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Phosphate groups in lipopolysaccharides of Salmonella typhimurium rfaP mutants
Author(s) -
Helander Ilkka M.,
Kilpeläinen Ilkka,
Vaara Martti
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00572-3
Subject(s) - oligosaccharide , phosphate , lipid a , mutant , chemistry , salmonella , biochemistry , bacteria , biology , genetics , gene
Lipopolysaccharides (LPS) of Salmonella typhimurium rfaP mutants and of a galE strain as a control were subjected to analysis by 31 P‐NMR in order to assess the location of phosphate groups. This was done to obtain direct proof for our earlier finding by chemical analysis that phosphate was lacking in the core oligosaccharide part of the mutant LPS, whereas the core oligosaccharide normally contains several phosphate groups. Such phosphate deficiency has been associated with the increased susceptibility of the rfaP mutants to hydrophobic antibiotics and detergents. Analysis of the de‐ O ‐acylated LPS derivatives of S. typhimurium rfaP strains SH7770, SH8551, and SH8572 by 31 P‐NMR revealed an almost total lack of phosphate groups in the core oligosaccharide part, the LPS phosphates being largely accounted for by the two monophosphate monoesters of lipid A, linked to positions C‐1 and C‐4′ of the lipid A backbone. Core oligosaccharide‐linked phosphates were detected in minor proportions only, indicating the presence of some normally phosphorylated core oligosaccharide, due to the inherently leaky nature of the mutation.