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.
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
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.