Bacterial rhodopsins and their potential use in biotechnology

Abstract

Halobacteria sense and transduce light energy with four retinal proteins occurring in their cell membrane. Bacteriorhodopsin is a light-driven proton pump and mediates photosynthetic growth of the cells. Halorhodopsin is a light-driven chloride pump and acts as an accessory pigment for net salt uptake during growth. Sensory rhodopsin and phoborhodopsin (P4gq mediate attraction to green light and repulsion by blue light via a signal chain regulating the flagellar motor response and allow the cell to find optimal environment for photosynthesis. Main emphasis will be put on the description of the molecular properties of the retinal proteins and the signal chain of the cell, but the potential use in biotechnology will also be summarized. This includes solar energy conversion, desalination, biosensors, light-triggered switches and optical storage.