Analysis of peptides and proteins in their binding to GroEL
Article first published online: 1 SEP 2010
Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Journal of Peptide Science
Volume 16, Issue 12, pages 693–700, December 2010
How to Cite
Li, Y., Zheng, Z., Ramsey, A. and Chen, L. (2010), Analysis of peptides and proteins in their binding to GroEL. J. Peptide Sci., 16: 693–700. doi: 10.1002/psc.1288
- Issue published online: 23 NOV 2010
- Article first published online: 1 SEP 2010
- Manuscript Accepted: 27 JUL 2010
- Manuscript Revised: 13 JUL 2010
- Manuscript Received: 3 MAY 2010
- NIH. Grant Number: R01 GM065260
- substrate folding;
- molecular chaperon
The GroEL–GroES is an essential molecular chaperon system that assists protein folding in cell. Binding of various substrate proteins to GroEL is one of the key aspects in GroEL-assisted protein folding. Small peptides may mimic segments of the substrate proteins in contact with GroEL and allow detailed structural analysis of the interactions. A model peptide SBP has been shown to bind to a region in GroEL that is important for binding of substrate proteins. Here, we investigated whether the observed GroEL–SBP interaction represented those of GroEL–substrate proteins, and whether SBP was able to mimic various aspects of substrate proteins in GroE-assisted protein folding cycle. We found that SBP competed with substrate proteins, including α-lactalbumin, rhodanese, and malate dehydrogenase, in binding to GroEL. SBP stimulated GroEL ATP hydrolysis rate in a manner similar to that of α-lactalbumin. SBP did not prevent GroES from binding to GroEL, and GroES association reduced the ATPase rates of GroEL/SBP and GroEL/α-lactalbumin to a comparable extent. Binding of both SBP and α-lactalbumin to apo GroEL was dominated by hydrophobic interaction. Interestingly, association of α-lactalbumin to GroEL/GroES was thermodynamically distinct from that to GroEL with reduced affinity and decreased contribution from hydrophobic interaction. However, SBP did not display such differential binding behaviors to apo GroEL and GroEL/GroES, likely due to the lack of a contiguous polypeptide chain that links all of the bound peptide fragments. Nevertheless, studies using peptides provide valuable information on the nature of GroEL–substrate protein interaction, which is central to understand the mechanism of GroEL-assisted protein folding. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.