Controlling membrane protein folding using photoresponsive surfactant

2012-07-10Membrane proteins perform a number of roles in biological function. Membrane lipids can self assembly into numerous different phases in aqueous solution, including micelles, vesicles and lamellar phases. However, the phase properties of biological membranes are far more complex. Many membrane proteins require specific lipids to be present in the membrane to be fully active. Therefore, artificial membrane-like environments for protein folding are studied. Many approaches are developed to solve the membrane protein folding problems and based on manipulating the bilayer structures. Bacteriorhodopsin (bR) is the most widely studied membrane protein, consists of seven transmembrane helical segments and functions which can work as a proton pump in Halobacterium Salinarium. In the present study, the reversible control of bR conformation with simple light illumination provides a method to control membrane protein folding. The azobenzene-based photosurfactant undergoes a reversible photoisomerization upon illumination either visible (trans) or UV (cis) light. The trans isomer is relatively hydrophobic and planar than cis isomer. The phase behavior and bilayer structures are changed by the effect of photoresponsive surfactant. These strategies provide a convenient means to control membrane protein folding with light illumination