Lipid modification of prelipoproteins is dispensable for growth in vitro but essential for virulence in Streptococcus pneumoniae

A Delta lgt (Lgt. lipoprotein diacylglyceryl transferase) isogenic mutant was obtained which indicates that lgt is not essential for cell growth in vitro, like in the Gram-positive bacterium Bacillus subtilis, but unlike in the proteobacteria Escherichia coli and Salmonella typhimurium. The mutation was transduced to a virulent strain. A 5 log attenuation was observed in a respiratory tract model of infection. Metabolic labeling by [U-C-14]palmitate revealed the presence of right to ten lipoproteins in the wild-type strain only. with molecular masses between 15 and 80 kDa. Our findings suggest a major difference in the role of lipoproteins in Gram-positive bacteria versus the proteobacteria. (C) 2001 Federation of European Microbiological societies. Published by Elsevier Science B.V. All rights reserved.