Replacement by structure-dependent transposition (RST) or stem-loop replacement: A possible model for the transposition mechanism of IS<i>1272</i>.

<p>(1) Palindromic sequences (red) are present in donor and recipient sequences. (2) Palindromic sequences form a cruciform. (3a-4a) The 3’ ends of IS<i>1272</i> (stem-loop) attack and are joined to the target DNA at the 3’ feet of two stem-loops. (5a) The stem-loops on recipient sequences are removed. (6a) IS is inserted, replacing a stem-loop sequence. (3b-4b) The 3’ ends of IS attack and are joined to the target DNA at the 5’ feet of the two stem-loop. (6b) The sequence forming the stem-loop is duplicated at both ends of IS. (3c-4c) The 3’ ends of IS attack and are joined to target DNA at the 5’ of two loops. (6c) The sequence corresponding to the two loops is duplicated at both ends of IS. Red arrows, palindromic sequences; green lines, IS DNA.