Related Experiment Video
Updated: May 11, 2026
11:52
Analysis of LINE-1 Retrotransposition at the Single Nucleus Level
Published on: April 23, 2016
A highly active synthetic mammalian retrotransposon
1Department of Molecular Biology and Genetics and High Throughput Biology Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Nature
|May 21, 2004
Summary
Synthetic biology approaches enhanced LINE-1 (long interspersed nuclear element-1) retrotransposon activity. Modifying L1 sequences boosted RNA and protein levels, significantly increasing transposition for potential genome engineering tools.
Area of Science:
- Genomics
- Molecular Biology
- Synthetic Biology
Background:
- LINE-1 (L1) elements are abundant retrotransposons in mammalian genomes.
- L1 transcription is hampered by an elongation defect, limiting L1 RNA and protein expression.
- This defect is a key regulator of L1 transposition frequency.
Purpose of the Study:
- To investigate methods for overcoming the L1 transcriptional elongation defect.
- To enhance L1 retrotransposition efficiency through synthetic sequence modification.
- To assess the potential of engineered L1 elements as genomic tools.
Main Methods:
- Synthesized L1 open reading frames from synthetic oligonucleotides, altering 24% of the sequence without changing amino acids.
- Replaced wild-type L1 sequences with synthetic versions in a retrotransposition assay.
- Quantified L1 RNA, protein levels, and transposition activity.
Main Results:
- Synthetic L1 resynthesis significantly increased steady-state L1 RNA and protein levels.
- Retrotransposition activity of synthetic L1 elements increased over 200-fold compared to wild-type.
- Demonstrated that large, conserved cis-acting sequences within L1 coding regions are not essential for retrotransposition.
Conclusions:
- Bypassing the L1 transcriptional defect via synthetic sequence optimization dramatically enhances retrotransposition.
- Highly active synthetic L1 elements were generated, exceeding previously known activity levels.
- These engineered L1 elements show promise as novel tools for mammalian genome manipulation.
More Related Videos
10:13An Efficient In Vitro Transposition Method by a Transcriptionally Regulated Sleeping Beauty System Packaged into an Integration Defective Lentiviral Vector
Published on: January 12, 2018
11:04RNA Next-Generation Sequencing and a Bioinformatics Pipeline to Identify Expressed LINE-1s at the Locus-Specific Level
Published on: May 19, 2019
Related Concept Videos
02:13Overview of Transposition and Recombination
Transposons make up a significant part of genomes of various organisms. Therefore, it is believed that transposition played a major evolutionary role in speciation by changing genome sizes and modifying gene expression patterns. For example, in bacteria, transposition can lead to conferring antibiotic resistance. Movement of transposable elements within the genetic pool of pathogenic bacteria can aid in transfer of antibiotic-resistant genetic elements. In eukaryotes, transposons can carry out...
02:57DNA-only Transposons
DNA-only transposons are called autonomous transposons since they code for the enzyme transposase that is required for the transposition mechanism. Insertion of transposons can alter gene functions in multiple ways. They can mutate the gene, alter gene expression by introducing a novel promoter or insulator sequence, introduce new splice sites, and change the mRNA transcripts produced, or remodel chromatin structure.
The donor site from where the transposon is excised is either degraded or...
The donor site from where the transposon is excised is either degraded or...
02:33Retroviruses
Retroviruses and retrotransposons both insert copies of their genetic elements into the genome of the host cell. Thus, the viral genes are passed on when the host genome is replicated or translated. A typical retroviral DNA sequence contains 3-4 genes that encode the different proteins required for its structural assembly and function as a molecular parasite. This DNA is transcribed into a single mRNA, which is very similar in structure to conventional mRNAs, i.e., it is capped at the 5’...
03:08LTR Retrotransposons
LTR retrotransposons are class I transposable elements with long terminal repeats flanking an internal coding region. These elements are less abundant in mammals compared to other class I transposable elements. About 8 percent of human genomic DNA comprises LTR retrotransposons. Some of the common examples of LTR retrotransposons are Ty elements in yeast and Copia elements in Drosophila.
The internal coding region of LTR retrotransposons and their mechanism of transposition closely resembles a...
The internal coding region of LTR retrotransposons and their mechanism of transposition closely resembles a...
03:18Non-LTR Retrotransposons
As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...
01:24Transposons
Transposons, or "jumping genes," are small mobile genetic elements (MGEs) that range from 700 to 40,000 base pairs in length. They are found in all organisms and can move within the same chromosome or transfer to different chromosomes. In some cases, transposons can also jump between different host DNA molecules, such as plasmids or viruses, contributing to genetic variability.Barbara McClintock first discovered these mobile genetic elements in the 1940s while studying maize genetics, and she...