A novel transposon, Tn6009, composed of a Tn916 element linked with a Staphylococcus aureus mer operon.
OBJECTIVE
The aim of this study was to characterize a novel conjugative transposon Tn6009 composed of a Tn916 linked to a Staphylococcus aureus mer operon in representative Gram-positive and Gram-negative bacteria isolated in Nigeria and Portugal.


METHODS
Eighty-three Gram-positive and 34 Gram-negative bacteria were screened for the presence of the Tn6009 using DNA-DNA hybridization, PCR, hybridization of PCR products, sequencing and mating experiments by established procedures.


RESULTS
Forty-three oral and 23 urine Gram-negative and Gram-positive isolates carried the Tn6009. Sequencing was performed to verify the direct linkage between the mer resistance genes and the tet(M) gene. A Nigerian Klebsiella pneumoniae, isolated from a urinary tract infection patient, and one commensal isolate from each of the other Tn6009-positive genera, Serratia liquefaciens, Pseudomonas sp., Enterococcus sp. and Streptococcus sp. isolated from the oral and urine samples of healthy Portuguese children, were able to act as donors and conjugally transfer the Tn6009 to the Enterococcus faecalis JH2-2 recipient, resulting in tetracycline- and mercury-resistant E. faecalis transconjugants.


CONCLUSIONS
This study reports a novel non-composite conjugative transposon Tn6009 containing a Tn916 element linked to an S. aureus mer operon carrying genes coding for inorganic mercury resistance (merA), an organic mercury resistance (merB), a regulatory protein (merR) and a mercury transporter (merT). This transposon was identified in 66 isolates from two Gram-positive and three Gram-negative genera and is the first transposon in the Tn916 family to carry the Gram-positive mer genes directly linked to the tet(M) gene.
Soge
Olusegun O
OO
Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA.
Beck
Nicola K
NK
White
Teresa M
TM
No
David B
DB
Roberts
Marilyn C
MC
D001426:Bacterial Proteins / Q000235:genetics; D002648:Child; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D024881:Drug Resistance, Bacterial; D023061:Gene Order; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D008190:Lyases / Q000235:genetics; D008628:Mercury / Q000633:toxicity; D008969:Molecular Sequence Data; D009055:Mouth / Q000382:microbiology; D009549:Nigeria; D009693:Nucleic Acid Hybridization; D010088:Oxidoreductases / Q000235:genetics; D016133:Polymerase Chain Reaction; D011174:Portugal; D017422:Sequence Analysis, DNA; D013753:Tetracycline Resistance; D014556:Urine / Q000382:microbiology
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C051124:MerR protein, Bacteria; C083138:Tet M resistance protein, Bacteria; D010088:Oxidoreductases; C021551:mercuric reductase; D008190:Lyases; C097247:MerB protein, Bacteria; D008628:Mercury