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Atypical association of DDE transposition with conjugation specifies a new family of mobile elements
Author(s) -
Brochet Mathieu,
Da Cunha Violette,
Couvé Elisabeth,
Rusniok Christophe,
TrieuCuot Patrick,
Glaser Philippe
Publication year - 2009
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06579.x
Subject(s) - transposase , transposable element , biology , transposition (logic) , integrases , genetics , bacterial conjugation , insertion sequence , integrase , mobile genetic elements , plasmid , genome , gene , linguistics , philosophy
Summary We describe in Streptococcus agalactiae an atypical family of conjugative transposons named Tn GBSs which associates DDE transposition and conjugation. We present evidence that the transposition of Tn GBS2 , the prototype of this family, is catalysed by a new class of DDE transposases that are widespread in Gram‐positive bacteria. Remarkably, transposition occurs in intergenic regions, 15 or 16 bp upstream the −35 sequence of promoters, minimizing the burden on the host cell and suggesting an association between transcription and transposition. Transposition catalyses the formation of a circular intermediate that is substrate for subsequent conjugative intercellular transfer. Conjugation is initiated at an origin of transfer by a transposon‐encoded relaxase. Whereas all integrative and conjugative elements described so far encode a phage‐related integrase, Tn GBS2 is the first example of conjugative transposon whose recombination is mediated by a DDE transposase. The combination of DDE transposition with conjugation implies recombination constraints linked to the physical separation of donor and recipient molecules.