Introduction
The phrase termination corresponds to the condition, activity, or process of coming to conclusions. The phrase is often used in biology to describe any biological process that terminates or completes a biological structure.
The primary difference between Rho-Dependent and Rho-Independent termination is that, in Rho-Dependent termination, the Rho factor binds to the transcript and ends transcription by breaking hydrogen bonds between the transcript and template, whereas, in Rho-Independent termination, the hairpin loop structure and consequent U-rich portion in the transcript are formed to cause the termination.
The three steps of transcription involve initiation, elongation, and termination. The RNA polymerase enzyme binds to the gene’s promoter sequence and begins catalysing the synthesis of the RNA strand. RNA polymerase constructs the RNA strand by adding nucleotides until the terminator sequence is discovered. Rho-Independent and Rho-Dependent termination are the two main mechanisms in prokaryotes. The protein Rho factor exhibits helicase activity.
Table of Contents
- Rho-Dependent Termination
- Rho-Independent Termination
- Difference between Rho-Dependent and Rho-Independent Termination
- Frequently Asked Questions (FAQs)
Rho-Dependent Termination
One of the two transcription termination mechanisms prokaryotes use is Rho-dependent termination. The protein Rho factor exhibits helicase activity.
The Rho protein binds to the RNA transcript and moves in a 5′-3′ direction with the RNA polymerase, which promotes the breaking of hydrogen bonds between the DNA template and RNA transcript. Rho factor separates the DNA/RNA hybrid as it approaches the transcription bubble, releasing the transcript from the bubble. When this takes place, it terminates the transcription process.
Although most Rho-dependent terminators have been found in enteric bacteria, they have also been found in Gram-positive microorganisms, indicating that they may be widespread among microbes.
Rho-Independent Termination
An mRNA sequence is created as RNA polymerase advances. Prokaryotic transcription is terminated using a second method called Rho-independent termination. A terminator region usually has an inverted repetitive pattern. An Adenine-rich region (AAAA) follows the inverted repeat sequence immediately.
Because the two areas in the inverted repeat sequence region complement one another, hydrogen bonding enables it to generate a hairpin loop structure. The hairpin structure stops the RNA polymerase activity. The U-rich region will follow next.
Moreover, weak interactions exist between the U bases of the transcript and the A bases of the template in the U-rich regions. The weak Adenine-Uracil interactions separate the RNA transcript and DNA template, destabilising them. Eventually, the transcript breaks out from the transcription location.
Difference between Rho-Dependent and Rho-Independent Termination
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Rho-Dependent Termination |
Rho-Independent Termination |
|---|---|
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Rho-dependent termination takes place when Rho binds to ribosome-free mRNA |
Prokaryotes use intrinsic termination, also known as rho-independent termination, to indicate the termination of transcription and release the newly created RNA molecule. |
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Formation of hairpin loop structure does not take place |
Formation of hairpin loop structure takes place |
|
Rho factor utilises ATP |
Rho factor does not utilise ATP |
|
Uracil rich region in the transcript is absent |
Uracil rich region in the transcript is present |
In Rho-dependent termination, a Rho protein is responsible for transcriptional termination. The formation of the hairpin loop structure, on the other hand, results in Rho-independent termination. Therefore, this is the main difference between Rho-dependent and Rho-Independent termination.
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