Zinc induced folding is essential for TIM15 activity as an mtHsp70 chaperone

TY - JOUR

T1 - Zinc induced folding is essential for TIM15 activity as an mtHsp70 chaperone

AU - Fraga, Hugo

AU - Papaleo, Elena

AU - Vega, Sonia

AU - Velazquez-Campoy, Adrián

AU - Ventura, Salvador

N1 - Copyright © 2012 Elsevier B.V. All rights reserved.

PY - 2013/1

Y1 - 2013/1

N2 - Background: TIM15/Zim17 in yeast and its mammalian ortholog Hep are Zn 2 + finger (Cys4) proteins that assist mtHsp70 in protein import into the mitochondrial matrix. Methods: Here we characterized the Zn2 + induced TIM15 folding integrating biophysical and computational approaches. Results: TIM15 folding occurs from an essentially unstructured conformation to a Zn2 +-coordinated protein in a fast and markedly temperature-dependent process. Moreover, we demonstrate unambiguously that Zn2 + induced TIM15 folding is essential for its role as mtHsp70 chaperone since in the unstructured apo state TIM15 does not bind to mtHsp70 and is unable to prevent its aggregation. Molecular dynamics simulations help to understand the crucial role of Zn2 + in promoting a stable and functional 3D architecture in TIM15. It is shown that the metal ion, through its coordinating cysteine residues, can mediate relevant long-range effects with the interaction interface for mtHsp70 coupling thus folding and function. Conclusions: Zn2 + induced TIM15 folding is essential for its function and likely occurs in mitochondrial matrix where high concentrations of Zn2 + were reported. General significance: The combination of experimental and computational approaches presented here provide an integrated structural, kinetic and thermodynamic view of the folding of a mitochondrial zinc finger protein, which might be relevant to understand the organelle import of proteins sharing this fold.

AB - Background: TIM15/Zim17 in yeast and its mammalian ortholog Hep are Zn 2 + finger (Cys4) proteins that assist mtHsp70 in protein import into the mitochondrial matrix. Methods: Here we characterized the Zn2 + induced TIM15 folding integrating biophysical and computational approaches. Results: TIM15 folding occurs from an essentially unstructured conformation to a Zn2 +-coordinated protein in a fast and markedly temperature-dependent process. Moreover, we demonstrate unambiguously that Zn2 + induced TIM15 folding is essential for its role as mtHsp70 chaperone since in the unstructured apo state TIM15 does not bind to mtHsp70 and is unable to prevent its aggregation. Molecular dynamics simulations help to understand the crucial role of Zn2 + in promoting a stable and functional 3D architecture in TIM15. It is shown that the metal ion, through its coordinating cysteine residues, can mediate relevant long-range effects with the interaction interface for mtHsp70 coupling thus folding and function. Conclusions: Zn2 + induced TIM15 folding is essential for its function and likely occurs in mitochondrial matrix where high concentrations of Zn2 + were reported. General significance: The combination of experimental and computational approaches presented here provide an integrated structural, kinetic and thermodynamic view of the folding of a mitochondrial zinc finger protein, which might be relevant to understand the organelle import of proteins sharing this fold.

KW - HSP70 Heat-Shock Proteins

KW - Mitochondria

KW - Mitochondrial Proteins

KW - Molecular Dynamics Simulation

KW - Protein Folding

KW - Protein Transport

KW - Saccharomyces cerevisiae

KW - Saccharomyces cerevisiae Proteins

KW - Zinc

U2 - 10.1016/j.bbagen.2012.10.002

DO - 10.1016/j.bbagen.2012.10.002

M3 - Journal article

C2 - 23063975

SN - 0304-4165

VL - 1830

SP - 2139

EP - 2149

JO - B B A - General Subjects

JF - B B A - General Subjects

IS - 1

ER -