The lac repressor (LacI) is a DNA-binding protein that inhibits the expression of genes coding for proteins involved in the metabolism of lactose in bacteria. These genes are repressed when lactose is not available to the cell, ensuring that the bacterium only invests energy in the production of machinery necessary for uptake and utilization of ...

The lactose repressor protein (LacI), the prototype for genetic regulatory proteins, controls expression of lactose metabolic genes by binding to its cognate operator sequences in E. coli DNA. Inducer binding elicits a conformational change that diminishes affinity for operator sequences with no eff …

Feb 17, 1996 · Crystal structure of the lactose operon repressor and its complexes with DNA and inducer. The lac operon of Escherichia coli is the paradigm for gene regulation. Its key component is the lac repressor, a product of the lacI gene.

Jun 29, 2021 · We explore a deep mutational scanning study that measured the transcriptional repression function of 43,669 variants of the Escherichia coli LacI protein. We analyze structural and evolutionary aspects that relate to how the function of this protein is maintained, including an in-depth look at the C-terminal domain.

Jul 8, 2013 · A single mutation, W220F, in the inducer-binding site of LacI generates a fully functional repressor (named LacI WF) with a 100-fold wider dynamic range at 37°C and a 10-fold decrease in leakiness under all conditions tested. The reduction in leakiness results in unimpaired growth when toxic proteins are cloned under the control of the mutant ...

Jan 17, 2006 · A key to controlling the operon is the DNA-binding protein called the lac repressor (LacI), shown on the left. In the absence of lactose, LacI inhibits the expression of the operon by binding to two out of three operator sites and causing …

The lac repressor protein: molecular shape, subunit structure, and proposed model for operator interaction based on structural studies of microcrystals

The lac operon of E. coli is the hypothesis for gene regulation; the key component is the lacI repressor. The uncontrolled-type DNA sequence of lac operon has three lac repressor recognition sites in a stretch of 500 base pairs. It also has a binding site for catabolite activator proteins (CAP), which is considered to be an activator.

Mar 1, 1996 · The crystallographic structure of the complex with DNA suggests that the tetrameric repressor functions synergistically with catabolite gene activator protein (CAP) and participates in the quaternary formation of repression loops in which one tetrameric repressor interacts simultaneously with two sites on the genomic DNA.

Repressor of the lactose operon. Binds allolactose as an inducer. Removing residues 1-59 results in loss of DNA-binding activity but retains tetrameric structure and inducer-binding activity.