Evidence of bar Minigene Expression and tRNA2IleSequestration as Peptidyl-tRNA2Ileduring Lambda Bacteriophage Development

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 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{tRNA}_{2}^{\mathrm{Ile}}\) \end{document} as \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{pep}-\mathrm{tRNA}_{2}^{\mathrm{Ile}}\) \end{document} . Either \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{tRNA}_{2}^{\mathrm{Ile}}\) \end{document} or Pth may reverse these effects. In this paper we present evidence that both barI and barII minigenes are translatable elements that sequester \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{tRNA}_{2}^{\mathrm{Ile}}\) \end{document} as \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{pep}-\mathrm{tRNA}_{2}^{\mathrm{Ile}}\) \end{document} . 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 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{tRNA}_{2}^{\mathrm{Ile}}\) \end{document} is sequestered as \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{pep}-\mathrm{tRNA}_{2}^{\mathrm{Ile}}\) \end{document} during lambda phage development.