DNA-templated transcription initiation

Definition

Target type: biologicalprocess

The initial step of transcription, consisting of the assembly of the RNA polymerase preinitiation complex (PIC) at a gene promoter, as well as the formation of the first few bonds of the RNA transcript. Transcription initiation includes abortive initiation events, which occur when the first few nucleotides are repeatedly synthesized and then released, and ends when promoter clearance takes place. [GOC:jid, GOC:txnOH, PMID:18280161]

DNA-templated transcription initiation is the process by which a DNA sequence is used as a template to create an RNA molecule. This process is essential for gene expression, as it allows the genetic information encoded in DNA to be accessed and translated into proteins. Here is a detailed description of the process:

1. **Promoter Recognition:** The process begins with the recognition of a specific DNA sequence known as a promoter by RNA polymerase. The promoter is located upstream of the gene to be transcribed and contains specific DNA sequences that act as binding sites for RNA polymerase.
2. **RNA Polymerase Binding:** Once the promoter is recognized, RNA polymerase binds to it. This binding event is facilitated by transcription factors, which are proteins that help to recruit RNA polymerase to the promoter and initiate transcription.
3. **DNA Unwinding:** After RNA polymerase binds to the promoter, it unwinds the DNA double helix, exposing the template strand. This unwinding creates a transcription bubble, which allows RNA polymerase to access the DNA template.
4. **Initiation of RNA Synthesis:** RNA polymerase uses the template strand of DNA to synthesize a complementary RNA molecule. The process begins with the synthesis of a short RNA primer, which is then extended by RNA polymerase.
5. **Elongation:** RNA polymerase continues to move along the template strand, adding nucleotides to the growing RNA chain. The nucleotides are added in a sequence that is complementary to the DNA template strand.
6. **Termination:** The process of transcription ends when RNA polymerase reaches a specific DNA sequence called a terminator. The terminator signals RNA polymerase to release the newly synthesized RNA molecule and detach from the DNA template.
7. **RNA Processing:** After transcription, the newly synthesized RNA molecule undergoes several processing steps before it can be translated into protein. These steps include capping, splicing, and polyadenylation.

The initiation of transcription is a complex process that is tightly regulated. Transcription factors play a crucial role in regulating the initiation of transcription by controlling the access of RNA polymerase to the promoter. This regulation ensures that genes are only transcribed when and where they are needed.'
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Proteins (4)

Compounds (2)