Incompatibility of Escherichia coli rho mutants with plasmids is mediated by plasmid-specific transcription

Tsai Kun Li, Yuri A. Panchenko, Marc Drolet, Leroy F. Liu

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4 Citations (Scopus)


The Escherichia coli rho-15 mutant (deficient in transcription termination) is known to be incompatible with pBR322 and other plasmids (J. S. Fassler, G. F. Arnold, and I. Tessman, Mol. Gen. Genet. 204:424-429, 1986). We show that failure of pBR322 to transform rho-15 is mediated by transcription from the tet promoter and readthrough from the tet gene into the rom region. Using an isopropyl-β-D-thiogalactopyranoside-inducible promoter to replace the tet promoter, we have demonstrated that plasmid- specific transcription inhibits growth of the rho-15 host, possibly due to the expression of the Rom protein. The involvement of Rom protein in pBR322- rho-15 incompatibility is further indicated by the following two experiments. (i) Functional inactivation of the rom gene in pBR322 enabled plasmids to transform E. coli rho-15. (ii) Specific overexpression of the rom gene abolished plasmid transformation into E. coli rho-15. An rpoB8(Ts) mutant RNA polymerase which compensated for the termination defect in E. coli rho-15 also restored plasmid-host compatibility, suggesting that Rom-mediated plasmid-host incompatibility is linked to a defect in transcription termination.

Original languageEnglish
Pages (from-to)5789-5794
Number of pages6
JournalJournal of Bacteriology
Issue number18
Publication statusPublished - Sept 1997
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology


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