西湖大学吴明轩小组近日取得一项新成果。经过不懈努力，他们的研究通过磺酸和色氨酸之间的单电子转移，使甲基赖氨酸读取器蛋白的位点选择性光交联成为可能。相关论文于2024年7月30日发表在《自然—化学》杂志上。

读取器蛋白是一类重要的蛋白质，可以识别特定位点的修饰残基，其发现对于揭示翻译后修饰的生物学作用至关重要。光反应交联剂是研究读取器蛋白的有力工具。然而，现有方法通常采用具有合成挑战性的光反应弹头，其辐照后产生的高能中间体，如亚硝烯和卡宾，可能会导致大量的非特异性交联。

有鉴于此，课题组报道了二甲基磺酸作为一种甲基赖氨酸模拟物，在紫外线照射下通过单电子转移与特定的读取器结合，随后与结合口袋内的保守色氨酸交联。交联依赖于蛋白质模板化的磺胺和吲哚之间的σ -π电子供体-受体相互作用，确保了色氨酸在活性位点的良好选择性，和与其他甲基赖氨酸读取器蛋白的正交性。这种方法可以从复杂的细胞样本中加速发现甲基赖氨酸读取器。此外，这种光交联策略可以扩展到开发其他类型的，微环境依赖的位点特异性色氨酸偶联。

附：英文原文

Title: Single-electron transfer between sulfonium and tryptophan enables site-selective photo crosslinking of methyllysine reader proteins

Author: Feng, Feng, Gao, Yingxiao, Zhao, Qun, Luo, Ting, Yang, Qingyun, Zhao, Nan, Xiao, Yihang, Han, Yusong, Pan, Jinheng, Feng, Shan, Zhang, Lihua, Wu, Mingxuan

Issue&Volume: 2024-07-30

Abstract: The identification of readers, an important class of proteins that recognize modified residues at specific sites, is essential to uncover the biological roles of post-translational modifications. Photoreactive crosslinkers are powerful tools for investigating readers. However, existing methods usually employ synthetically challenging photoreactive warheads, and their high-energy intermediates generated upon irradiation, such as nitrene and carbene, may cause substantial non-specific crosslinking. Here we report dimethylsulfonium as a methyllysine mimic that binds to specific readers and subsequently crosslinks to a conserved tryptophan inside the binding pocket through single-electron transfer under ultraviolet irradiation. The crosslinking relies on a protein-templated σ–π electron donor–acceptor interaction between sulfonium and indole, ensuring excellent site selectivity for tryptophan in the active site and orthogonality to other methyllysine readers. This method could escalate the discovery of methyllysine readers from complex cell samples. Furthermore, this photo crosslinking strategy could be extended to develop other types of microenvironment-dependent conjugations to site-specific tryptophan.

DOI: 10.1038/s41557-024-01577-y

Source: https://www.nature.com/articles/s41557-024-01577-y