo)記過的基因表達(dá)。缺少了RDM1,，植物中許多本該表達(dá)的基因就會保持“沉默”,，植物無法正常生長。(生物谷Bioon.com)
延伸閱讀
Nature：有絲分裂過程中引起基因沉默的原因
The Plant Journal：人工miRNA介導(dǎo)基因沉默
Science：RNAi調(diào)控基因沉默的研究
Nature Cell Biology：美開發(fā)出新型基因沉默技術(shù)
生物谷推薦原文出處：
Nature doi:10.1038/nature09025
An RNA polymerase II- and AGO4-associated protein acts in RNA-directed DNA methylation
Zhihuan Gao1,10, Hai-Liang Liu1,2,10, Lucia Daxinger3,10,11, Olga Pontes4,10, Xinjian He1,5, Weiqiang Qian1, Huixin Lin1, Mingtang Xie1, Zdravko J. Lorkovic6, Shoudong Zhang1,5, Daisuke Miki1, Xiangqiang Zhan1,5, Dominique Pontier7, Thierry Lagrange7, Hailing Jin8, Antonius J. M. Matzke3, Marjori Matzke3, Craig S. Pikaard9 & Jian-Kang Zhu1,5
Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
School of life science and technology, Tongji University, Shanghai 200092, China
Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, 1030 Vienna, Austria
Biology Department, Washington University, St Louis, Missouri 63130, USA
Center for Plant Stress Genomics and Technology, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
Max F. Perutz Laboratory, Medical University of Vienna, 1030 Vienna, Austria
LGDP, CNRS/IRD/Université de Perpignan, UMR 5096, 66860 Perpignan, France
Institute for Integrative Genome Biology and Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521, USA
Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, USA
These authors contributed equally to this work.
DNA methylation is an important epigenetic mark in many eukaryotes1, 2, 3, 4, 5. In plants, 24-nucleotide small interfering RNAs (siRNAs) bound to the effector protein, Argonaute 4 (AGO4), can direct de novo DNA methylation by the methyltransferase DRM2 (refs 2, 4–6). Here we report a new regulator of RNA-directed DNA methylation (RdDM) in Arabidopsis: RDM1. Loss-of-function mutations in the RDM1 gene impair the accumulation of 24-nucleotide siRNAs, reduce DNA methylation, and release transcriptional gene silencing at RdDM target loci. RDM1 encodes a small protein that seems to bind single-stranded methyl DNA, and associates and co-localizes with RNA polymerase II (Pol II, also known as NRPB), AGO4 and DRM2 in the nucleus. Our results indicate that RDM1 is a component of the RdDM effector complex and may have a role in linking siRNA production with pre-existing or de novo cytosine methylation. Our results also indicate that, although RDM1 and Pol V (also known as NRPE) may function together at some RdDM target sites in the peri-nucleolar siRNA processing centre, Pol II rather than Pol V is associated with the RdDM effector complex at target sites in the nucleoplasm.
