一个单一的外球氨基酸替代会激活一个类似于血红素的蛋白质的NO反应性
Therese Albert1, Natasha Pence2, Fangfang Zhong2
1Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health & Science University 3181 SW Sam Jackson Park Road Portland Oregon 97239 USA moennelo@ohsu.edu.
菌根细菌的血红素样蛋白 (HLPs) 清除氧化 (NO). 一种突变的细菌HLP形成了一个稳定的铁-酸盐复合体,揭示了对NO排毒机制的洞察力.
科学领域:
- 生物化学 生物化学
- 金属蛋白化学 金属蛋白化学
- 微生物学 微生物学
背景情况:
- 菌根细菌的血红素样蛋白 (HLPs) 对于巨细胞内的病原体生存至关重要.
- 它们的精确分子功能,特别是在氧化 (NO) 清理中,尚未完全理解.
- 高酸盐表现出与NO的独特反应性,每一个二铁中心消耗多个NO分子.
研究的目的:
- 通过对遥远的ortologs进行比较研究,调查蛋白质支架在HLP与NO的反应性中的作用.
- 为了描述NO清理途径中的新型中间体.
- 了解菌体中NO排毒的结构基础.
主要方法:
- 局部定向的突变发生,以在阿佐托巴克特维尼兰迪HLP (Avi-HLP) 中产生T47F突变.
- 光谱表征包括电子吸收,EPR,FTIR和共振拉曼光谱.
- 分析NO清理的反应中间体和最终产品.
主要成果:
- 在Avi-HLP中的T47F突变诱导了一个桥梁μ-oxo差异结构,类似于Mycobacterium kansasii HLP (Mka-HLP).
- 这种结构变化使得Avi-HLP能够与NO反应,形成化物和混合价值Fe (iii) Fe (ii) 集群.
- 一个稳定的,磁性合的Fe(iii) {FeNO}7星团被形成和特征,提供了对NO结合和转化的见解.
- 该研究表明,特定的氨基酸残留物,如Mka-HLP中的Phe 46,可能会调节铁的降解潜力和NO反应性.
结论:
- 高酸盐,特别是通过像μ-oxo桥这样的结构适应,在NO排毒中发挥着重要作用.
- 描述的Fe(iii) {FeNO}7集群代表了HLP的NO清理机制中的一个关键中间体.
- 来自不同物种的HLP的比较研究,在突变发生的帮助下,对于阐明蛋白质功能和开发详细的机制模型是有价值的.
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