What is the Difference Between DNA Transposons and Retrotransposons

The key difference between DNA transposons and retrotransposons is that DNA transposons are mobile genetic elements that move from one place to another in the genome by using a cut and paste mechanism, while retrotransposons are mobile genetic elements that move from one place to another in the genome by using copy and paste mechanism.

Mobile genetic elements (MGEs) are segments of DNA that encode specific enzymes and proteins that mediate their movement within the genome, or that can be transferred from one species to another. They are also known as selfish genetic elements. Transposable elements represent one of the several types of mobile genetic elements. There are two main types of transposable elements: DNA transposons and retrotransposons. Therefore, DNA transposons and retrotransposons are mobile genetic elements that can move from place to place in the genome.

CONTENTS

1. Overview and Key Difference
2. What are DNA Transposons 
3. What are Retrotransposons
4. Similarities – DNA Transposons and Retrotransposons
5. DNA Transposons vs Retrotransposons in Tabular Form
6. Summary – DNA Transposons vs Retrotransposons

What are DNA Transposons?

DNA transposons are mobile genetic elements that move from one place to another in the genome by using a cut and paste mechanism. They belong to class II transposable elements that move through a DNA intermediate. This is opposed to class I transposable elements (retrotransposons) that move through an RNA intermediate. Normally, DNA transposons move around in the genome by using a cut and paste method. This method requires a transposase enzyme that catalyzes the movement of the DNA from its current location in the genome and insertion in the new location.

This transposition requires three DNA sites on the transposon (two at each end of the transposon called terminal inverted repeats and one at the target site). The transposase enzyme will bind to the terminal inverted repeats of the transposon and mediates synapsis of the transposon ends. Then transposase enzyme disconnects the element from the flanking DNA of the original donor site and mediates the joining of the transposon to the new insertion site in the genome. The addition of transposon to the new location causes short gaps on either side of the inserted segment. Host systems repair these gaps, resulting in the target sequence duplication (TSD), which is characteristic of transposition.

What are Retrotransposons?

Retrotransposons are mobile genetic elements that move from one place to another in the genome by using a copy and paste mechanism. They belong to class I transposable elements. Class I transposable elements (retrotransposons) move through an RNA intermediate in the genome. They are a type of genetic component that copy and paste themselves into different genomic locations.

First, they are transcribed from DNA to RNA. Then the RNA produced is reverse transcribed to DNA. This copied DNA is later inserted back into the genome at a new location. The reverse transcription is catalyzed by reverse transcriptase. Reverse transcriptase is often encoded by retrotransposon itself. The integration is carried out by an enzyme called integrase. Furthermore, are commonly three types: long terminal repeats (LTR), long interspersed nuclear elements (LINE), and short interspersed nuclear elements (SINE).

What are the Similarities Between DNA Transposons and Retrotransposons?

• DNA transposons and retrotransposons are mobile genetic elements.
• Both are classified under transposable elements.
• Both are known as jumping genes.
• They can move from place to place in the genome.
• They are evolutionary very important.

What is the Difference Between DNA Transposons and Retrotransposons?

DNA transposons are mobile genetic elements that move from one place to another in the genome by using a cut and paste mechanism, while retrotransposons are mobile genetic elements that move from one place to another in the genome by using a copy and paste mechanism. Thus, this is the key difference between DNA transposons and retrotransposons. Furthermore, DNA transposons belong to class II transposable elements, while retrotransposons belong to class I transposable elements.

The below infographic presents the differences between DNA transposons and retrotransposons in tabular form for side by side comparison.

Summary – DNA Transposons vs Retrotransposons

DNA transposons and retrotransposons are mobile genetic elements. DNA transposons move from one place to another in the genome by using a cut paste mechanism. Retrotransposons move from one place to another in the genome by using a copy and paste mechanism. So, this summarizes the difference between DNA transposons and retrotransposons.

Reference:

1. Muñoz-López, Martín, and José L García-Pérez. “DNA Transposons: Nature and Applications in Genomics.” Current Genomics, Bentham Science Publishers Ltd., Apr. 2010.
2. “Retroposon.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “DNA Transposon” By Mariuswalter – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Retrotransposons” By Mariuswalter – Own work (CC BY-SA 4.0) via Commons Wikimedia