Bicelle size modulates the rate of bacteriorhodopsin folding. (25th April 2018)

• Record Type: Journal Article
• Authors: Gruenhagen, Timothy C.; Ziarek, Joshua J.; Schlebach, Jonathan P.
• Is Part Of: Protein science. Volume 27:Number 6(2018)
• Page Start: 1109
• Page End: 1112
• Publication Date: 2018-04-25
• Subjects: membrane protein folding -- folding kinetics -- bicelles -- micelles -- detergents; Proteins -- Periodicals; 572.6
• DOI: 10.1002/pro.3414
• Languages: English
• ISSNs: 0961-8368

Abstract

Abstract: The conformational equilibria of integral membrane proteins have proven extremely difficult to characterize within native lipid bilayers. To circumvent technical issues, investigations of the structure and stability of α‐helical membrane proteins are often carried out in mixed micelle or bicelle solvents that mimic the membrane and facilitate measurements of reversible folding. Under these conditions, the energetics of membrane protein folding are typically proportional to the mole fraction of an anionic detergent in the micelle. However, investigations of the folding and unfolding of bacteriorhodopsin (bR) surprisingly revealed that the folding rate is also highly sensitive to the bulk molar concentration of lipids and detergents. We show here that this rate enhancement coincides with changes in bicelle size and suggest this effect arises through restriction of the conformational search space during folding. In conjunction with previous mutagenic studies, these results provide additional evidence that a topological search limits the rate of bR folding. Furthermore, this finding provides insights into the manner by which micellar and bicellar environments influence the conformational stability of polytopic membrane proteins.