"A la recherche" of functions for the spore protein SASP-E from Bacillus subtilis

J Microbiol Biotechnol. 2013 Jan;23(1):15-21. doi: 10.4014/jmb.1206.06028.

Abstract

We previously observed that Bacillus subtilis spores from sspE mutants presented a lower germination capacity in media containing high salt concentrations (0.9 M NaCl). This deficiency was attributed to the absence of SASP-E (gamma-type small-acid-soluble protein), rich in osmocompatible amino acids released by degradation. Herein we observed that, in addition, this mutant spore presented a reduced capacity to use L-alanine as germinant (L-ala pathway), required longer times to germinate in calcium dipicolinate (Ca(2+)-DPA), but germinated well in asparagine, glucose, fructose, and potassium chloride (AGFK pathway). Moreover, mild sonic treatment of mutant spores partially recovered their germination capacity in L-ala. Spore qualities were also altered, since sporulating colonies from the sspE mutant showed a pale brownish color, a higher adherence to agar plates, and lower autofluorescence, properties related to their spore coat content. Furthermore, biochemical analysis showed a reduced partition in hexadecane and a higher content of Ca(2+)-DPA when compared with its isogenic wild-type control. Coat protein preparations showed a different electrophoretic pattern, in particular when detected with antibodies against CotG and CotE. The complementation with a wild-type sspE gene in a plasmid allowed for recovering the wild-type coat phenotype. This is the first report of a direct involvement of SASP-E in the spore coat assembly during the differentiation program of sporulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus subtilis / growth & development
  • Bacillus subtilis / metabolism
  • Bacillus subtilis / physiology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Gene Deletion
  • Genetic Complementation Test
  • Protein Multimerization*
  • Spores, Bacterial / growth & development
  • Spores, Bacterial / metabolism
  • Spores, Bacterial / physiology*

Substances

  • Bacterial Proteins
  • spore-specific proteins, Bacillus