DNA-templated transcription termination

Definition

Target type: biologicalprocess

The completion of transcription: the RNA polymerase pauses, the RNA-DNA hybrid dissociates, followed by the release of the RNA polymerase from its DNA template. [GOC:txnOH, PMID:15020047, PMID:18280161, PMID:30978344]

DNA-templated transcription termination is the process by which RNA polymerase, the enzyme responsible for transcribing DNA into RNA, is instructed to detach from the DNA template and cease RNA synthesis. This intricate process is essential for proper gene expression and regulation, ensuring that the correct amount of RNA is produced for each gene.

Here is a detailed description of the process:

**1. Recognition of Termination Signals:** Transcription termination is initiated by specific DNA sequences known as termination signals. These signals are recognized by RNA polymerase and trigger the termination process.

**2. Formation of a Hairpin Structure:** Many termination signals include a sequence that is rich in guanine and cytosine (G-C) nucleotides. Upon transcription, this sequence forms a stable hairpin loop structure in the newly synthesized RNA molecule. This hairpin structure acts as a physical barrier that slows down RNA polymerase.

**3. Rho-Independent Termination:** In some cases, the hairpin structure alone is sufficient to halt transcription. This process, known as rho-independent termination, is triggered by a sequence of uracil (U) nucleotides following the hairpin. The weak base pairing between U and A nucleotides in the DNA template further destabilizes the RNA-DNA hybrid, leading to the dissociation of RNA polymerase.

**4. Rho-Dependent Termination:** In other cases, a protein called Rho is required for termination. Rho is a helicase that binds to a specific sequence in the nascent RNA molecule. As RNA polymerase transcribes the termination signal, Rho chases after it, using ATP as energy. When Rho catches up to RNA polymerase, it disrupts the RNA-DNA hybrid, causing the release of RNA polymerase and the nascent RNA molecule.

**5. Release of the RNA Transcript:** Once RNA polymerase detaches from the DNA template, the newly synthesized RNA transcript is released. This transcript can then undergo further processing, such as capping, splicing, and polyadenylation, before it is translated into a protein.

**6. Resetting for New Transcription Cycles:** After termination, RNA polymerase dissociates from the DNA template and is ready to initiate a new round of transcription.

In summary, DNA-templated transcription termination is a complex process involving recognition of termination signals, formation of hairpin structures, the action of Rho protein (if required), and the release of the RNA transcript. This process ensures the accurate and efficient production of RNA molecules, which are essential for protein synthesis and other cellular functions.'
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Proteins (5)

Compounds (36)