Background: Streptococcus pneumoniaeis a leading cause of human respiratory tract infection. Despite the lack of activities of antioxidative enzymes, including cytochromes, hemoproteins, and peroxidases/catalases, traits conferring the aerotolerant-anaerobic growth of this bacterium are conserved, with the high efficacy of antioxidative actions, in an oxygen-rich environment.

Objective: Through proteome analysis, this study's intention was to evaluate differentially expressed proteins and/or gene products modeled in a highly virulent strain, S. pneumoniae D39, exogenously- treated with millimolar concentrations of H₂O₂.

Methods: For two-dimensional gel electrophoresis (2-DE) analysis, following one dimensional isoelectric focusing with an immobilized pH gradient of pH 4-7, the most significantly mobilized proteins expressed were separated by SDS-PAGE in the second dimension. With a total of 431 protein spots detected, certain proteins were excised, in-gel trypsin digested, and analyzed by combination with MALDI-TOF and LC-ESI-MS/MS for mass spectrometric peptide mapping and protein identification. Utilizing mass spectrometry analysis of spots excised from 2-DE, the selected protein spots were identified with a variety of databases and MASCOT.

Results: With the aid of comparisons to proteome reference maps, the most differentially expressed 38 proteins, those with approximately 1.4-fold or more increase and/or decrease or with multiple isoforms exhibiting variable pI values, were induced by treatment of exogenous 2 mM H₂O₂.The identified proteins were seen to be involved in pneumococcal pathogenesis and primary metabolism, amongst others.

Conclusion: This is the first study to convincingly document proteomic information associated with pathophysiological adaptation under the given oxidative conditions, and corresponding potential antioxidative mechanisms, in S. pneumoniae.

背景：肺炎链球菌是人类呼吸道感染的主要原因。尽管缺乏抗氧化酶的活性，包括细胞色素、血红素蛋白和过氧化物酶/过氧化氢酶，但在富氧环境中，赋予这种细菌耐氧-厌氧生长的特征是保守的，具有高效的抗氧化作用。

目的：通过蛋白质组分析，本研究的目的是评估以高毒力菌株肺炎链球菌 D39 为模型的差异表达蛋白质和/或基因产物，用毫摩尔浓度的 H ₂ O ₂外源处理。

方法：对于二维凝胶电泳 (2-DE) 分析，在固定化 pH 梯度为 pH 4-7 的情况下进行一维等电聚焦后，通过 SDS-PAGE 在二维中分离表达最显着的移动蛋白。共检测到 431 个蛋白质点，切除某些蛋白质，凝胶内胰蛋白酶消化，并结合 MALDI-TOF 和 LC-ESI-MS/MS 进行质谱肽图分析和蛋白质鉴定。利用从 2-DE 切下的点的质谱分析，选定的蛋白质点通过各种数据库和 MASCOT 进行鉴定。

结果：在与蛋白质组参考图比较的帮助下，表达差异最大的 38 种蛋白质，即那些具有大约 1.4 倍或更多增加和/或减少或具有表现出可变 pI 值的多个同种型的蛋白质，是通过外源性 2 mM H 处理诱导的₂ O ₂。所鉴定的蛋白质被认为与肺炎球菌的发病机制和初级代谢等有关。

结论：这是第一项令人信服地记录肺炎链球菌在给定氧化条件下与病理生理适应相关的蛋白质组学信息的研究，以及相应的潜在抗氧化机制。