positive regulation of termination of RNA polymerase II transcription

Definition

Target type: biologicalprocess

Any process that activates or increases the frequency, rate or extent of termination of RNA polymerase II transcription. [GO_REF:0000058, GOC:TermGenie, PMID:25417108]

Positive regulation of termination of RNA polymerase II transcription involves a complex interplay of factors that control the transition from elongation to termination of gene transcription. It is a tightly regulated process that ensures proper mRNA processing and prevents aberrant transcripts from accumulating. Here is a detailed description of the biological process:

**1. Recognition of the Polyadenylation Signal:**
The process begins with the recognition of the polyadenylation signal (PAS) sequence (typically AAUAAA) within the nascent RNA transcript by a protein complex. This complex, known as the cleavage and polyadenylation specificity factor (CPSF), binds to the PAS and initiates the recruitment of other factors.

**2. Cleavage of the RNA Transcript:**
Once CPSF is bound, it recruits other factors, including cleavage stimulation factor (CstF), which recognizes a downstream GU-rich sequence. Together, these factors assemble a cleavage complex that cleaves the RNA transcript downstream of the PAS.

**3. Polyadenylation:**
After cleavage, the free 3' end of the RNA transcript is polyadenylated by poly(A) polymerase (PAP), which adds a string of adenine nucleotides (poly(A) tail) to the 3' end. This tail is essential for mRNA stability, nuclear export, and translation.

**4. Recruitment of the Termination Machinery:**
The cleavage and polyadenylation events trigger the recruitment of the termination machinery. This machinery includes the RNA polymerase II (RNAP II) C-terminal domain (CTD) phosphatase, which dephosphorylates the Ser2 residues within the CTD. Dephosphorylation of the CTD is a key signal for termination, causing RNAP II to detach from the DNA template.

**5. Transcription Termination:**
As RNAP II detaches, it encounters a specific termination signal (e.g., a hairpin structure in the nascent transcript) that further facilitates termination. This signal triggers the dissociation of RNAP II from the DNA, effectively ending transcription.

**6. mRNA Processing:**
After termination, the newly synthesized mRNA undergoes a series of processing steps, including capping, splicing, and export to the cytoplasm. These steps ensure that the mRNA is correctly processed and translated into a functional protein.

**Positive Regulation:**
Positive regulation of termination of RNA polymerase II transcription involves factors that enhance or accelerate the termination process. These factors include:

* **Increased CTD phosphatase activity:** Enhanced activity of the CTD phosphatase leads to more rapid dephosphorylation of the RNAP II CTD, promoting termination.
* **Specific transcription factors:** Some transcription factors can directly promote termination by interacting with the termination machinery or by influencing the structure of the nascent transcript.
* **Post-translational modifications:** Modifications of the CTD or other factors can influence the termination process. For example, phosphorylation of specific residues within the CTD can promote termination.

**Overall, positive regulation of termination of RNA polymerase II transcription is crucial for ensuring efficient and accurate gene expression. This process ensures that only mature and functional mRNAs are produced, preventing the accumulation of aberrant transcripts that could lead to cellular dysfunction.**'
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