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

RUZAL SANDRA M.; BUSTOS, PATRICIA; SANCHEZ-RIVAS, CARMEN

JOURNAL OF MICROBIOLOGY AND BIOTECHNOLOGY

KOREAN SOC MICROBIOLOGY & BIOTECHNOLOGY

Lugar: Seoul ; Año: 2013 vol. 23 p. 15 - 21

1017-7825

We previously observed that Bacillus subtilis spores from sspE mutants presented a lower germination capacity in media containing high salt concentrations (0.9M NaCl). This deficiency was attributed to the absence of SASP-E (gamma-type small-acid-soluble protein), rich in osmocompatibles aminoacids released by degradation. Now we observed that in addition, this mutant spores presented a reduced capacity to use L-alanine as germinant (L-ala pathway), require longer times to germinate in calcium dipicolinate (Ca2+-DPA), but germinated well in asparagine, glucose, fructose and potassium chloride (AGFK pathway). Moreover, mild sonic treatment of mutant spores partially recovers 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, a lower auto-fluorescence, properties related to their spore coat content. Also, biochemical analysis showed a reduced partition in hexadecane and a higher content of Ca2+-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 allows 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.