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Sporulation in endospore-forming B. subtilis and C. difficile . Models of the global regulatory process of the four main sporulation specific sigma factors in B. subtilis and C. difficile .

Structural layers of bacterial spores. The main layers of bacterial spore structure are shown and not drawn to scale. The exosporium and spore coat may have sub-layers which are not shown. The exosporium layer is present in some species. Figure has been modified from [ 75 ] with permission from Elsevier.

Tentative models for information flow during spore germination of B. subtilis and C. difficile . Arrows denote the preference of the germinants for the GRs, and upward arrows indicate that cortex hydrolysis might increase the rate of DPA release. Red line indicates that chenodeoxycholate inhibits CspC activation. Question marks indicate that there is suggestive, but no conclusive experimental evidence; AGFK, is a mixture of L-asparagine, glucose, fructose and KCl.

Highlights

  • -
    The Clostridium difficile sporulation process is substantially different than the Bacillus subtilis paradigm.
  • -
    Novel and unidentified proteins are involved in the formation of the C. difficile spore coat layer.
  • -
    C. difficile possesses an exosporium layer that may play a role in pathogenesis.
  • -
    The catalytically dead serine protease, CspC, acts as a bile salt germination receptor.

Acknowledgements

This work was supported by grants from Fondo Nacional de Ciencia y Tecnología de Chile (FONDECYT Grant 1110569), by a grant from the Research Office of Universidad Andres Bello (DI-275-R/13), and by a grant from Fondo de Fomento al Desarrollo Científico y Tecnológico (FONDEF) CA13I10077 to D.P-S. A.S. is a Pew Scholar in the Biomedical Sciences, supported by The Pew Charitable Trusts, and is supported by Award Number R00GM092934 and start-up funds from Award Number P20RR021905 from the National Institute of General Medical Sciences. The content is solely the responsibility of the author(s) and does not necessarily reflect the views of either the Pew Charitable Trusts or the National Institute of General Medical Sciences or the National Institute of Health. J.A.S acknowledges support by the American Heart Association National Scientist Development grant (No. 11SDG7160013), and support by Award Number R21AI07640 from the National Institute of Allergy and Infectious Diseases. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Allergy and Infectious Diseases or the National Institutes of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Footnotes

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