transposoners

Transposons, also referred to as transposoners in some sources, are DNA sequences that can move from one genomic location to another. They are found in nearly all organisms and can contribute to genome size, structure, and regulation, as well as generate genetic variation.

They are classified into two main classes. Class I retrotransposons move via an RNA intermediate: transcription produces RNA, which is reverse-transcribed into DNA and inserted elsewhere in the genome. This class includes long terminal repeat (LTR) retrotransposons and non-LTR elements such as LINEs and SINEs. Class II DNA transposons move directly as DNA, typically using a transposase enzyme to excise and reinsert the element; some transpose via a replicative, copy-and-paste mechanism.

In bacteria and archaea, transposable elements include insertion sequences and composite transposons; in eukaryotes they contribute to gene diversification, regulatory variation, and chromosomal rearrangements. Transposons can disrupt genes, alter expression, or provide novel regulatory sequences, affecting fitness and evolution.

Host genomes regulate transposition through epigenetic silencing (DNA methylation, histone modifications) and small RNA pathways such as piRNAs. Deregulation can be associated with mutagenesis, cancer, and aging in some contexts.

Transposons are also valuable tools in research and biotechnology. Engineered transposons enable insertional mutagenesis and tagging in model organisms, while systems like Sleeping Beauty and piggyBac are used for stable gene delivery in vertebrates.