Transposase

Transposase is an enzyme that catalyzes the movement of transposable elements within genomes. It is encoded by DNA transposons in bacteria and eukaryotes and plays a central role in transposition, the process by which a DNA element changes its genomic position. Transposases are diverse but share a common function of cutting and joining DNA.

Most DNA transposons are flanked by terminal inverted repeats. Transposase binds these ends, excises the element from its original location, and joins it into a new site in the genome. The insertion often creates short target site duplications. Many transposases belong to the DDE superfamily, using two metal ions coordinated by catalytic residues (often Asp, Asp, and Glu) to perform DNA cleavage and strand transfer.

Transposition can generate mutations, alter gene expression, and contribute to genome rearrangements, providing raw material for evolution. In cells, transposition is carefully regulated by host factors, DNA methylation, chromatin structure, and small RNA pathways to limit genome instability.

Several transposase systems are widely used in genetic engineering, including Sleeping Beauty and piggyBac, which enable efficient cut-and-paste transposition in mammalian cells. Other families include Tc1/mariner and hAT. Although transposases are related to viral integrases, they generally operate on DNA transposons rather than retrotransposons, which move via an RNA intermediate.