Transposition of λplacMu is mediated by the A protein altered at its carboxy-terminal end

Erhard Bremer, Thomas J. Silhavy, George M. Weinstock

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19 Scopus citations


λplacMu phages are derivatives of bacteriophage λ that use the transposition machinery of phage Mu to insert into chromosomal and cloned genes. When inserted in the proper fashion, these phages yield stable fusions to the Escherichia coli lac operon in a single step. We have determined the amount of DNA from the c end of phage Mu present in one of these phages, λplacMu3, and have shown that this phage carries a 3137-bp fragment of Mu DNA. This DNA segment carries the Mu c-end attachment site and encodes the Mu genes cts62, ner+, and gene A lacking 179 bp at its 3′ end (A′). The product of this truncated gene A′ retains transposase activity and is sufficient for the transposition of λplacMu. This was demonstrated by showing that λplacMu derivatives carrying the A am1093 mutation in the A′ gene are unable to transpose by themselves in a Su- strain, but their transposition can be triggered by coinfection with λpMu507(A+ B+). We have constructed several new λplacMu phages that carry the A′ am1093 gene and the kan gene, which confers resistance to kanamycin. Chromosomal insertions of these new phages are even more stable than those of the previously reported λplacMu phages, which makes them useful tools for genetic analysis.

Original languageEnglish (US)
Pages (from-to)177-186
Number of pages10
Issue number1
StatePublished - Nov 15 1988

All Science Journal Classification (ASJC) codes

  • Genetics


  • Mu transposase
  • bacteriophages λ and Mu
  • lacZ fusions
  • recombinant DNA
  • transducing phages


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