Structure/Function Analysis of Recurrent Mutations in SETD2 Protein Reveals a Critical and Conserved Role for a SET Domain Residue in Maintaining Protein Stability and Histone H3 Lys-36 Trimethylation
Structure/Function Analysis of Recurrent Mutations in SETD2 Protein Reveals a Critical and Conserved Role for a SET Domain Residue in Maintaining Protein Stability and Histone H3 Lys-36 Trimethylation
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DOI：
10.1074/jbc.m116.739375
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发表时间：
2016-09-30
影响因子：
4.8
通讯作者：
Rathmell, W. Kimryn
中科院分区：
文献类型：
--
作者：
Hacker, Kathryn E.;Fahey, Catherine C.;Rathmell, W. Kimryn
酵母Set2组蛋白甲基转移酶是一种关键酶，在基因转录和DNA修复中起着许多关键作用。最近，人类同源物SETD2被发现在很大比例的肾细胞癌中反复突变，这提高了SETD2活性抑制肿瘤的可能性。利用出芽酵母和人类细胞系模型系统，我们检测了SETD2中两个进化上保守的残基在人类癌症中反复突变的功能意义。然而，其中一个位于Set2 Rpb1相互作用域的突变（R2510H）并未导致SETD2酶功能的明显缺陷，而该酶催化域的第二个突变（R1625C）导致组蛋白H3 Lys-36三甲基化（H3K36me3）的完全缺失。与野生型蛋白相比，该突变体表现出不变的热稳定性，但与组蛋白H3尾部的结合减少。令人惊讶的是，Set2中保守残基（R195C）的突变同样导致H3K36me3的完全丢失，但不影响酵母中二甲基化组蛋白h3lys -36 （H3K36me2）或与H3K36me2相关的功能。总的来说，这些数据表明Arg-1625在维持蛋白质与H3的相互作用以及该酶的特定H3K36me3功能方面发挥了关键作用，该酶从酵母到人类都是保守的。它们还可能为H3K36me3缺失如何导致基因组不稳定和癌症提供精细的生化解释。
The yeast Set2 histone methyltransferase is a critical enzyme that plays a number of key roles in gene transcription and DNA repair. Recently, the human homologue, SETD2, was found to be recurrently mutated in a significant percentage of renal cell carcinomas, raising the possibility that the activity of SETD2 is tumor-suppressive. Using budding yeast and human cell line model systems, we examined the functional significance of two evolutionarily conserved residues in SETD2 that are recurrently mutated in human cancers. Whereas one of these mutations (R2510H), located in the Set2 Rpb1 interaction domain, did not result in an observable defect in SETD2 enzymatic function, a second mutation in the catalytic domain of this enzyme (R1625C) resulted in a complete loss of histone H3 Lys-36 trimethylation (H3K36me3). This mutant showed unchanged thermal stability as compared with the wild type protein but diminished binding to the histone H3 tail. Surprisingly, mutation of the conserved residue in Set2 (R195C) similarly resulted in a complete loss of H3K36me3 but did not affect dimethylated histone H3 Lys-36 (H3K36me2) or functions associated with H3K36me2 in yeast. Collectively, these data imply a critical role for Arg-1625 in maintaining the protein interaction with H3 and specific H3K36me3 function of this enzyme, which is conserved from yeast to humans. They also may provide a refined biochemical explanation for how H3K36me3 loss leads to genomic instability and cancer.