Potential of light-harvesting proton pumps for bioenergy applications

Concerns about the security and longevity of traditional energy sources have increased interest in alternative methods of energy production, particularly those which utilize abundantly available solar energy. Solar energy can be harvested either indirectly through the conversion of plant or algal byproducts into biofuels or directly using engineered microorganisms. Here we summarize the main features of light-harvesting proton pumps, which may provide a relatively simple way to boost the efficiency of energy-limited biological processes in fuel production. This family of proton pumps, which includes bacteriorhodopsin and proteorhodopsin, directly uses light energy to create a proton motive force (pmf) which can be used by other enzymes to facilitate active transport, regulate transmembrane proteins, or to generate ATP and NADH.