Extreme halophilic environments are the habitat of the archaeon Halobacterium salinarum. Anaerobic pressure leads to the expression of the integral membrane protein bacteriorhodopsin (BR). As a light-driven proton pump it exemplifies a vectorial catalysis which is optimized for ATP-synthesis. BR is ordered to two‑dimensional crystalline hexagonal structure: the Purple Membrane (PM). For biotechnical applications on surfaces and the construction of hybrid structures a specific monolayered orientation must be achieved. Therefore specific genetic modifications of BR are necessary.
