In molecular biology, insertional mutagenesis is the creation of mutations in DNA by the addition of one or more base pairs.
Such insertional mutations can occur naturally, mediated by viruses or transposons, or can be artificially created for research purposes in the lab.
A transposon such as the P element of Drosophila melanogaster is allowed to integrate at random locations in the genome of the organism being studied.
Likewise, if the viral DNA is inserted into a repressor, the promoter's corresponding gene may be over-expressed – leading to an overabundance of its product and altered cellular activity.
Insertional mutagenesis is possible whether the virus is of the self-inactivating types commonly used in gene therapy or competent to replicate.
[2] Insertional inactivation is a technique used in recombinant DNA engineering where a plasmid (such as pBR322)[3] is used to disable the expression of a gene.
An alternative strategy for insertional mutagenesis has been used in vertebrate animals to find genes that cause cancer.
In this case a transposon, e.g. Sleeping Beauty, is designed to interrupt a gene in such a way that it causes maximal genetic havoc.