7 research outputs found
The directed cooperative assembly of proteorhodopsin into 2D and 3D polarized arrays
Proteorhodopsin is the membrane protein used by marine bacterioplankton as a light-driven proton pump. Here, we describe a rapid cooperative assembly process directed by universal electrostatic interactions that spontaneously organizes proteorhodopsin molecules into ordered arrays with well defined orientation and packing density. We demonstrate the charge density-matching mechanism that selectively controls the assembly process. The interactions among different components in the system are tuned by varying their charge densities to yield different organized transmembrane protein arrays: (i) a bacteriorhodopsin purple membrane-like structure where proteorhodopsin molecules are cooperatively arranged with charged lipids into a 2D hexagonal lattice; (ii) selected liquid-crystalline states in which crystalline lamellae made up of the coassembled proteorhodopsin and charged lipid molecules are coupled three-dimensionally with polarized proteorhodopsin orientation persisting through the macroscopic scale. Understanding this rapid electrostatically driven assembly process sheds light on organizing membrane proteins in general, which is a prerequisite for membrane protein structural and mechanistic studies as well as in vitro applications
Readers Letters
SMA-Lipodisq nanoparticles, with one bacteriorhodopsin
(bR) per
12 nm particle on average (protein/lipid molar ratio, 1:172), were
prepared without the use of detergents. Using pulsed and continuous
wave nitroxide spin label electron paramagnetic resonance, the structural
and dynamic integrity of bR was retained when compared with data for
bR obtained in the native membrane and in detergents and then with
crystal data. This indicates the potential of Lipodisq nanoparticles
as a useful membrane mimetic