Unfolding of heptameric co-chaperonin protein follows "fly casting" mechanism: observation of transient nonnative heptamer |
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Authors: | Perham Michael Chen Mingzhi Ma Jianpeng Wittung-Stafshede Pernilla |
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Affiliation: | Department of Chemistry, Rice University, Houston, Texas 77030, USA. |
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Abstract: | Protein recognition and binding play a fundamental role in living systems but sometimes also result in pathological aggregates. To probe the coupling between folding and binding in a homoheptameric system, we have characterized the time-resolved unfolding/disassembly mechanism of human co-chaperonin protein 10 (cpn10) by a combination of experimental and computational methods. The results from both approaches are in excellent agreement and make obvious that the kinetic process is three-state: an initial polypeptide-unfolding step, resulting in a non-native heptamer, is followed by a slower heptamer-dissociation step. This demonstrates that the barriers on the kinetic free-energy landscape are defined by thermodynamic stability. cpn10 is one of few, and the only heptameric, experimentally characterized system that follows the "fly casting scenario" of molecular recognition. |
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