Format

Send to

Choose Destination
J Mol Biol. 2008 Feb 29;376(4):1076-90. doi: 10.1016/j.jmb.2007.12.027. Epub 2007 Dec 23.

Point mutations in membrane proteins reshape energy landscape and populate different unfolding pathways.

Author information

1
Biotechnology Center, University of Technology, Tatzberg 47, 01307 Dresden, Germany. sapra@biotec.tu-dresden.de

Abstract

Using single-molecule force spectroscopy, we investigated the effect of single point mutations on the energy landscape and unfolding pathways of the transmembrane protein bacteriorhodopsin. We show that the unfolding energy barriers in the energy landscape of the membrane protein followed a simple two-state behavior and represent a manifestation of many converging unfolding pathways. Although the unfolding pathways of wild-type and mutant bacteriorhodopsin did not change, indicating the presence of same ensemble of structural unfolding intermediates, the free energies of the rate-limiting transition states of the bacteriorhodopsin mutants decreased as the distance of those transition states to the folded intermediate states decreased. Thus, all mutants exhibited Hammond behavior and a change in the free energies of the intermediates along the unfolding reaction coordinate and, consequently, their relative occupancies. This is the first experimental proof showing that point mutations can reshape the free energy landscape of a membrane protein and force single proteins to populate certain unfolding pathways over others.

PMID:
18191146
PMCID:
PMC2742699
DOI:
10.1016/j.jmb.2007.12.027
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center