Introduction The profound importance for microorganisms to operate at a maximum efficiency has lead to adaptations allowing for groups of processes to be functional when resources are available, while on the contrary remaining “dormant” when not in need. This has been accomplished at the molecular level by configuring clusters of genes together on the genome into operons that elicit a processive response in the presence of a specific metabolite. The Lac operon is responsible for the cleaving of the disaccharide lactose into two products. A myriad of components control the expression of the Lac operon when two conditions are met. First, the substrate, lactose, must be present. Second, no better substrate for example, glucose, is present (2). The three structural genes in the Lac operon are lacZ, lacY, and lacA. The gene lacZ encodes the tetramer, ß-galactosidase, which is responsible for hydrolyzing the ß-1,4 glycosidic linkage between galactose and glucose in lactose. The transport of lactose into the cell via the enzyme lactose permease is encoded by the gene lacY. The lacA gene encodes the enzyme, galactoside transacetylase, a trimer that transfers an acetyl group from acetyl-CoA to galactosides. Activation of these genes is dependent on the activity of a promoter and three operators based on the nutritional and environmental conditions available to the cell.
The lac operon is a negatively controlled inducible operon that utilizes the product of the regulator gene lacI, to repress RNA polymerase from transcribing the lacZYA genes. The three operators involved in the lac operon: O1, O2, and O3 serve as binding sites for lacI and when bound repression is exhibited. Originally, the Jacob-Monod model of the Lac operon proposed only one operator existed. However, with the discovery of two additional operators (O2 and O3), Benno Müller-Hill and associates demonstrated