Question

Explain what an activator is and how such proteins can regulate gene expression. You should include in your answer details of the genetic elements activators can bind to and outline two different molecular mechanisms by which activators can influence gene expression

Answer 1

ACTIVATORS AND THEIR FUNCTIONS

An activator is a transcription factor, which increases gene transcription of a gene or set of genes. Most of the activators are DNA-binding proteins that bind to enhancers or promoter-proximal elements.

Most activators function by binding sequence-specifically to a DNA site located near or in a promoter and making protein–protein interactions with the general transcription mechanism, thus facilitating the binding of the general transcription machinery to the promoter.

• The DNA site which is bound by the activator is known as "activator site".
• The part of the activator that makes protein–protein interactions with the general transcription machinery is referred as "activating region".
• The part of the general transcription machinery that makes protein–protein interactions with the activator is referred as "activation target”

Mechanisms

1. Activators increase the attraction of RNA polymerase for the promoter, via interactions with subunits of the RNA polymerase.
2. Activators can indirectly influence gene expression by altering the structure of the DNA.