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The lactose operon (lac operon) is an operon required for the transport and metabolism of lactose in E. coli and many other enteric bacteria.Although glucose is the preferred carbon source for most enteric bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available through the activity of β-galactosidase. [1]
E. coli is a gram-negative, facultative anaerobe, nonsporulating coliform bacterium. [18] Cells are typically rod-shaped, and are about 2.0 μm long and 0.25–1.0 μm in diameter, with a cell volume of 0.6–0.7 μm 3. [19] [20] [21] E. coli stains gram-negative because its cell wall is composed of a thin peptidoglycan layer and an outer membrane.
The enzyme's role in the classical E.coli lac operon remains unclear. [1] [3] However, the enzyme's cellular role may be to detoxify non-metabolizable pyranosides by acetylating them and preventing their reentry into the cell. [1] [4]
E. coli SOS System: DNA can be damaged by cross-linking agents, UV irradiation, alkylating agents, etc. Once damaged, RecA, a LexA protease, senses that damaged DNA and becomes activated by removing its repressor. Once the LexA dimer repressor is removed, the expression of LexA operon is autoregulatory.
Galactoside permease is a protein coded by the lacY gene of the lac operon, and is found bound to the membrane of a cell for the purpose of binding galactoside molecules that have been solubilized. The protein is part of a system whose main function is to catalyze the accumulation and transport of lactose and other beta-galactosides across the ...
The first natural gene circuit studied in detail was the lac operon. In studies of diauxic growth of E. coli on two-sugar media, Jacques Monod and Francois Jacob discovered that E.coli preferentially consumes the more easily processed glucose before switching to lactose metabolism. They discovered that the mechanism that controlled the ...
One of the important occurrences of glycoside hydrolases in bacteria is the enzyme beta-galactosidase (LacZ), which is involved in regulation of expression of the lac operon in E. coli.
It is encoded by the lacY gene in the lac operon. The LacY gene is a component of the lac operon that encodes lactose permease, a protein responsible for breaking down lactose into glucose and galactose, alongside transacetylase and beta galactosidase.