SsgA-like proteins determine the fate of peptidoglycan during sporulation of Streptomyces coelicolor

Authors

  • Elke E. E. Noens,

    1. Department of Biochemistry, Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, the Netherlands.
    2. Department of Molecular Cell Biology, Leiden University Medical Center, Leiden University, 2300 RA Leiden, the Netherlands.
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  • Vassilis Mersinias,

    1. School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK.
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  • Bjørn A. Traag,

    1. Department of Biochemistry, Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, the Netherlands.
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  • Colin P. Smith,

    1. School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK.
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  • Henk K. Koerten,

    1. Department of Molecular Cell Biology, Leiden University Medical Center, Leiden University, 2300 RA Leiden, the Netherlands.
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  • Gilles P. van Wezel

    Corresponding author
    1. Department of Biochemistry, Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, the Netherlands.
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E-mail g.wezel@chem.leidenuniv.nl; Tel. (+31) 71 5274310; Fax (+31) 71 5274340.

Summary

During developmental cell division in sporulation-committed aerial hyphae of streptomycetes, up to a hundred septa are simultaneously produced, in close harmony with synchromous chromosome condensation and segregation. Several unique protein families are involved in the control of this process in actinomycetes, including that of the SsgA-like proteins (SALPs). Mutants for each of the individual SALP genes were obtained, and high-resolution and fluorescence imaging revealed that each plays an important and highly specific role in the control of the sporulation process, and their function relates to the build-up and degradation of septal and spore-wall peptidoglycan. While SsgA and SsgB are essential for sporulation-specific cell division in Streptomyces coelicolor, SsgC–G are responsible for correct DNA segregation/condensation (SsgC), spore wall synthesis (SsgD), autolytic spore separation (SsgE, SsgF) or exact septum localization (SsgG). Our experiments paint a picture of a novel protein family that acts through timing and localization of the activity of penicillin-binding proteins and autolysins, thus controlling important steps during the initiation and the completion of sporulation in actinomycetes.

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