title: The diversity of prokaryotic DDE transposases of the mutator superfamily, insertion specificity, and association with conjugation machineries.
abstract: Transposable elements (TEs) are major components of both prokaryotic and eukaryotic genomes and play a significant role in their evolution. In this study, we have identified new prokaryotic DDE transposase families related to the eukaryotic Mutator-like transposases. These genes were retrieved by cascade PSI-Blast using as initial query the transposase of the streptococcal integrative and conjugative element (ICE) TnGBS2. By combining secondary structure predictions and protein sequence alignments, we predicted the DDE catalytic triad and the DNA-binding domain recognizing the terminal inverted repeats. Furthermore, we systematically characterized the organization and the insertion specificity of the TEs relying on these prokaryotic Mutator-like transposases (p-MULT) for their mobility. Strikingly, two distant TE families target their integration upstream σA dependent promoters. This allowed us to identify a transposase sequence signature associated with this unique insertion specificity and to show that the dissymmetry between the two inverted repeats is responsible for the orientation of the insertion. Surprisingly, while DDE transposases are generally associated with small and simple transposons such as insertion sequences (ISs), p-MULT encoding TEs show an unprecedented diversity with several families of IS, transposons, and ICEs ranging in size from 1.1 to 52 kb.
authors.affiliation: Unité de Biologie des Bactéries pathogènes à Gram-positif, Institut Pasteur, Paris, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Guérillot
authors.forename: Patricia
authors.initials: P
authors.lastname: Siguier
authors.forename: Edith
authors.initials: E
authors.lastname: Gourbeyre
authors.forename: Michael
authors.initials: M
authors.lastname: Chandler
authors.forename: Philippe
authors.initials: P
authors.lastname: Glaser
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D019143:Evolution, Molecular; D014644:Genetic Variation; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D019895:Transposases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D019895:Transposases
keywords: evolution; genome dynamics; insertion sequence; integrative and conjugative element; transposase