Probing the energy landscape of the membrane protein bacteriorhodopsin
Research output: Contribution to journal › Research article › Contributed › peer-review
Contributors
Abstract
The folding and stability of transmembrane proteins is a fundamental and unsolved biological problem. Here, single bacteriorhodopsin molecules were mechanically unfolded from native purple membranes using atomic force microscopy and force spectroscopy. The energy landscape of individual transmembrane α helices and polypeptide loops was mapped by monitoring the pulling speed dependence of the unfolding forces and applying Monte Carlo simulations. Single helices formed independently stable units stabilized by a single potential barrier. Mechanical unfolding of the helices was triggered by 3.9-7.7 Å extension, while natural unfolding rates were of the order of 10-3 s-1. Besides acting as individually stable units, helices associated pairwise, establishing a collective potential barrier. The unfolding pathways of individual proteins reflect distinct pulling speed-dependent unfolding routes in their energy landscapes. These observations support the two-stage model of membrane protein folding in which α helices insert into the membrane as stable units and then assemble into the functional protein.
Details
Original language | English |
---|---|
Pages (from-to) | 871-879 |
Number of pages | 9 |
Journal | Structure |
Volume | 12 |
Issue number | 5 |
Publication status | Published - May 2004 |
Peer-reviewed | Yes |
Externally published | Yes |
External IDs
PubMed | 15130479 |
---|