Department of Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, 90033, CA, USA.
Department of Physics and Astronomy, California State University, Los Angeles, 5151 State University Drive, Los Angeles, 90033, CA, USA.
Arch Biochem Biophys. 2021 Feb 15;698:108716. doi: 10.1016/j.abb.2020.108716. Epub 2020 Dec 10.
The effects of phosphorylation of histone H3 at serine 10 have been studied in the context of other posttranslational modifications such as lysine methylation. We set out to investigate the impact of phosphoserine-10 on arginine-8 methylation. We performed methylation reactions using peptides based on histone H3 that contain a phosphorylated serine and compared the extent of arginine methylation with unmodified peptides. Results obtained via fluorography indicate that peptides containing a phosphorylated serine-10 inhibit deposition of methyl groups to arginine-8 residues. To further explore the effects of phosphoserine on neighboring arginine residues, we physically characterized the non-covalent interactions between histone H3 phosphoserine-10 and arginine-8 using P NMR spectroscopy. A salt bridge was detected between the negatively charged phosphoserine-10 and the positively charged unmodified arginine-8 residue. This salt bridge was not detected when arginine-8 was symmetrically dimethylated. Finally, molecular simulations not only confirm the presence of a salt bridge but also identify a subset of electrostatic interactions present when arginine is replaced with alanine. Taken together, our work suggests that the negatively charged phosphoserine maximizes its interactions. By limiting its exposure and creating new contacts with neighboring residues, it will inhibit deposition of neighboring methyl groups, not through steric hindrance, but by forming intrapeptide interactions that may mask substrate recognition. Our work provides a mechanistic framework for understanding the role of phosphoserine on nearby amino acid residues and arginine methylation.
组蛋白 H3 丝氨酸 10 位磷酸化的影响已经在其他翻译后修饰（如赖氨酸甲基化）的背景下进行了研究。我们着手研究磷酸丝氨酸-10 对精氨酸-8 甲基化的影响。我们使用含有磷酸丝氨酸的组蛋白 H3 肽进行甲基化反应，并将精氨酸甲基化的程度与未修饰的肽进行比较。荧光成像结果表明，含有磷酸丝氨酸-10 的肽抑制了精氨酸-8 残基上甲基的沉积。为了进一步探讨磷酸丝氨酸对邻近精氨酸残基的影响，我们使用 P NMR 光谱学对组蛋白 H3 磷酸丝氨酸-10 和精氨酸-8 之间的非共价相互作用进行了物理表征。在带负电荷的磷酸丝氨酸-10 和带正电荷的未修饰的精氨酸-8 残基之间检测到盐桥。当精氨酸-8 被对称二甲基化时，未检测到盐桥。最后，分子模拟不仅证实了盐桥的存在，还确定了当精氨酸被丙氨酸取代时存在的一组静电相互作用。总之，我们的工作表明，带负电荷的磷酸丝氨酸最大限度地发挥其相互作用。通过限制其暴露并与邻近残基形成新的接触，它将抑制邻近甲基的沉积，不是通过空间位阻，而是通过形成可能掩盖底物识别的肽内相互作用。我们的工作为理解磷酸丝氨酸对附近氨基酸残基和精氨酸甲基化的作用提供了一个机制框架。
