Virtuelle (Nano) Welten: PDB Molecule of the Month 39: Lac Repressor

Proteins of the lac Operon

Lac repressor controls the synthesis of three proteins. Beta-galactosidase, shown here from PDB entry 1bgl, is the enzyme that performs the first step in the metabolism of lactose, breaking it in half into the simple sugars glucose and galactose. Galactoside acetyltransferase, shown here from PDB entry 1krv, is another enzyme that acts on sugars, but its role in lactose metabolism is not as clear. Lactose permease is a protein found in the membrane of the bacterium, through which it transports lactose to the interior. The structure of lactose permease has not been solved yet, and is the subject of intense study. The structure shown here is a model of a similar human sugar transporter, from PDB entry 1ja5.