Developing New Isotope-Coded Mass Spectrometry-Cleavable Cross-Linkers for Elucidating Protein Structures
作者:Clinton Yu、Wynne Kandur、Athit Kao、Scott Rychnovsky、Lan Huang
DOI:10.1021/ac403636b
日期:2014.2.18
Structural characterization of protein complexes is essential for the understanding of their function and regulation. However, it remains challenging due to limitations in existing tools. With recent technological improvements, cross-linking mass spectrometry (XL-MS) has become a powerful strategy to define protein–protein interactions and elucidate structural topologies of protein complexes. To further advance XL-MS studies, we present here the development of new isotope-coded MS-cleavable homobifunctional cross-linkers: d0- and d10-labeled dimethyl disuccinimidyl sulfoxide (DMDSSO). Detailed characterization of DMDSSO cross-linked peptides further demonstrates that sulfoxide-containing MS-cleavable cross-linkers offer robust and predictable MS2 fragmentation of cross-linked peptides, permitting subsequent MS3 analysis for simplified, unambiguous identification. Concurrent usage of these reagents provides a characteristic doublet pattern of DMDSSO cross-linked peptides, thus aiding in the confidence of cross-link identification by MSn analysis. More importantly, the unique isotopic profile permits quantitative analysis of cross-linked peptides and therefore expands the capability of XL-MS strategies to analyze both static and dynamic protein interactions. Together, our work has established a new XL-MS workflow for future studies toward the understanding of structural dynamics of protein complexes.
蛋白质复合物的结构表征对于理解其功能和调节机制至关重要。然而,由于现有工具的局限性,这项工作仍然充满挑战。随着最近技术的进步,交联质谱(XL-MS)已成为定义蛋白质相互作用和阐明蛋白质复合物结构拓扑的一种有力策略。为了进一步推进XL-MS研究,我们在此介绍新型同位素编码的MS可裂解同源双功能交联剂:d0和d10标记的二甲基二琥珀酰亚胺基亚砜(DMDSSO)。对DMDSSO交联肽的详细表征进一步表明,含亚砜的MS可裂解交联剂能够对交联肽提供稳定且可预测的MS2碎片,从而允许后续的MS3分析,以进行简化且明确的鉴定。同时使用这些试剂可提供DMDSSO交联肽的特征双峰模式,从而有助于通过MSn分析提高交联鉴定的置信度。更重要的是,独特的同位素谱图允许对交联肽进行定量分析,从而扩展了XL-MS策略分析静态和动态蛋白质相互作用的能力。总之,我们的工作为未来研究建立了一种新的XL-MS工作流程,以了解蛋白质复合物的结构动力学。