Two GW Repeat Proteins Interact with Tetrahymena thermophila Argonaute and Promote Genome Rearrangement
Two GW Repeat Proteins Interact with Tetrahymena thermophila Argonaute and Promote Genome Rearrangement
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DOI：
10.1128/mcb.00076-09
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发表时间：
2009-09-15
影响因子：
5.3
通讯作者：
Gorovsky, Martin A.
中科院分区：
文献类型：
--
作者：
Bednenko, Janna;Noto, Tomoko;Gorovsky, Martin A.
在接合嗜热四膜虫时，在从种系基因组发育出新的体细胞基因组时发生大量DNA消除。小的，类似于28个核苷酸的扫描RNA（scnRNA）和Twi1p，Argonaute家族成员，介导H3K27me3和H3K9me3组蛋白H3修饰，导致异染色质形成和异染色质化生殖系限制序列的切除。在我们寻找参与发育DNA重排的新因素时，我们确定了两个Twi1p相互作用蛋白，Wag1p和CnjBp。这两种蛋白质都含有GW（甘氨酸和色氨酸）重复序列，这是其他生物体中几种Argonaute相互作用蛋白质的特征。Wag1p和CnjBp与Twi1p共定位在亲本大核中的接合早期和在后期发育阶段的新发育大核中。大约在DNA消除发生的时候，Wag1p在发育中的大核中形成多个核体，这些核体不与异染色质DNA消除结构共定位。对Delta WAG1、Delta CnjB和双Delta WAG1 Delta CnjB敲除菌株的分析表明，WAG1和CnjB基因需要一起缺失，以抑制特异性scnRNA的下调、DNA消除结构的形成和DNA切除。因此，Wag1p和CnjBp是四膜虫中RNA干扰介导的基因组重排中具有重叠功能的两个新参与者。
In conjugating Tetrahymena thermophila, massive DNA elimination occurs upon the development of the new somatic genome from the germ line genome. Small, similar to 28-nucleotide scan RNAs (scnRNAs) and Twi1p, an Argonaute family member, mediate H3K27me3 and H3K9me3 histone H3 modifications, which lead to heterochromatin formation and the excision of the heterochromatinized germ line-limited sequences. In our search for new factors involved in developmental DNA rearrangement, we identified two Twi1p-interacting proteins, Wag1p and CnjBp. Both proteins contain GW (glycine and tryptophan) repeats, which are characteristic of several Argonaute-interacting proteins in other organisms. Wag1p and CnjBp colocalize with Twi1p in the parental macronucleus early in conjugation and in the new developing macronucleus during later developmental stages. Around the time DNA elimination occurs, Wag1p forms multiple nuclear bodies in the developing macronuclei that do not colocalize with heterochromatic DNA elimination structures. Analyses of Delta WAG1, Delta CnjB, and double Delta WAG1 Delta CnjB knockout strains revealed that WAG1 and CnjB genes need to be deleted together to inhibit the downregulation of specific scnRNAs, the formation of DNA elimination structures, and DNA excision. Thus, Wag1p and CnjBp are two novel players with overlapping functions in RNA interference-mediated genome rearrangement in Tetrahymena.