The two-step lysis system of pneumococcal bacteriophage EJ-1 is functional in Gram-negative bacteria: triggering of the major pneumococcal autolysin in Escherichia coli

Authors

  • Eduardo Díaz,

    1. Department of Microbiology, GBF-National Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany,
    2. Department of Molecular Microbiology, Centro de Investigaciones Biológicas (CSIC), Velázquez 144, 28006 Madrid, Spain,
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  • Mathildah Munthali,

    1. Department of Microbiology, GBF-National Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany,
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  • Heinrich Lünsdorf,

    1. Department of Microbiology, GBF-National Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany,
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  • Joachim-Volker Höltje,

    1. Max-Planck Institut für Entwicklungsbiologie, Abteilung Biochemie, Spemannstraße 35, D-72076 Tübingen, Germany
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  • Kenneth N. Timmis

    1. Department of Microbiology, GBF-National Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany,
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Eduardo Díaz E-mail CIB@pinar1.csic.es; Tel. (1) 5611800; Fax (1) 5627518

Abstract

The holin function Ejh of the pneumococcal bacteriophage EJ-1 has been characterized. It shows structural features similar to, and functionally complemented, the prototype member of the holin family. In Escherichia coli and Pseudomonas putida the Ejh product caused cellular death, and changes in cell morphology could be accounted for by lesions in the cytoplasmic membrane. Expression of ejh resulted in the inhibition of growth in a variety of phylogenetically distant bacterial genera, suggesting a broad spectrum of action. Concomitant expression of the ejh and ejl (encodes a lysin) genes led to lysis of E. coli and P. putida cells. Remarkably, the Ejl lysin was able to attack murein from bacteria lacking choline in their sacculi, which suggests that pneumococcal lysins have a broader substrate specificity than previously assumed. Furthermore, the Ejh holin was able to trigger activity of the major pneumococcal autolysin cloned and expressed in E. coli, and this raised new questions about the regulation of this model autolysin. A new function for holins in systems where the phage lysin is supposed to be associated with the membrane is proposed.

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