Analysis of the genetic locus encompassing a cell wall polysaccharide (CWPS) biosynthesis operon of eight strains of Lactococcus lactis, identified as belonging to the same CWPS type C genotype, revealed the presence of a variable region among the strains examined. The results allowed the identification of five subgroups of the C type named subtypes C1 to C5. This variable region contains genes encoding glycosyltransferases that display low or no sequence homology between the subgroups. In this study, we purified an acidic polysaccharide from the cell wall of L. lactis 3107 (subtype C2) and confirmed that it is structurally different from the previously established CWPS of subtype C1 L. lactis MG1363. The CWPS of L. lactis 3107 is composed of pentasaccharide repeating units linked by phosphodiester bonds with the structure 6-α-Glc-3-β-Galf-3-β-GlcNAc-2-β-Galf-6-α-GlcNAc-1-P. Combinations of genes from the variable region of subtype C2 were introduced into a mutant of subtype C1 L. lactis NZ9000 deficient in CWPS biosynthesis. The resulting recombinant mutant synthesized a polysaccharide with a composition characteristic of that of subtype C2 L. lactis 3107 and not wild-type C1 L. lactis NZ9000. By challenging the recombinant mutant with various lactococcal phages, we demonstrated that CWPS is the host cell surface receptor of tested bacteriophages of both the P335 and 936 groups and that differences between the CWPS structures play a crucial role in determining phage host range.

Type a flagellins from two strains of Pseudomonas aeruginosa, strains PAK and JJ692, were found to be glycosylated with unique glycan structures. In both cases, two sites of O-linked glycosylation were identified on each monomer, and these sites were localized to the central, surface-exposed domain of the monomer in the assembled filament. The PAK flagellin was modified with a heterogeneous glycan comprising up to 11 monosaccharide units that were O linked through a rhamnose residue to the protein backbone. The flagellin of JJ692 was less complex and had a single rhamnose substitution at each site. The role of the glycosylation island gene cluster in the production of each of these glycosyl moieties was investigated. These studies revealed that the orfA and orfN genes were required for attachment of the heterologous glycan and the proximal rhamnose residue, respectively.Protein glycosylation in prokaryotic organisms is now a wellestablished process, particularly in cell surface-associated or secreted molecules (5). Very recently, a number of examples of glycosylated surface proteins of bacterial pathogens have been described, including surface proteins of Streptococcus sanguis and Mycobacterium tuberculosis (11,14), the TIB adhesin of Escherichia coli (TIB) (4, 26), flagellum and periplasmic proteins of Campylobacter (12,40,43,44), flagellum proteins of Helicobacter pylori (35), an outer membrane protein of Chlamydia (24), and pilus proteins of Neisseria species (37) and Pseudomonas aeruginosa (8). However, information about the structures of the linked glycans found on prokaryotic glycoproteins, the mechanistic basis of the process, and the biological role of the process in bacterial pathogenesis is still limited.P. aeruginosa is an opportunistic pathogen which causes lifethreatening infections in immunocompromised individuals and burn wound victims and chronic infections in patients with cystic fibrosis (6). This organism produces a number of virulence factors, including toxins, secreted proteins, surface carbohydrates (mucoid exopolysaccharide and lipopolysaccharide [LPS]), and pili (18,27). A more recent addition to the list of putative virulence factors is the single, polar, nonsheathed flagellum of this organism, which traditionally is considered a motility organ but whose chief constituent, flagellin, is now known to be a potent stimulator of the inflammatory response via Toll-like receptor 5 (19). The flagellin protein can be classified in one of two major types, type a or type b, based on molecular weight and reactivity with specific antisera (1, 25). The type a flagellin appears to have two major subtypes of proteins, designated subtypes A1 and A2 (3). Type a flagellins have been shown to be heterologous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and to have molecular masses ranging from 45 to 52 kDa, while type b flagellins appear to have conserved sequences and a molecular mass of 53 kDa. The central domain of type a flagellin is described as hypervariable, and this is be...

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Shigellosis, an enteric disease, is on the World Health Organization's priority prevention list. In one study, the Shigella sonnei O-specific polysaccharide (O-SP)-protein conjugate showed 72% protection against disease in Israeli army recruits exposed to high rates (8 -14%) of infection. The protection was related to vaccineinduced IgG anti-O-SP levels. Synthetic oligosaccharides of Shigella dysenteriae type 1, bound by their reducing ends to a carrier protein (''sun''-type configuration), induced significantly higher antibody levels than the native O-SP bound to protein by multiplepoint attachments (''lattice''-type configuration). Attempts to synthesize the S. sonnei O-SP based oligosaccharides were not successful. Here, we describe the isolation, characterization, and conjugation of low-molecular-mass O-SP-core (O-SPC) fragments. The O-SPC fragments were bound by their reducing ends similar to the preparation of the synthetic S. dysenteriae type 1 conjugates. The O-SPC conjugates used oxime linkages between the terminal Kdo residues at the reducing ends of the S. sonnei saccharides and aminooxy linkers bound to BSA or a recombinant diphtheria toxin. The coupling reaction was carried out at a neutral pH and room temperature. IgG antibody levels induced in young outbred mice by the S. sonnei O-SPC conjugates were significantly higher then those elicited by the O-SP conjugates. Accordingly, we propose to evaluate clinically these conjugates.lipopolysaccharide ͉ glycoconjugate ͉ vaccine ͉ Kdo ͉ IgG