Difference Between sgRNA and gRNA

sgRNA is the single guide RNA, a term used to describe gRNA, whereas gRNA is the guided RNA, an RNA molecule used to specify a particular target to the endonucleases in the CRISPR system-based genome editing. Therefore, both sgRNA and gRNA are interchangeable terms used to describe the same molecule. There is not much difference between sgRNA and gRNA.

Both sgRNA and gRNA are synthetic molecules and resemble the crRNA in the CRISPR system by function. 

Key Areas Covered

1. What is sgRNA
     – Definition, Significance
2. What is gRNA
     – Definition, Structure, Function
3. What are the Similarities Between sgRNA and gRNA
     – Outline of Common Features
4. What is the Difference Between sgRNA and gRNA
     – Comparison of Key Differences

Key Terms

Cas, CRISPR-Based Genome Editing, gRNA, sgRNA, Spacer Sequence 

What is sgRNA 

sgRNA (single guide RNA) is another term used to describe gRNA. 

Figure 1: sgRNA

What is gRNA 

gRNA (guide RNA) is a short, synthetic RNA molecule used in the CRISPR system-based genome editing, one of the highly specific types of genome modification tool. gRNA consists of a ~20 bp long nucleotide sequence that binds to a target DNA sequence of the genome. This sequence is called the spacer sequence. The gRNA molecule is composed of a scaffold sequence for the binding of Cas, the endonuclease. So, the two components of the CRISPR based genome editing are the gRNA and the CRISPR associated endonuclease (Cas). On the other hand, the genome target of the CRISPR system alters with the sequence of the gRNA. 

Figure 2: gRNA Role in Genome Editing

Three types of gRNAs are there based on the method of synthesis. They are the synthetic crRNA, lentiviral sgRNA, and synthetic sgRNA.  

Similarities Between sgRNA and gRNA 

• sgRNA and gRNA are small RNA molecules used to specify the target sequence to the endonucleases in the genome editing tools based on the CRISPR system. 
• Both have a 20 bp region that hybridizes with DNA. 
• Both are artificial molecules and do not occur in nature. 
• Both perform the same function, i.e., the function crRNA performs in the natural CRISPR system. 

Difference Between sgRNA and gRNA 

Definition 

sgRNA (single guide RNA) refers to the gRNA used in the artificial CRISPR system whereas gRNA (guide RNA) refers to the short, synthetic RNA sequences that specify the target sequence for CRISPR-based genome editing. 

• Both sgRNA and gRNA are interchangeable terms used to describe the same molecule

Conclusion 

sgRNA is another term for gRNA while gRNA is the short, synthetic RNA sequences used to specify the target sequence in the genome for the endonuclease in the CRISPR system. Both sgRNA and gRNA are one of the components of the CRISPR-based genome editing. Therefore, the main difference between sgRNA and gRNA is only the terminology. 

Reference:

1. “CRISPR Guide.” Addgene: CRISPR Guide, Available Here

Image Courtesy:

1. “15 Hegasy Cas9 DNA Tool Wiki E CCBYSA” By Guido4 – Own work (CC BY-SA 4.0) via Commons Wikimedia 
2. “CRISPR-Cas9-biologist” By J LEVIN W – Own work (CC BY-SA 4.0) via Commons Wikimedia