Imaging Bacteriorhodopsin-Like Molecules Of Claret-Membranes From Tibet Halobacteria Xz515 By Atomic Force Microscope

Halobacteria H.sp.xz 515 was isolated from a salt lake in Tibet. Although proton release-and-uptake across claret membrane is in reverse order compared to bacteriorhodopsin in purple membrane from Halobacterium Sali-narum, and its efficiency of proton pump is much lower, AFM image shows that the molecules are still arranged in a two-dimensional hexagonal lattice of trimers. Primary structure of C- to G-helix of the archaerhodopsin shows that it has only 56% homology with bacteriorhodopsin. But the interactive amino acid residues at the interface between Band D-helixes are conserved. These amino acid residues are believed to play a significant role in the stability of protein oligomers.