title: Interaction of divalent metal ions with human translocase of inner membrane of mitochondria Tim23.
abstract: 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. Tim23p, the core component of TIM23 complex, forms the import pore across the inner membrane and exerts a key function in the protein import. However, the interaction of divalent metal ions with Tim23p and the contribution in the interaction of presequence peptide with Tim23p are still unknown. Herein, we investigated the interaction of divalent metal ions with the intermembrane space domain of Tim23p (Tim23IMS) and the interaction of presequence peptides with Tim23IMS in presence of Ca(2+) ion by fluorescence spectroscopy in vitro. The static fluorescence quenching indicates the existence of strong binding between divalent metal ions and Tim23IMS. The order of the binding strength is Ca(2+), Mg(2+), Cu(2+), Mn(2+), and Co(2+) (from strong to weak). Moreover, the interaction of presequence peptides with Tim23IMS is weakened in presence of Ca(2+) ion, which implicates that Ca(2+) ion may play an important role in the protein import by TIM23 complex.
authors.affiliation: School of Physics Science, Department of Biophysics, Nankai University, Tianjin 300071, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.affiliation: School of Physics Science, Department of Biophysics, Nankai University, Tianjin 300071, PR China.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Physics Science, Department of Biophysics, Nankai University, Tianjin 300071, PR China.
authors.forename: Honghua
authors.initials: H
authors.lastname: Deng
authors.affiliation: School of Physics Science, Department of Biophysics, Nankai University, Tianjin 300071, PR China. Electronic address: shujieli@nankai.edu.cn.
authors.forename: Shu Jie
authors.initials: SJ
authors.lastname: Li
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D006801:Humans; D008274:Magnesium / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010455:Peptides / Q000378:metabolism; D000072417:Protein Domains; D021381:Protein Transport; D013050:Spectrometry, Fluorescence
chemical_list: D002413:Cations, Divalent; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010455:Peptides; C438387:TIMM23 protein, human; D003035:Cobalt; D008345:Manganese; D003300:Copper; D008274:Magnesium; D002118:Calcium
keywords: Divalent metal ions; Interaction; Mitochondria; Presequence; TIM23 complex; Tim23p