Reference: Beddoe T, et al. (2004) A biophysical analysis of the tetratricopeptide repeat-rich mitochondrial import receptor, Tom70, reveals an elongated monomer that is inherently flexible, unstable, and unfolds via a multistate pathway. J Biol Chem 279(45):46448-54

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Abstract


Proteins destined for all submitochondrial compartments are translocated across the outer mitochondrial membrane by the TOM (translocase of the outer membrane) complex, which consists of a number of specialized receptor subunits that bind mitochondrial precursor proteins for delivery into the translocation channel. One receptor, Tom70, binds large, hydrophobic mitochondrial precursors. The current model of Tom70-mediated import involves multiple dimers of the receptor recognizing a single molecule of substrate. Here we show via a battery of biophysical and spectroscopic techniques that the cytosolic domain of Tom70 is an elongated monomer. Thermal and urea-induced denaturation revealed that the receptor, which unfolds via a multistate pathway, is a relatively unstable molecule undergoing major conformational change at physiological temperatures. The data suggest that the malleability of the monomeric Tom70 receptor is an important factor in mitochondrial import.

Reference Type
Journal Article | Research Support, Non-U.S. Gov't
Authors
Beddoe T, Bushell SR, Perugini MA, Lithgow T, Mulhern TD, Bottomley SP, Rossjohn J
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