How many polypeptides are in the core enzyme of RNA polymerase?

The core enzyme of RNA polymerase in bacteria typically consists of five polypeptide subunits, which come together to form the functional unit necessary for RNA synthesis. This core enzyme is comprised of two alpha (α) subunits, one beta (β) subunit, one beta prime (β') subunit, and one omega (ω) subunit.

When RNA polymerase associates with a sigma (σ) factor, it forms the holoenzyme, which is essential for initiating transcription at specific promoters. While the holoenzyme is critical for recognizing promoter regions, it is the core enzyme, with its five essential polypeptides, that is primarily responsible for carrying out the elongation of RNA during transcription.

This structure of the core enzyme allows it to perform its function effectively and signifies the standard assembly of bacterial RNA polymerases. Understanding this composition is crucial for grasping molecular mechanisms of transcription in prokaryotic organisms.