The DEDD Transposases

A similar type of Tpase, known as a DEDD Tpase, is related to the Holiday junction resolvase, RuvC (Choi, et al., 2003, Buchner, et al., 2005) but is at present limited to only a single known IS family (IS110). The organization of family members is quite different from that of the DDE ISs: they do not contain the typical terminal IRs of the DDE IS (although one subgroup, IS1111, carry sub-terminal IR) and do not generate flanking target DRs on insertion. This implies that their transposition occurs using a different mechanism to the DDE IS. It seems probable that an intermediate resembling a four-way Holliday junction is involved.

Moreover, in contrast to the DDE transposases in which a DNA binding domain invariably precedes the catalytic domain, DEDD transposases appear to include a DNA binding domain downstream from the catalytic domain.

References :

• Buchner JM, Robertson AE, Poynter DJ, Denniston SS & Karls AC (2005) Piv Site-Specific Invertase Requires a DEDD Motif Analogous to the Catalytic Center of the RuvC Holliday Junction Resolvases 10.1128/JB.187.10.3431-3437.2005. J. Bacteriol. 187: 3431-3437.
• Choi S, Ohta S & Ohtsubo E (2003) A novel IS element, IS621, of the IS110/IS492 family transposes to a specific site in repetitive extragenic palindromic sequences in Escherichia coli. J Bacteriol 185: 4891-4900.