ISDra2 transposase TnpA

UniProtKB accession:  Q7DF83

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UniProtKB description:  A transposase that is part of insertion sequence (IS) element ISDra2, it is necessary and sufficient for both transposon excision and insertion of ISDra2. This protein alone can be provided in trans and allows transposition of an empty IS element (tnpA or tnpA-tnpB replaced by a selectable marker) (PubMed:16359337, PubMed:20090938). ISDra2 binds subterminal imperfect palindromes at the left (LE) and right (RE) ends of the element and cleaves only the 'top strand' which is circularized and subsequently reinserted into the DNA target. This is called a 'peel and paste' mechanism and increases the copy number of the IS (Probable) (PubMed:20890269). Transposition is linked to DNA replication in the absence of irradiation, with maximal activity when the 'top strand' is on the replication lagging strand, and occurs preferentially on the lagging strand (PubMed:20691900). The IS element inserts 3' of the target sequence 5'-TTGAT-3'; target duplication has not been observed (PubMed:14676423, PubMed:16359337, PubMed:20090938, PubMed:20691900).