A WD40-repeat containing protein, similar to a fungal co-repressor, is required for transcriptional gene silencing in Chlamydomonas.
A WD40-repeat containing protein, similar to a fungal co-repressor, is required for transcriptional gene silencing in Chlamydomonas.
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衣藻转录基因沉默需要含有 WD40 重复序列的蛋白质，类似于真菌共阻遏物。
DOI：
10.1046/j.1365-313x.2002.01331.x
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Cerutti,Heriberto
中科院分区：
文献类型：
--
作者：
Zhang,Chaomei;Wu-Scharf,Dancia;Jeong,Byeong-ryool;Cerutti,Heriberto
在高等植物、哺乳动物和丝状真菌中，转录基因沉默经常与DNA甲基化有关。然而，最近的证据表明，某些转基因可以通过甲基化独立的机制失活。在单细胞绿藻-莱茵衣藻中，单拷贝转基因在转录上被沉默，而引入的DNA没有明显的胞嘧啶甲基化。我们已经分离出衣藻单胞菌基因Mut11，它是单拷贝转基因转录抑制所必需的。Mut11似乎在基因调控中具有全球作用，因为它也影响转座子的动员、细胞生长和对DNA损伤剂的敏感性。在瞬时表达分析中，预测的Mut11基因产物(Mut11p)和 Coliβ-葡萄糖醛酸苷酶之间的融合蛋白主要定位于细胞核。Mut11p是一种由370个氨基酸组成的多肽，含有7个WD40重复序列，与功能未知的蛋白质高度同源，这些蛋白质广泛分布于真核生物中。Mut11p还显示出与Tup1的C-末端结构域的相似性，Tup1是真菌中的一个全球转录共抑制因子。基于这些发现，我们推测，在衣藻中，某些单拷贝转基因和分散的转座子整合到常染色质区的沉默可能是通过一种类似于涉及全局转录抑制因子的机制(S)发生的。我们的结果也支持，在甲基化能力强的生物体中，存在一种独立于DNA甲基化的转录(反式)基因沉默机制(S)。
In higher plants, mammals, and filamentous fungi, transcriptional gene silencing is frequently associated with DNA methylation. However, recent evidence suggests that certain transgenes can be inactivated by a methylation independent mechanism. In the unicellular green algaChlamydomonas reinhardtii, single‐copy transgenes are transcriptionally silenced without discernible cytosine methylation of the introduced DNA. We have isolated aChlamydomonasgene,Mut11, which is required for the transcriptional repression of single‐copy transgenes.Mut11appears to have a global role in gene regulation since it also affects transposon mobilization, cellular growth, and sensitivity to DNA damaging agents. In transient expression assays, a fusion protein between the predictedMut11gene product (Mut11p) andE. coli β‐glucuronidase localizes predominantly to the nucleus. Mut11p, a polypeptide of 370 amino acids containing seven WD40 repeats, is highly homologous to proteins of unknown function that are widely distributed among eukaryotes. Mut11p also shows similarity to the C‐terminal domain of TUP1, a global transcriptional co‐repressor in fungi. Based on these findings we speculate that, inChlamydomonas, the silencing of certain single‐copy transgenes and dispersed transposons integrated into euchromatic regions may occur by a mechanism(s) similar to those involving global transcriptional repressors. Our results also support the existence, in methylation‐competent organisms, of a mechanism(s) of transcriptional (trans)gene silencing that is independent of DNA methylation.