Interaction of divalent metal ions with human translocase of inner membrane of mitochondria Tim50

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• 作者：Yongqiang Zhang^a ; ^b ; Honghua Deng^a ; Xinzheng Zhang^a ; Shu Jie Li^a ; ^{shujieli@nankai.edu.cn}
• 关键词：Mitochondria ; TIM23 complex ; Tim50 ; Presequence ; Divalent metal ions ; Interaction
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2012
• 出版时间：23 November, 2012
• 年：2012
• 卷：428
• 期：3
• 页码：365-370
• 全文大小：592 K

文摘

The preprotein translocase of the inner membrane of mitochondria (TIM23 complex) is the main entry gate for proteins of the matrix and the inner membrane. Tim50 is a major receptor for transporting the precursor protein across the mitochondrial inner membrane in TIM23 complex. However, the interaction of divalent metal ions with Tim50 and the contribution in the interaction of presequence peptide with Tim50 are still unknown. Herein, we investigated the interaction of divalent metal ions with the intermembrane space domain of Tim50 (Tim50_IMS) and the interaction of presequence peptides with Tim50_IMS in presence of Ca²⁺ ion by fluorescence spectroscopy in vitro. The static fluorescence quenching indicates the existence of strong binding between divalent metal ions and Tim50_IMS. The order of the binding strength is Ca²⁺, Mg²⁺, Cu²⁺, Mn²⁺, and Co²⁺ (from strong to weak). Moreover, the interaction of presequence peptides with Tim50_IMS is weakened in presence of Ca²⁺ ion, which implicates that Ca²⁺ ion may play an important role in the protein import by TIM23 complex.