What is the Difference Between crRNA tracrRNA and gRNA?
🆚 Go to Comparative Table 🆚The CRISPR-Cas9 system is an immune mechanism in bacteria and archaea that has been adapted as a gene-editing tool in biotechnology. It consists of two main components: CRISPR RNA (crRNA) and transactivating CRISPR RNA (tracrRNA), which are collectively known as guide RNA (gRNA). The differences between crRNA, tracrRNA, and gRNA are as follows:
- crRNA (CRISPR RNA): This is a 17-20 nucleotide sequence that is complementary to the target DNA. It is part of the gRNA and plays a crucial role in recognizing the target DNA sequence.
- tracRNA (transactivating CRISPR RNA): This is the second part of the gRNA and serves as a binding scaffold for the Cas nuclease. It helps in guiding the Cas9 enzyme to the target DNA.
- gRNA (guide RNA): This is the combination of crRNA and tracrRNA. It is one of the two main components of the CRISPR-Cas9 system and is responsible for recognizing target DNA sequences and guiding nucleases to make double-strand breaks in the foreign genetic material.
In summary, crRNA is the part of gRNA that is complementary to the target DNA, while tracrRNA serves as a binding scaffold for the Cas nuclease. gRNA is the combination of both crRNA and tracrRNA, playing a crucial role in recognizing target DNA and guiding nucleases to make double-strand breaks.
Comparative Table: crRNA tracrRNA vs gRNA
Here is a table summarizing the differences between crRNA, tracrRNA, and gRNA:
| Feature | crRNA (Clustered Regularly Interspaced Short Palindromic Repeats RNA) | tracrRNA (Trans-activating crRNA) | gRNA (Guide RNA) |
|---|---|---|---|
| Function | One of the two types of RNA that is complementary to the target DNA sequence. | The second type of RNA of the CRISPR system, serving as a binding scaffold for the Cas nuclease. | Composed of crRNA and tracrRNA, involved in recognizing bacteriophage DNA and guiding endonucleases towards the target. |
| Composition | Part of the two-part guide RNA complex in the CRISPR-Cas9 system. | Part of the two-part guide RNA complex in the CRISPR-Cas9 system. | Comprises 100 base pairs and is generated from crRNA and tracrRNA when cloned plasmids are introduced into cells. |
| Structure | Contains a spacer sequence. | Contains a constant region and a spacer sequence. | Hybridizes with tracrRNA through a 16-nt complementary sequence. |
| Role in CRISPR-Cas9 | Helps recognize target DNA sequences and guide Cas9 nuclease to make double-strand breaks. | Participates in the maturation process of crRNA by creating a duplexed version based on a nucleic acid sequence in a CRISPR array. | Directs Cas9 proteins to make double-strand breaks in target DNA. |
crRNA, tracrRNA, and gRNA are RNA sequences found in bacteria and archaea, and they all belong to the CRISPR system. They are involved in recognizing bacteriophage DNA and guiding endonucleases towards the target, hence directing the Cas9 nuclease to make double-strand breaks in the target DNA.