The bacterial Tn9 chloramphenicol resistance gene: an attractive DNA segment for Mos1 mariner insertions.
The eukaryotic mariner transposons are currently thought to have no sequence specificity for integration other than to insert within a TA contained in a degenerated [TA](1-4) tract, either in vitro or in vivo. We have investigated the properties of a suspected hotspot for the integration of the mariner Mos1 element, namely the Tn9 cat gene that encodes a chloramphenicol acetyl transferase. Using in vitro and bacterial transposition assays, we confirmed that the cat gene is a preferential target for MOS1 integration, whatever its sequence environment, copy number or chromosomal locus. We also observed that its presence increases transposition rates both in vitro and in bacterial assays. The structural and sequence features that constitute the attractiveness of cat were also investigated. We first demonstrated that supercoiling is essential for the cat gene to be a hot spot. In contrast to the situation for Tc1-like elements, DNA curvature and bendability were not found to affect integration target preferences. We found that Mos1 integrations do not occur randomly along the cat gene. All TA dinucleotides that are preferred for integration were found within either TATA or TA x TA motifs. However, these motifs are not sufficient to constitute an attractive dinucleotide, since four TATA and TA x TA sites are cold spots.
Crénès
Gwénaëlle
G
GICC, UMR CNRS 6239, Université François Rabelais de Tours, UFR des Sciences et Techniques, Parc de Grandmont, 37200, Tours, France.
Ivo
Dina
D
Hérisson
Joan
J
Dion
Sarah
S
Renault
Sylvaine
S
Bigot
Yves
Y
Petit
Agnès
A
D001483:Base Sequence; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D002702:Chloramphenicol Resistance / Q000235:genetics*; D017124:Conserved Sequence; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D018900:Dinucleotide Repeats; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D048168:Escherichia coli K12 / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D008957:Models, Genetic; D008969:Molecular Sequence Data; D019895:Transposases / Q000235:genetics*
D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C111652:mariner transposases; D015500:Chloramphenicol O-Acetyltransferase; D019895:Transposases