Unveiling the Role of RNA Polymerase in Gene Expression

Overview

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• Source: Microbioz India


• Date: 02 Dec,2023

In molecular biology, RNA Polymerase, also known as RNA Pol or RNAP, is an enzyme that synthesizes RNA from a DNA template. With the aid of the enzyme helicase, which breaks apart damaged DNA strands, RNA polymerase copies the DNA sequence into an RNA sequence during the transcription process.

Surely! It is imperative that we look closely at how RNA polymerase acts in gene expression.

Initiation:

1. The promoter region of the gene on the DNA template is recognized and binds to RNA polymerase.
2. Promoters often have specific sequences that indicate the start of transcription.
3. This closed complex is formed by this binding.

Promoter Clearance:

1. Closed complex undergoes conformational changes leading to an open complex being formed.
2. The open complex allows for RNA polymerase to access the DNA template to transcribe.

Elongation:

1. Producing an RNA strand, RNA polymerase translocates along the DNA template in a 5’ à 3’ direction.
2. Unwinding DNA ahead and rewinding DNA behind it to keep it open as it progresses.

Termination:

1. A termination signal is reached which results in dissociation of RNA polymerase from DNA template.
2. Termination signals can be particular sequences or structural elements on the RNA transcript.

RNA Processing:

1. In eukaryotes, posttranscriptional modifications occur to primary RNA transcript (premRNA).
2. These include capping at 5’ end, addition of a polyA tail at the 3’ and removal of introns.
3. These modifications increase stability, facilitate transport and direct translation.

Function of RNA Transcript:

1. Depending on its type, matured RNA transcript has various functions.
2. They carry the relevant genetic codes from nucleus to cytoplasm for translation purpose mRNA
3. rRNA acts as a building block for ribosomes
4. tRNA brings amino acids to ribosome during protein synthesis

Regulation:

1. Transcription factors, activators and repressors regulate binding between promotion and RNAP
2. Epigenetic modification like methylation of DNA and acetylation of histones also affects transcription.

Untangling the intricacies of RNA polymerase mediated transcription is key to understanding gene expression complexity and how it is regulated in cellular processes.