Selfish restriction modification genes: Resistance of a resident R/M plasmid to displacement by an incompatible plasmid mediated by host killing

Yasuhiro Naito, Taku Naito, Ichizo Kobayashi

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Previous work from this laboratory demonstrated that plasmids carrying a type II restriction-modification gene complex are not easily lost from their bacterial host because plasmid-free segregant cells are killed through chromosome cleavage. Here, we have followed the course of events that takes place when an Escherichia coli recBC sbcA strain carrying a plasmid coding for the PaeR71 restriction-modification (R/M) gene complex is transformed by a plasmid with an identical origin of replication. The number of transformants that appeared was far fewer than with the restriction-minus (r-) control. Most of the transformants were very small. After prolonged incubation, the number and the size of the colonies increased, but this increase never attained the level of the r- control. Most of the transformed colonies retained the drug-resistance of the resident, r+ m+ plasmid. These results indicate that post-segregational host killing occurs when a plasmid bearing an R/M gene complex is displaced by an incompatible plasmid. Such cell killing eliminates the competitor plasmid along with the host and, thus, would allow persistence of the R/M plasmid in the neighboring, clonal host cells in nature. This phenomenon is reminiscent of mammalian apoptosis and other forms of altruistic cell death strategy against infection. This type of resistance to displacement was also studied in a wild type Escherichia coli strain that was normal for homologous recombination (rec+). A number of differences between the recBC sbcA strain and the rec+ strain were observed and these will be discussed.

Original languageEnglish
Pages (from-to)429-436
Number of pages8
JournalBiological Chemistry
Volume379
Issue number4-5
DOIs
Publication statusPublished - 1998 Jan 1

Keywords

  • Apoptosis
  • Homologous recombination
  • Plasmid
  • Programmed cell death
  • Selfish gene

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Clinical Biochemistry

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