Excision and transposition of Tn5 upon insertion in the hha gene of Escherichia coli.
We report the occurrence of Tn5 secondary transpositions in Escherichia coli HB101 hha::Tn5(pANN202-312). Tn5-induced hha mutants (hemolysin overproducers) segregated at high frequency either hemolysin-negative clones or clones showing the parental hemolytic phenotype (reduced hemolysin production). Secondary transpositions of Tn5 appeared to be responsible for the phenotypes of both types of derivatives. The hemolysin-negative clones no longer harboured Tn5 in the hha gene, but rather Tn5 was in the hly genes of the hemolytic plasmid pANN202-312. The derivatives that recovered the parental hemolytic phenotype contained a single copy of Tn5 in a chromosomal location different from that of hha. Both kinds of transpositional events appeared to restore the function of the hha gene.
Badenas
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Departamento de Microbiologia, Facultad de Biologia, Universidad de Barcelona, Spain.
Madrid
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Juárez
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D001483:Base Sequence; D015139:Blotting, Southern; D015342:DNA Probes; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D006460:Hemolysin Proteins / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation
D015342:DNA Probes; D004251:DNA Transposable Elements; D006460:Hemolysin Proteins