Pivotal role of AtSUVH2 in heterochromatic histone methylation and gene silencing in Arabidopsis
Pivotal role of AtSUVH2 in heterochromatic histone methylation and gene silencing in Arabidopsis
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DOI：
10.1038/sj.emboj.7600604
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发表时间：
2005-04-06
期刊：
影响因子：
11.4
通讯作者：
Reuter, G
中科院分区：
文献类型：
--
作者：
Naumann, K;Fischer, A;Reuter, G
SU（VAR）3-9样组蛋白甲基转移酶控制真核生物中的异染色质结构域。在拟南芥中，10个SUVH基因编码SU（VAR）3-9同源物，其中SUVH 1、SUVH 2和SUVH 4（KRYPTONITE）代表SUVH基因的不同亚组。SUVH 1和SUVH 4的缺失导致异染色质组蛋白H3 K9二甲基化的微弱减少，而在SUVH 2缺失植物中，单-和二甲基H3 K9、单-和二甲基H3 K27以及单甲基H4 K20，拟南芥异染色质的组蛋白甲基化标记显著减少。与动物SU（VAR）3-9蛋白一样，SUVH 2显示出强烈的剂量依赖性作用。功能丧失抑制基因沉默，而过度表达增强基因沉默，导致异位异染色质化和显著的生长缺陷。此外，SUVH 2对转基因沉默的修饰部分传递给后代植物。这种表观遗传稳定性与DNA甲基化的可遗传变化相关。SUVH 2的突变解剖表明其N-末端和YDG结构域在指导DNA甲基化至靶序列中的作用，这是连续组蛋白甲基化的先决条件。SUVH 2的基因沉默依赖于MET 1和DDM 1，而不是CMT 3。在拟南芥中，具有组蛋白H3 K9和H4 K20甲基化活性的SUV H2在异染色质基因沉默中起核心作用。
SU(VAR)3-9 like histone methyltransferases control heterochromatic domains in eukaryotes. In Arabidopsis, 10 SUVH genes encode SU( VAR) 3-9 homologues where SUVH1, SUVH2 and SUVH4 ( KRYPTONITE) represent distinct subgroups of SUVH genes. Loss of SUVH1 and SUVH4 causes weak reduction of heterochromatic histone H3K9 dimethylation, whereas in SUVH2 null plants mono- and dimethyl H3K9, mono- and dimethyl H3K27, and monomethyl H4K20, the histone methylation marks of Arabidopsis heterochromatin are significantly reduced. Like animal SU( VAR) 3-9 proteins SUVH2 displays strong dosage-dependent effects. Loss of function suppresses, whereas overexpression enhances, gene silencing, causes ectopic heterochromatization and significant growth defects. Furthermore, modification of transgene silencing by SUVH2 is partially transmitted to the offspring plants. This epigenetic stability correlates with heritable changes in DNA methylation. Mutational dissection of SUVH2 indicates an implication of its N-terminus and YDG domain in directing DNA methylation to target sequences, a prerequisite for consecutive histone methylation. Gene silencing by SUVH2 depends on MET1 and DDM1, but not CMT3. In Arabidopsis, SUVH2 with its histone H3K9 and H4K20 methylation activity has a central role in heterochromatic gene silencing.