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Transient transcriptional activation of the IncI1 plasmid anti‐restriction gene ( ardA ) and SOS inhibition gene ( psiB ) early in conjugating recipient bacteria
Author(s) -
Althorpe Nicola J.,
Chilley Paul M.,
Thomas Angela T.,
Brammar William J.,
Wilkins Brian M.
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01153.x
Subject(s) - biology , plasmid , gene , transcription (linguistics) , promoter , dna , microbiology and biotechnology , genetics , population , rna polymerase , gene expression , rna , linguistics , philosophy , demography , sociology
The ardA gene of the enterobacterial plasmid ColIbP‐9 acts to alleviate restriction of DNA by type I systems, while psiB inhibits induction of the bacterial SOS response. Both genes are transferred early in a round of bacterial conjugation as part of the plasmid leading region. We report here that ardA and psiB are transcribed transiently after their conjugative transport into the recipient cell. Transcript levels, monitored by competitive reverse transcription–polymerase chain reaction (RT–PCR) amplification of RNA templates, started to increase about 5 min after the initiation of conjugation in a cell population and probably before the first round of plasmid transfer was completed. Genetic evidence is given that the expression of ardA and psiB is activated when the genes enter the recipient cell on the transferring plasmid strand. It is proposed that these and other leading region genes function to promote the establishment of the immigrant plasmid in the new host and are expressed by transcription from promoters active only in single‐stranded DNA.