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). Mg(2+), Mn(2+) and Cd(2+) support DNA cleavage whereas Ca(2+) and Zn(2+) do not. Both the excision and insertion steps are inhibited by TnpB. Homodimer. Transposition of this element is induced approximately 100-fold by 10 kGy gamma irradiation and approximately 50-fold by 600 J/m(2) of UV irradiation, both of which damage DNA. It rarely transposes without irradiation (PubMed:16359337). Both excision and insertion of ISDra2 are increased by irradiation, transposition occurs in irradiated cells, probably triggered by single-stranded DNA formed during genome reassembly, and is not due to specific induction of TnpA expression (PubMed:20090938). The helix containing the catalytic Tyr-132 (residues 127-133) is highly mobile. Recognition of the 5-base sequence immediately preceding the cleavage site is mediated by base-pairing to an imperfect palindrome, by sandwiching the fifth nucleotide between Tyr-30 and Trp-107 and hydrogen bonding to His-32, and by main chain atoms of Leu-106 and Trp-107. When tested in an R1 strain with only a single IS200 element (DR_1651 and DR_1652), required for transposition of the IS element; single tnpA or double tnpA-tnpB deletions leads to loss of transposition. Belongs to the IS200/IS605 insertion sequence (IS) element family, formerly called IS8301 (PubMed:14676423, PubMed:20090938). This element is subject to strain polymorphism; in the ATCC 13939 / R1 strain genome sequenced by White there are 7 complete and 1 incomplete IS200/IS605 elements (PubMed:10567266). Another R1 strain has only 1 copy of this element (PubMed:14676423, PubMed:20090938). Another group found 2 copies of this element in untreated R1 strains (PubMed:16359337, PubMed:10567266, PubMed:14676423, PubMed:20090938). Belongs to the transposase 17 family.