Conjugating plasmids are preferred targets for Tn7.
Most transposons display target site selectivity, inserting preferentially into sites that contain particular features. The bacterial transposon Tn7 possesses the unusual ability to recognize two different classes of target sites. Tn7 inserts into these classes of target sites through two transposition pathways mediated by different combinations of the five Tn7-encoded transposition proteins. In one transposition pathway, Tn7 inserts into a unique site in the bacterial chromosome, attTn7, through specific recognition of sequences in attTn7; the other transposition pathway ignores the attTn7 target. Here we examine targets of the non-attTn7 pathway and find that Tn7 preferentially inserts into bacterial plasmids that can conjugate between cells. Furthermore, Tn7 appears to recognize preferred targets through the conjugation process, as we show that Tn7 inserts poorly into plasmids containing mutations that block plasmid transfer. We propose that Tn7 recognizes preferred targets through features of the conjugation process, a distinctive target specificity that offers Tn7 the ability to spread efficiently through bacterial populations.
Wolkow
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CA
Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
DeBoy
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Craig
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NL
D001426:Bacterial Proteins / Q000235:genetics; D001435:Bacteriophages / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D003227:Conjugation, Genetic / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics*; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C063238:traY protein, E coli