BINDING OF THE PROTEIN FROM THERMUS-AQUATICUS ISLTAQ1 TO ITS INVERTEDREPEAT IN-VITRO

We have isolated from Thermus aquaticus an insertion-sequence-like gen etic element (ISLtaq1) that induces thermotolerance and has a high seq uence similarity to IS150 belonging to the IS3 family. An open reading frame on ISLtaq1, termed ORF1, encodes the ORFI protein, which carrie s a DNA-binding motif. In this study, we found an imperfect inverted r epeat in ISLtaq1. We next overproduced and purified a His-tagged ORF1 protein. Gel retardation analysis demonstrated that this protein speci fically bound to an DNA fragment containing the inverted repeat in ISL taq1. These results suggest that ISLtaq1 and the ORFI protein are an i nsertion sequence and part of the transposase encoded by ISLtaq1, resp ectively.