A natural mutant of plasmid RP4 that confers phage resistance and reduced conjugative transfer

Authors

  • Laura B. Kornstein,

    Corresponding author
    1. Sanitary Engineering and Environmental Health Research Laboratory, University of California at Berkeley, Richmond Field Station, Richmond, CA, USA
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  • Virginia L. Waters,

    1. Department of Medicine, U.C.S.D. Medical Center and the Center for Molecular Genetics, University of California at San Diego, San Diego, CA, U.S.A.
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  • Robert C. Cooper

    1. Sanitary Engineering and Environmental Health Research Laboratory, University of California at Berkeley, Richmond Field Station, Richmond, CA, USA
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L.B. Kornstein, 46–46 Bell Blvd. Queens, NY 11361, U.S.A.

Abstract

Abstract A natural isolate of RP4 (PRC#116) acquired from the Stanford University Plasmid Reference Center differed from the wild-type Incompatibility Group P plasmid in several respects. Cells of Escherichia coli harboring PRC#116 were resistant to the IncP pili-specific bacteriophage PRD1 and GU5, and transferred this plasmid at a lower efficiency than the wild-type RP4. Phage sensitivity was restored, and transfer considerably improved in PRC#116+ bacteria transformed with plasmid constructs containing the origin of transfer (ori T region) of RP4. Mutant RP4 plasmids equivalent to PRC#116 were selected at a high frequency from an RP4+E. coli population infected with PRD1 indicating that this RP4 variant may be the product of a very common mutation of the wild-type plasmid.

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