Abnormal excision and transfer of chromosomal segments by a strain of Escherichia coli K-12

Peter L. Bergquist*, Edward A. Adelberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


PB15 is an Hfr strain of Escherichia coli K-12. It arose from an F′ strain carrying a temperature-sensitive F-gal by an event which blocked the detachment of F-gal in the normally reversible integration process. In PB15, the detachment of F-gal by a second mechanism can now be detected: this mechanism results in the excision and transfer of extended chromosomal segments which include the integrated F-gal; the excised segments are inferred to have circularized. Their excision, which is independent of the recA+ allele, occurs at an unusually high rate during conjugation; a mutant F-initiator protein is suggested as the cause of this phenomenon. After their establishment in recipients, the enlarged F-genotes undergo further deletions of included donor genes by a process which is again recA+-independent. In Rec+, but not in Rec−, cells, a high proportion of the deleted fragments are rescued by integration into the recipient's chromosome.
Original languageEnglish
Pages (from-to)119-128
Number of pages10
JournalJournal of Bacteriology
Issue number1
Publication statusPublished - Jul 1972
Externally publishedYes


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