ABSTRACT
Lambda bacteriophage development is impaired in Escherichia coli cells defective for peptidyl (pep)-tRNA hydrolase (Pth). Single-base-pair mutations (bar
−) that affect translatable two-codon open reading frames named bar minigenes (barI or barII) in the lambda phage genome promote the development of this phage in Pth-defective cells (rap cells). When the barI minigene is cloned and overexpressed from a plasmid, it inhibits protein synthesis and cell growth in rap cells by sequestering
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as
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. Either
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or Pth may reverse these effects. In this paper we present evidence that both barI and barII minigenes are translatable elements that sequester
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as
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. In addition, overexpression of the barI minigene impairs the development even of bar
− phages in rap cells. Interestingly, tRNA or Pth may reestablish lambda phage development. These results suggest that lambda bar minigenes are expressed and
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is sequestered as
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during lambda phage development.