Use of octyl beta-thioglucopyranoside in two-dimensional crystallization of membrane proteins

A great interest exists in producing and/or improving two-dimensional (2D) crystals of membrane proteins amenable to structural analysis by electron c rystallography, Here we report on the use of the detergent n-octyl beta -D- thioglucopyranoside in 2D crystallization trials of membrane proteins with radically different structures including FhuA from the outer membrane of Es cherichia coli, light-harvesting complex II from Rubrivivax gelatinosus, an d Photosystem I from cyanobacterium Synechococcus sp, We have analyzed by e lectron microscopy the structures reconstituted after detergent removal fro m lipid- detergent or lipid-protein- detergent micellar solutions containin g either only n-octyl beta -D-thioglucopyranoside or n-octyl beta -D-thiogl ucopyranoside in combination with other detergents commonly used in membran e protein biochemistry. This allowed the definition of experimental conditi ons in which the use of n-octyl beta -D-thioglucopyranoside could induce a considerable increase in the size of reconstituted membrane structures, up to several micrometers. An other important feature was that, in addition to reconstitution of membrane proteins into large bilayered structures, this thioglycosylated detergent also was revealed to be efficient in crystalliza tion trials, allowing the proteins to be analyzed in large coherent two-dim ensional arrays. Thus, inclusion of n-octyl beta -D-thioglucopyranoside in 2D crystallization trials appears to be a promising method for the producti on of large and coherent 2D crystals that will be valuable for structural a nalysis by electron crystallography and atomic force microscopy, (C) 2001 A cademic Press.