Characterization of the specific DNA-binding properties of Tnp26, the transposase of insertion sequence IS26

Abstract

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The RuvABC Holliday Junction Processing System Is Not Required for IS 26 -Mediated Targeted Conservative Cointegrate Formation

“…We recently reported the construction of a series of IS 26 derivatives in which alterations to the DNA sequence near the left end of the IS had been introduced in order to alter specific amino acid residues in either the N-terminal F4F motif or the HTH domain ( 14 ). The positions of these mutations are shown in Fig.…”

“…2B . The mutations generally reduced the efficiency of the copy-in reaction to levels below the limit of detection ( 14 ). For the targeted conservative reaction, when both participating ISs included the mutation, the efficiency was also substantially reduced (at least 2 orders of magnitude) ( 14 ).…”

“…The mutations generally reduced the efficiency of the copy-in reaction to levels below the limit of detection ( 14 ). For the targeted conservative reaction, when both participating ISs included the mutation, the efficiency was also substantially reduced (at least 2 orders of magnitude) ( 14 ). Here, the impact of these nucleotide substitutions (generally two adjacent base pairs) and consequent single amino acid alterations on crosses between each mutant IS 26 and the wild type-IS 26 were investigated.…”

“…A comparison of the transposases encoded by the IS in the IS 26 family has provided some insight ( 13 ), as it revealed an unusual conserved motif in a short segment at the N terminus in addition to a trihelical helix-turn-helix (HTH) domain, which is the DNA binding domain ( 14 ), and the catalytic domain. The N-terminal segment includes two planar aromatic residues, usually F (phenylalanine) but occasionally Y (tyrosine), separated by 4 amino acids (aa).…”

“…The F4F motif has not been detected in ISs from any other IS family and is likely key to the unusual capabilities of IS 26 family members. More recent in vivo and in vitro studies have demonstrated a role for both of the N-terminal features of Tnp26, namely, F4F and HTH, in activity and in binding of Tnp26 to the IS 26 TIR ( 14 ).…”