National Center for
2XQC: Deinococcus Radiodurans Isdra2 Transposase Complexed With Left End Recognition And Cleavage Site And Zn
DNA recognition and the precleavage state during single-stranded DNA transposition in D. radiodurans
EMBO J. (2010) 29 p.3840-3852
Bacterial insertion sequences (ISs) from the IS200/IS605 family encode the smallest known DNA transposases and mobilize through single-stranded DNA transposition. Transposition by one particular family member, ISDra2 from Deinococcus radiodurans, is dramatically stimulated upon massive gamma irradiation. We have determined the crystal structures of four ISDra2 transposase/IS end complexes; combined with in vivo activity assays and fluorescence anisotropy binding measurements, these have revealed the molecular basis of strand discrimination and transposase action. The structures also show that previously established structural rules of target site recognition that allow different specific sequences to be targeted are only partially conserved among family members. Furthermore, we have captured a fully assembled active site including the scissile phosphate bound by a divalent metal ion cofactor (Cd(2)(+)) that supports DNA cleavage. Finally, the observed active site rearrangements when the transposase binds a metal ion in which it is inactive provide a clear rationale for metal ion specificity.