Streptococcus pneumoniae transposon Tn1545/Tn6003 changes to Tn6002 due to spontaneous excision in circular form of the erm(B)- and aphA3-containing macrolide-aminoglycoside-streptothricin (MAS) element.
The macrolide-aminoglycoside-streptothricin (MAS) element, an ∼4.2-kb insertion containing erm(B) and aphA3 resistance determinants, distinguishes Streptococcus pneumoniae transposon Tn1545/Tn6003 from Tn6002. Here, it is shown to be an unstable genetic element that, although it lacks recombinase genes, can exploit long, erm(B)-containing direct repeats acting as att sites for spontaneous excision that may result in loss. Consequent to excision, which is RecA independent, Tn1545/Tn6003 changes to Tn6002. In pneumococcal populations harboring Tn1545/Tn6003, the latter appears to coexist with Tn6002.
Unit of Microbiology, Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, Ancona, Italy.
Claudio
C
Palmieri
Marina
M
Mingoia
Orietta
O
Massidda
Eleonora
E
Giovanetti
Pietro E
PE
Varaldo
D004251:DNA Transposable Elements; D004270:DNA, Circular; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016680:Genome, Bacterial; D042822:Genomic Instability; D006801:Humans; D016254:Mutagenesis, Insertional; D013296:Streptococcus pneumoniae / Q000235:genetics*
D004251:DNA Transposable Elements; D004270:DNA, Circular