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Requirement of IS 911 replication before integration defines a new bacterial transposition pathway
Author(s) -
DuvalValentin G,
MartyCointin B,
Chandler M
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600395
Subject(s) - transposition (logic) , transposable element , replication (statistics) , biology , genetics , philosophy , gene , genome , linguistics , virology
Movement of transposable elements is often accompanied by replication to ensure their proliferation. Replication is associated with both major classes of transposition mechanisms: cut‐and‐paste and cointegrate formation (paste‐and‐copy). Cut‐and‐paste transposition is often activated by replication of the transposon, while in cointegrate formation replication completes integration. We describe a novel transposition mechanism used by insertion sequence IS 911 , which we call copy‐and‐paste. IS 911 transposes using a circular intermediate (circle), which then integrates into a target. We demonstrate that this is derived from a branched intermediate (figure‐eight) in which both ends are joined by a single‐strand bridge after a first‐strand transfer. In vivo labelling experiments show that the process of circle formation is replicative. The results indicate that the replication pathway not only produces circles from figure‐eight but also regenerates the transposon donor plasmid. To confirm the replicative mechanism, we have also used the Escherichia coli terminators ( terC ) which, when bound by the Tus protein, inhibit replication forks in a polarised manner. Finally, we demonstrate that the primase DnaG is essential, implicating a host‐specific replication pathway.