单醇谷氨素的功能是储存和运输组装在IscU支架蛋白上的[Fe2S2]集群
Priyanka Shakamuri1, Bo Zhang, Michael K Johnson
1Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602, USA.
Journal of the American Chemical Society
|September 12, 2012
概括
分子伴侣HscA和HscB显著加速铁硫从IscU转移到Grx5,这对于细菌铁硫组装至关重要. 这凸显了这些共同主管对于高效的体外研究的必要性.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 微生物学 微生物学
背景情况:
- 铁硫 (Fe-S) 集群是许多蛋白质的重要辅因子.
- 细菌中的铁硫集群 (ISC) 组装机械包括像IscU这样的支架蛋白和分子辅助器HscA和HscB.
- IscU 作为 Fe-S 集群组装的主要支架,HscA 和 HscB 促进了依赖 ATP 的集群转移.
研究的目的:
- 调查分子辅助体HscA和HscB在Fe-S集群从IscU转移到apo-Grx5.5中的作用.
- 量化由HscA/HscB/Mg-ATP介导的Fe-S集群转移的增速.
主要方法:
- 使用循环二极化 (CD) 光谱来监测[Fe(2) S(2) ](2+) 集群转移.
- 在没有和存在HscA/HscB/Mg-ATP的情况下,比较了从[Fe(2) S(2) ](2+) 结合的IscU到apo-Grx5的集群转移率.
- 确定了转移过程的第二阶段速率常数.
主要成果:
- 在存在HscA/HscB/Mg-ATP的情况下,观察到[Fe(2) S(2) ](2+) 集群转移率的700倍增强.
- 在23°C时计算出20,000 M-1 min-1的二次速率常数,用于HscA/HscB介导的转移.
- 证明HscA和HscB对于高效的ATP依赖的[Fe(2) S(2) ](2+) 集群从IscU转移到Grx5.5是不可或缺的.
结论:
- HscA和HscB对于有效的依赖ATP的[Fe(2) S(2) ](2+) 集群从IscU转移到Grx5.5至关重要.
- 单醇谷氨素 (Grx's) 可能在存储和运输组装在 IscU 上的 Fe-S 集群中发挥作用.
- 在体外对[Fe(2) S(2) ](2+) -IscU集群转移的研究需要包括HscA/HscB辅助系统来进行准确的解释.
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