Core enzyme

Definition

A core enzyme is the essential component of RNA polymerase that is responsible for the synthesis of RNA during transcription. This enzyme binds to DNA and catalyzes the formation of RNA strands by incorporating ribonucleotides in a sequence determined by the DNA template. The core enzyme works in conjunction with various transcription factors to initiate and regulate the transcription process effectively.

5 Must Know Facts For Your Next Test

1. The core enzyme of bacterial RNA polymerase consists of five subunits: two alpha (α) subunits, one beta (β) subunit, one beta prime (β') subunit, and one omega (ω) subunit.
2. Core enzymes can associate with different sigma factors to form holoenzymes that initiate transcription at specific promoters.
3. In eukaryotes, core enzymes are part of larger RNA polymerase complexes (RNA polymerase I, II, III), each responsible for synthesizing different types of RNA.
4. The activity of the core enzyme is regulated by various transcription factors that can enhance or inhibit its function during transcription.
5. Core enzymes are crucial for the elongation phase of transcription, as they maintain the RNA synthesis process once it has been initiated.

Review Questions

• How does the core enzyme interact with sigma factors during the initiation of transcription?
  • The core enzyme interacts with sigma factors to form a holoenzyme that can recognize specific promoter regions on the DNA. The sigma factor guides the core enzyme to bind to the promoter by providing specificity for initiation, ensuring that transcription starts at the correct location. Once the holoenzyme is formed and transcription begins, the sigma factor may be released, allowing the core enzyme to proceed with RNA synthesis.
• Discuss the differences between the core enzymes of prokaryotic and eukaryotic RNA polymerases and their functional implications.
  • Prokaryotic core enzymes consist of five subunits and function as a single RNA polymerase, while eukaryotic core enzymes are part of more complex structures with multiple RNA polymerases (I, II, III), each dedicated to synthesizing specific types of RNA. This complexity in eukaryotes allows for more intricate regulation and coordination of gene expression compared to prokaryotes. Eukaryotic RNA polymerases require additional general transcription factors for initiation, reflecting their need to interact with a more complex chromatin environment.
• Evaluate the role of core enzymes in the context of gene expression regulation and how alterations in their function could impact cellular processes.
  • Core enzymes play a critical role in gene expression regulation by facilitating the synthesis of RNA from DNA templates. If their function is altered, such as through mutations or misregulation by transcription factors, it could lead to improper gene expression patterns. This disruption can have significant consequences for cellular processes including growth, differentiation, and response to environmental signals. Furthermore, understanding how these alterations impact cellular functions can provide insights into disease mechanisms and potential therapeutic targets.

Related terms

RNA polymerase: An enzyme that synthesizes RNA from a DNA template, playing a crucial role in the transcription process.

sigma factor:

A protein that associates with RNA polymerase to facilitate the initiation of transcription by helping the enzyme recognize specific promoter regions on the DNA.

promoter: A specific region of DNA where RNA polymerase binds to initiate transcription, often containing specific sequences recognized by transcription factors.