To understand bacterial reactions to environmental stress or infection-related processes, it is necessary to identify the involved proteins. In mass spectrometry-based proteomics, the method of choice for spectra-to-peptide-match is database search, but in recent times, spectral libraries have come into focus. Here, we built a mass spectral library from Streptococcus pneumoniae D39, reflecting 76% of the theoretical proteome of the organism. Besides the proteins themselves, posttranslational protein modifications especially reveal central hubs of regulation in bacterial pathogenesis. Here, for example, phosphorylation events are involved in the signal transduction and regulation of virulence. Although there have been major advances in phosphoproteomics, identification of this modification is still challenging. To enhance the number of phosphorylated peptides, which can be reproducibly detected, a comprehensive mass spectral library of the S. pneumoniae D39 phosphoproteome has been compiled in addition to the comprehensive total proteome mass spectral library. The phosphopeptide library was manually validated, and the data quality was additionally proven by analyses of synthetic phosphorylated peptides. In total, 128 phosphorylated proteins were revealed, of which many are involved in glycolysis, purine metabolism, protein biosynthesis, and virulence. The publicly available, thoroughly validated spectral libraries are an excellent resource to improve and speed up future investigations on the proteome and phosphoproteome of pneumococci.

中文翻译：

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病原菌肺炎链球菌的综合光谱库，重点是磷酸蛋白。

为了了解细菌对环境压力或感染相关过程的反应，有必要鉴定涉及的蛋白质。在基于质谱的蛋白质组学中，谱图至肽段匹配的选择方法是数据库搜索，但近来，谱库已成为人们关注的焦点。在这里，我们从肺炎链球菌建立了一个质谱库D39，反映了该生物理论蛋白质组的76％。除蛋白质本身外，翻译后蛋白质修饰尤其揭示细菌发病机理中的调节中心。在此，例如，磷酸化事件涉及信号转导和毒力的调节。尽管磷酸化蛋白质组学已取得重大进展，但鉴定这种修饰仍然具有挑战性。为了增加可重复检测的磷酸化肽的数量，建立了肺炎链球菌的全面质谱库除全面的总蛋白质组质谱库外，还编辑了D39磷酸化蛋白质组。手动验证了磷酸肽库，并通过分析合成的磷酸化肽进一步证明了数据质量。总共揭示了128种磷酸化蛋白质，其中许多与糖酵解，嘌呤代谢，蛋白质生物合成和毒力有关。公开可用的，经过充分验证的光谱库是改善和加快对肺炎球菌的蛋白质组和磷酸化蛋白质组进行进一步研究的极好资源。