holoenzyme

Examples of holoenzyme in the following topics:

• Prokaryotic Transcription and Translation Are Coupled

  • RNA polymerase (RNAP) binds to one of several specificity factors, σ, to form a holoenzyme.
  • This holoenzyme/wound-DNA structure is referred to as the closed complex.
  • This holoenzyme/unwound-DNA structure is called the open complex.
  • The RNA polymerase transcribes the DNA (the beta subunit initiates the synthesis), but produces about 10 abortive (short, non-productive) transcripts which are unable to leave the RNA polymerase because the exit channel is blocked by the σ-factor.The σ-factor eventually dissociates from the holoenzyme, and elongation proceeds.
  • Additional transcription regulation comes from transcription factors that can affect the stability of the holoenzyme structure at initiation.

• Initiation of Transcription in Prokaryotes

  • The polymerase comprised of all five subunits is called the holoenzyme.

• Cofactors and Energy Transitions

  • An inactive enzyme without the cofactor is called an apoenzyme, while the complete enzyme with cofactor is the holoenzyme.