Synthesis of capsular polysaccharide at the division septum of Streptococcus pneumoniae is dependent on a bacterial tyrosine kinase

Authors

  • Mafalda X. Henriques,

    1. Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras, Portugal.
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  • Tatiana Rodrigues,

    1. Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras, Portugal.
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  • Madalena Carido,

    1. Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras, Portugal.
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  • Luís Ferreira,

    1. Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras, Portugal.
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  • Sérgio R. Filipe

    Corresponding author
    1. Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras, Portugal.
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  • The authors declare no conflict of interest.

E-mail sfilipe@itqb.unl.pt; Tel. (+351) 21 446 9537; Fax (+351) 21 441 12 77.

Summary

One of the main virulence factors of the pathogenic bacterium Streptococcus pneumoniae is the capsule, present at the bacterial surface, surrounding the entire cell. Virtually all the 90 different capsular serotypes of S. pneumoniae, which vary in their chemical composition, express two conserved proteins, Wzd and Wze, which regulate the rate of the synthesis of capsule. In this work, we show that Wzd, a membrane protein, and Wze, a cytoplasmic tyrosine kinase, localize at the bacterial division septum, when expressed together in pneumococcal cells, without requiring the presence of additional proteins encoded in the capsule operon. The interaction between the two proteins and their consequent septal localization was dependent on a functional ATP binding domain of Wze. In the absence of either Wzd or Wze, capsule was still produced, linked to the cell surface, but it was absent from the division septum. We propose that Wzd and Wze are spatial regulators of capsular polysaccharide synthesis and, in the presence of ATP, localize at the division site, ensuring that capsule is produced in co-ordination with cell wall synthesis, resulting in full encapsulation of the pneumococcal cells.

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