title: Acetylation of O-specific lipopolysaccharides from Shigella flexneri 3a and 2a occurs in Escherichia coli K-12 carrying cloned S. flexneri 3a and 2a rfb genes.
abstract: Most of the Shigella flexneri O-specific serotypes result from O-acetyl and/or glucosyl groups added to a common O-repeating unit of the lipopolysaccharide (LPS) molecule. The genes involved in acetylation and/or glucosylation of S. flexneri LPS are physically located on lysogenic bacteriophages, whereas the rfb cluster contains the biosynthesis genes for the common O-repeating unit (D.A.R. Simmons and E. Romanowska, J. Med. Microbiol. 23:289-302, 1987). Using a cosmid cloning strategy, we have cloned the rfb regions from S. flexneri 3a and 2a. Escherichia coli K-12 containing plasmids pYS1-5 (derived from S. flexneri 3a) and pEY5 (derived from S. flexneri 2a) expressed O-specific LPS which reacted immunologically with S. flexneri polyvalent O antiserum. However, O-specific LPS expressed in E. coli K-12 also reacted with group 6 antiserum, indicating the presence of O-acetyl groups attached to one of the rhamnose components of the O-repeating unit. This was confirmed by measuring the amounts of acetate released from purified LPS samples and also by the chemical removal of O-acetyl groups, which abolished group 6 reactivity. The O-acetylation phenotype was absent in an E. coli strain with an sbcB-his-rfb chromosomal deletion and could be restored upon conjugation of F' 129, which carries sequences corresponding to a portion of the deleted region. Our data demonstrate that E. coli K-12 strains possess a novel locus which directs the O acetylation of LPS and is located in the sbcB-rfb region of the chromosomal map.
mesh_terms: D000107:Acetylation; D000117:Acetylglucosamine; D000372:Agglutination Tests; D000907:Antibodies, Bacterial / Q000276:immunology; D002240:Carbohydrate Sequence; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D000939:Epitopes; D004926:Escherichia coli / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics*; D008070:Lipopolysaccharides / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D019081:O Antigens; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D015183:Restriction Mapping; D012210:Rhamnose / Q000031:analogs & derivatives; D012763:Shigella flexneri / Q000235:genetics*
chemical_list: D000907:Antibodies, Bacterial; D000939:Epitopes; D008070:Lipopolysaccharides; D019081:O Antigens; D011135:Polysaccharides, Bacterial; D012210:Rhamnose; D000117:Acetylglucosamine