Modeling Hsp70-mediated Protein Folding

¹ Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
² Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH)

^* To whom correspondence should be addressed. E-mail: m.mayer{at}zmbh.uni-heidelberg.de.

Submitted on February 15, 2006
Revised on March 25, 2006
Accepted on 13 April 2006

	Abstract

The Hsp70 chaperone system is the major molecular chaperone system that assists protein-folding processes in all cells. To understand these processes, we analyzed the kinetic characteristics of the Escherischia coli homologues of this chaperone system during folding of a denatured protein using computer simulations and compared the results with in vitro refolding experiments. Rate constants used for the model were derived from recent literature or were determined here and scrutinized for their applicability to the refolding reaction. Our simulation results are consistent with laboratory experiments reported, not only simulating the refolding reaction of wild-type proteins but also the behavior of mutant variants. Variation of kinetic parameters and concentrations of components of the Hsp70 system demonstrate the robustness of the chaperone system in assisting protein folding. Furthermore, the importance of the synergistic stimulation of the ATPase activity of Hsp70 is demonstrated. The limitations of our kinetic model indicate sore spots in our understanding of this chaperone system. Our model provides a platform for further research on chaperone action and the mechanism of chaperone assisted refolding of denatured proteins.

Key Words: E-cell, Hsp70, Protein folding, chaperones, computer simulations, luciferase