Direct Evidence for Methyl Group Coordination by Carbon-Oxygen Hydrogen Bonds in the Lysine Methyltransferase SET7/9
Direct Evidence for Methyl Group Coordination by Carbon-Oxygen Hydrogen Bonds in the Lysine Methyltransferase SET7/9
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DOI：
10.1074/jbc.m111.232876
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发表时间：
2011-05-27
影响因子：
4.8
通讯作者：
Trievel, Raymond C.
中科院分区：
文献类型：
--
作者：
Horowitz, Scott;Yesselman, Joseph D.;Trievel, Raymond C.
SET结构域赖氨酸甲基转移酶（KMTs）是s -腺苷基蛋氨酸（AdoMet）依赖酶，催化组蛋白和非组蛋白中赖氨酸残基的位点特异性甲基化。基于晶体学和辅因子结合研究，提出了碳氧（CH中心点中心点中心点O）氢键来协调SET结构域活性位点内AdoMet和甲基赖氨酸的甲基。然而，由于x射线晶体结构中氢原子位置的不确定性，这些氢键的存在只是推断出来的。为了实验确定甲基氢原子的位置，我们使用NMR H-1化学位移结合量子力学计算来研究AdoMet甲基在人类KMT SET7/9活性位点的相互作用。我们的结果表明，AdoMet甲基上的三个氢原子中至少有两个参与了CH中心点中心点中心点O氢键。这些发现提供了在SET结构域活性位点形成CH中心点中心点中心点O氢键的直接、定量证据，并表明这些相互作用在催化中起作用。此外，AdoMet结合的热力学分析表明，这些相互作用对于SET结构域酶之间的辅因子结合很重要。
SET domain lysine methyltransferases (KMTs) are S-adenosylmethionine (AdoMet)-dependent enzymes that catalyze the site-specific methylation of lysyl residues in histone and nonhistone proteins. Based on crystallographic and cofactor binding studies, carbon-oxygen (CH center dot center dot center dot O) hydrogen bonds have been proposed to coordinate the methyl groups of AdoMet and methyllysine within the SET domain active site. However, the presence of these hydrogen bonds has only been inferred due to the uncertainty of hydrogen atom positions in x-ray crystal structures. To experimentally resolve the positions of the methyl hydrogen atoms, we used NMR H-1 chemical shift coupled with quantum mechanics calculations to examine the interactions of the AdoMet methyl group in the active site of the human KMT SET7/9. Our results indicated that at least two of the three hydrogens in the AdoMet methyl group engage in CH center dot center dot center dot O hydrogen bonding. These findings represent direct, quantitative evidence of CH center dot center dot center dot O hydrogen bond formation in the SET domain active site and suggest a role for these interactions in catalysis. Furthermore, thermodynamic analysis of AdoMet binding indicated that these interactions are important for cofactor binding across SET domain enzymes.