四膜虫金属硫蛋白 MTT1 和 MTT2 的功能比较。
Functional comparison of metallothioneins MTT1 and MTT2 from Tetrahymena thermophila.
机构信息
Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan 030006, PR China.
出版信息
Arch Biochem Biophys. 2011 May 15;509(2):170-6. doi: 10.1016/j.abb.2011.02.015. Epub 2011 Feb 23.
Metallothioneins MTT1 and MTT2 from Tetrahymena thermophila have been characterized. The MTT1 contains mainly characteristic Cys-Cys-Cys and Cys-Cys clusters, but MTT2 contains mainly Cys-X-Cys cluster. Cd(16)-MTT1 mainly consists of α-helix and β-turns, in contrast, Cd(11)-MTT2 mainly consists of random coils. Reaction of Cd(16)-MTT1 and Cd(11)-MTT2 with nitric oxide leads to intramolecular disulfide bond formation, respectively. Binding stabilities of Cd(2+), Hg(2+) and Zn(2+) to MTT1 are stronger than those to MTT2. Cu(2+) can not replace Cd(2+) from Cd(16)-MTT1 complex, but can replace Cd(2+) from Cd(11)-MTT2 complex. The analysis of qRT-PCR revealed MTT2 mRNA levels were 31-fold higher than those of MTT1 under basal conditions. These results further suggest MTT1 possibly play a role in the detoxification of heavy metal ions, and MTT2 may be involved in the homeostasis of copper ions.
嗜热四膜虫金属硫蛋白 MTT1 和 MTT2 的特性已被阐明。MTT1 主要含有特征性的 Cys-Cys-Cys 和 Cys-Cys 簇，但 MTT2 主要含有 Cys-X-Cys 簇。Cd(16)-MTT1 主要由α-螺旋和β-转角组成，而 Cd(11)-MTT2 主要由无规卷曲组成。与一氧化氮反应后，Cd(16)-MTT1 和 Cd(11)-MTT2 分别形成分子内二硫键。MTT1 与 Cd(2+)、Hg(2+)和 Zn(2+)的结合稳定性强于 MTT2。Cu(2+)不能从 Cd(16)-MTT1 配合物中取代 Cd(2+)，但可以从 Cd(11)-MTT2 配合物中取代 Cd(2+)。qRT-PCR 分析显示，在基础条件下，MTT2mRNA 的水平比 MTT1 高 31 倍。这些结果进一步表明，MTT1 可能在重金属离子解毒中发挥作用，而 MTT2 可能参与铜离子的动态平衡。
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