Mechanisms of Biotin Transport

Biotin is an important micronutrient widely employed as an enzyme cofactor in all living organisms, therefore, cells that cannot synthesize biotin de novo must import it from the external environment. However, most cells have evolved a specific transport protein to facilitate biotin entry into cells, even if they have the necessary biosynthetic pathways, as it is more energetically efficient to scavenge biotin from the environment. The best-characterized examples of biotin transporters now belong to the bacterial energy coupling factor (ECF) family of vitamin transporters that employ similar but distinct mechanisms of solute uptake to the well studied ABC transporters. Here we review recent studies that shed new light on the structure and function of these important proteins. Studies on biotin transporters from organisms outside the bacterial kingdom are also presented, such as the analogous proteins from yeast, mammals and plants. However, there is a paucity of new information here compared to the ECF examples. Possible applications for exploiting biotin transporters for drug delivery are also examined.Al Azhar, Grant W. Booker, and Steven W. Polya