Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States.
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600, United States.
J Proteome Res. 2024 Jan 5;23(1):71-83. doi: 10.1021/acs.jproteome.3c00323. Epub 2023 Dec 19.
Tyrosine sulfation in the Golgi of secreted and membrane proteins is an important post-translational modification (PTM). However, its labile nature has limited analysis by mass spectrometry (MS), a major reason why no sulfoproteome studies have been previously reported. Here, we show that a phosphoproteomics experimental workflow, which includes serial enrichment followed by high resolution, high mass accuracy MS, and tandem MS (MS/MS) analysis, enables sulfopeptide coenrichment and identification via accurate precursor ion mass shift open MSFragger database search. This approach, supported by manual validation, allows the confident identification of sulfotyrosine-containing peptides in the presence of high levels of phosphorylated peptides, thus enabling these two sterically and ionically similar isobaric PTMs to be distinguished and annotated in a single proteomic analysis. We applied this approach to isolated interphase and mitotic rat liver Golgi membranes and identified 67 tyrosine sulfopeptides, corresponding to 26 different proteins. This work discovered 23 new sulfoproteins with functions related to, for example, Ca-binding, glycan biosynthesis, and exocytosis. In addition, we report the first preliminary evidence for crosstalk between sulfation and phosphorylation in the Golgi, with implications for functional control.
蛋白质在高尔基体内的酪氨酸硫酸化是一种重要的翻译后修饰(PTM)。然而,由于其不稳定性,利用质谱(MS)进行分析受到限制,这也是之前没有进行过硫酸化蛋白质组学研究的主要原因。在这里,我们展示了一种磷酸化蛋白质组学实验工作流程,其中包括串联富集,随后进行高分辨率、高质量精度 MS 和串联 MS(MS/MS)分析,通过准确的前体离子质量偏移开放 MSFragger 数据库搜索实现硫酸肽共富集和鉴定。这种方法得到了手动验证的支持,能够在存在高水平磷酸化肽的情况下,鉴定出含有硫酸酪氨酸的肽,从而能够在单个蛋白质组学分析中区分和注释这两种空间和离子相似的等排修饰。我们将这种方法应用于分离的间期和有丝分裂大鼠肝高尔基膜,并鉴定出 67 个酪氨酸硫酸肽,对应 26 种不同的蛋白质。这项工作发现了 23 种新的硫酸化蛋白质,其功能与钙结合、聚糖生物合成和胞吐作用等有关。此外,我们还报告了高尔基体中硫酸化和磷酸化之间相互作用的初步证据,这对功能控制具有重要意义。