微生物在它们对单核酶的化方面具有战略性差异
Sanjay Kumar Rohaun1, Ramakrishnan Sethu1, James A Imlay1
1Department of Microbiology, University of Illinois, Urbana, IL 61801.
概括
微生物将不同的金属纳入必要的酶中,以防止氧化损伤. 生物体的金属可用性,而不是酶,决定了金属的选择,影响了酶的功能.
科学领域:
- 生物化学 生物化学
- 微生物学 微生物学
- 酶动力学 酶动力学
背景情况:
- 非氧化碳Fe (II) 辅因子酶对活性氧物种的氧化敏感.
- 氧化应激可以使必要的酶失活,导致严重的生理后果.
- 大肠杆菌通过进口来抵消过氧化 (H2O2),以取代敏感酶中的铁.
研究的目的:
- 为了在各种微生物物种中研究金属辅因子,该金属辅因子被纳入了ribulose-5-phosphate 3-epimerase.
- 为了确定蛋白质序列或生物体的金属可用性是否决定金属的结合.
- 为了比较酶与不同金属辅助因子的催化周转率.
主要方法:
- 来自各种微生物 (例如大肠杆菌,细菌菌,细菌菌,细菌菌,乳球菌,细菌菌) 的金属合并在ribulose-5-phosphate 3-epimerase中的比较分析.
- 对另一种单核酶形酶进行检查,以检测金属辅因子的多样性.
- 异质表达实验,以评估宿主生物体的金属池与蛋白质序列对金属结合的影响.
主要成果:
- 细菌菌类的thetaiotaomicron包含铁,类似于大肠杆菌.
- 细菌细菌和乳球菌乳糖含有,而Saccharomyces cerevisiae含有.
- 异质表达揭示了生物体的金属池,而不是蛋白质,决定了合并的金属.
- 酶与铁的催化周转率最高,与的催化周转率最低,不论来源有机体.
结论:
- 微生物应对氧化应激的策略包括将或等金属纳入酶中,以取代敏感的铁辅因子.
- 生物体细胞环境中金属的可用性是辅因子结合的主要决定因素.
- 进化似乎受到其通过蛋白质序列修改改变金属辅助因子内在催化特性的能力的限制.
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