Catabolite activator protein (CAP)

Definition

Catabolite Activator Protein (CAP) is a regulatory protein in bacteria that facilitates the transcription of certain genes by binding to DNA and enhancing RNA polymerase activity. It functions primarily in the presence of cyclic AMP (cAMP), which indicates low glucose levels.

5 Must Know Facts For Your Next Test

1. CAP binds to specific DNA sequences called CAP binding sites, usually located upstream of the promoter region.
2. The activity of CAP is regulated by cAMP, which binds to CAP and causes a conformational change allowing it to bind DNA.
3. In the lac operon, CAP-cAMP complex increases transcription when glucose levels are low and lactose is available.
4. CAP-cAMP complex assists RNA polymerase in binding more efficiently to the promoter region, thus facilitating gene transcription.
5. Mutations in the CAP binding site can significantly reduce or abolish transcriptional activation by CAP.

Review Questions

Related terms

cyclic AMP (cAMP):

A secondary messenger molecule that activates CAP by inducing a conformational change.

lac operon:

A set of genes involved in lactose metabolism whose expression is regulated by both lactose and glucose levels.

RNA polymerase:

An enzyme responsible for synthesizing RNA from a DNA template during transcription.