Name: Bacterial RNA Polymerase and Sigma Factor
Uploaded: 2020-11-23T11:47:36
Description: Learn by watching this video about Bacterial RNA Polymerase and Sigma Factor at JoVE.com

A gene in DNA form must first be converted into a messenger RNA in a process called transcription. This mRNA is then translated by a ribosome to produce proteins. The protein which transcribes DNA into RNA is called an RNA Polymerase.
The bacterial RNA Polymerase core enzyme consists of five polypeptide subunits: two identical alpha subunits, beta and beta-prime subunits, and an omega subunit.
A transcription factor, called sigma, associates with the core enzyme to produce the RNA polymerase holoenzyme.

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	<li>Werner, Finn, and Dina Grohmann. &#34;Evolution of multisubunit RNA polymerases in the three domains of life.&#34; Nature Reviews Microbiology 9, no. 2 (2011): 85.</li>
	<li>Burton, Zachary F. Evolution Since Coding: Cradles, Halos, Barrels, and Wings. Academic Press, 2017.</li>
	<li>Tomar, Sushil Kumar, and Irina Artsimovitch. &#34;NusG-Spt5 Proteins Universal Tools for Transcription Modification and Communication.&#34; Chemical reviews 113, no. 11 (2013): 8604-8619.</li>
</ol>

bacterial rna polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize DNA sequences specifically. To help the RNAP recognize DNA sequences with high affinity, specialized proteins called transcription factors bind to particular regions of DNA to initiate transcription. In bacteria, the sigma factor helps the RNAP recognize the promoter sequence and secures its binding at the transcription start site. Bacteria contain a variety of sigma factors that associate with different promoter sequences. Such different sigma factors bind to the cellular pool of RNAPs to express different genes, depending on the cellular requirement.
Other prokaryotic transcription factors allow the cell to turn transcription of certain genes on or off in response to changes in environmental or cellular conditions. Depending on the number of genes targeted, these transcription factors can control gene expression locally or globally. Some transcription factors use their signal-sensing domains to sense the change and modulate the transcription rate by controlling RNAP binding on the template DNA. Thus, even with a single RNAP enzyme, bacteria can use different transcription factors to control which gene to express and when.

Learn by watching this video about Bacterial RNA Polymerase and Sigma Factor at JoVE.com

Bacterial RNA Polymerase and Sigma Factor

Bacterial RNA Polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. ...