Identification of DIM-7, a protein required to target the DIM-5 H3 methyltransferase to chromatin
Identification of DIM-7, a protein required to target the DIM-5 H3 methyltransferase to chromatin
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DOI：
10.1073/pnas.1000328107
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发表时间：
2010-05-04
影响因子：
11.1
通讯作者：
Selker, Eric U.
中科院分区：
文献类型：
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作者：
Lewis, Zachary A.;Adhvaryu, Keyur K.;Selker, Eric U.
功能上不同的染色质结构域是通过组蛋白的不同翻译后修饰来描述的，在某些生物体中是通过 DNA 甲基化的差异来描述的。染色质结构域的正确建立和维护至关重要，但尚未得到充分理解。我们之前证明，丝状真菌粗糙脉孢菌中的异染色质由组蛋白 H3 (H3K9me3) 上的三甲基化赖氨酸 9 指导的胞嘧啶甲基化标记。 H3K9me3 是 DIM-5 赖氨酸甲基转移酶的产物，可被包含异染色质蛋白 1 和 DIM-2 DNA 甲基转移酶的蛋白质复合物识别。为了识别控制 DNA 甲基化和异染色质的建立和功能的其他成分，我们构建了一种含有两个可通过 DNA 甲基化沉默的可选择报告基因的菌株，并利用该菌株来选择 DNA 甲基化缺陷的突变体 (dim)。我们报告了一个先前未鉴定的基因 (dim-7)，它对于 H3K9me3 和 DNA 甲基化至关重要。 DIM-7 同源物仅存在于真菌中，并且差异很大。我们发现 DIM-7 在体内与 DIM-5 相互作用，并证明 DIM-7 N 末端附近的保守结构域是其稳定性所必需的。此外，我们发现 DIM-7 对于招募 DIM-5 形成异染色质至关重要。
Functionally distinct chromatin domains are delineated by distinct posttranslational modifications of histones, and in some organisms by differences in DNA methylation. Proper establishment and maintenance of chromatin domains is critical but not well understood. We previously demonstrated that heterochromatin in the filamentous fungus Neurospora crassa is marked by cytosine methylation directed by trimethylated Lysine 9 on histone H3 (H3K9me3). H3K9me3 is the product of the DIM-5 Lysine methyltransferase and is recognized by a protein complex containing heterochromatin protein-1 and the DIM-2 DNA methyltransferase. To identify additional components that control the establishment and function of DNA methylation and heterochromatin, we built a strain harboring two selectable reporter genes that are silenced by DNA methylation and employed this strain to select for mutants that are defective in DNA methylation (dim). We report a previously unidentified gene (dim-7) that is essential for H3K9me3 and DNA methylation. DIM-7 homologs are found only in fungi and are highly divergent. We found that DIM-7 interacts with DIM-5 in vivo and demonstrated that a conserved domain near the N terminus of DIM-7 is required for its stability. In addition, we found that DIM-7 is essential for recruitment of DIM-5 to form heterochromatin.