Effect of depletion of FtsY on spore morphology and the protein composition of the spore coat layer in Bacillus subtilis

Bacillus subtilis FtsY is a homolog of the alpha -subunit of mammalian sign al recognition particle (SRP) receptor and is essential for protein translo cation and vegetative cell growth. An FtsY conditional null mutant (strain ISR39) can express fts Y during the vegetative stage but not during spore f ormation. Spores of ISR39 have the same resistance to heat and chloroform a s the wild-type. while their resistance to lysozyme is reduced. Electron mi croscopy showed that the outer coat of spores was incompletely assembled. T he coat protein profile of the fts Y mutant spores was different from that of wild-type spores. The amounts of CotA, and CotE were reduced in spore co at proteins of fts Y mutant spores and the molecular mass of CotB was reduc ed. In addition. CotA, CotB, and CotE are present in normal form at T-8 of sporulation in fts Y mutant cells. These results suggest that FtsY has a pi votal role in assembling coat proteins onto the coat layer during spore mor phogenesis. (C) 2001 Federation of European Microbiological Societies. Publ ished by Elsevier Science B.V. All rights reserved.