Bacteriorhodopsin acts as a light-driven proton pump, meaning that it uses energy from light to move protons across the cell membrane, creating an electrochemical gradient. This gradient can then be used to generate ATP, the energy currency of the cell.
When light is absorbed by bacteriorhodopsin, the molecule undergoes a conformational change, which results in the movement of protons across the membrane. The movement of protons generates an electrical potential across the membrane, which can be used to power ATP synthesis.
Haloarcula salinarum is able to thrive in environments with high salt concentrations, such as salt flats and salt lakes, and the ability to use light as a source of energy allows it to survive in these extreme environments.