Expression of two structurally distinct D-galactan O antigens in the lipopolysaccharide of Klebsiella pneumoniae serotype O1

Abstract

The lipopolysaccharide (LPS) molecule is an important virulence determinant in KkebsieUa pneumoniae. Studies on the serotype 01 LPS were initiated to determine the basis for antigenic heterogeneity previously observed in the 01 side chain polysaccharides and to resolve apparent ambiguities in the reported polysaccharide structure. Detailed chemical analysis, involving methylation and 1H-and 13C-nuclear magnetic resonance studies, demonstrated that the 0-side chain polysaccharides of serotype 01 LPS contained a mixture of two structurally distinct D-galactan polymers. The repeating unit structures of these two polymers were(D-Galactan II). D-Galactan I polysaccharides were heterogeneous in size and were detected throughout the sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) profile of 01 LPS. In contrast, D-galactan II was confined to the higher-molecular-weight region. The structures of the two D-galactans were not influenced by simultaneous synthesis of a capsular K antigen. Apparently, neither of the D-galactans constitutes a common antigen widespread in Kkebsiella spp. as determined by immunochemical analysis. Examination of the LPSs in mutants indicated that expression of D-galactan I can occur independently of D-galactan II. Transconjugants of Escherichia coUi K-12 strains carrying the his region of K. pneumoniae were constructed by chromosome mobilization with RP4::mini-Mu. In these transconjugants, the 0 antigen encoded by the his-linked rjb locus was determined to be D-galactan I, suggesting that genes involved in the expression of D-galactan II are not closely linked to the rjb cluster.

O antigen seroepidemiology of Klebsiella clinical isolates and implications for immunoprophylaxis of Klebsiella infections

“…Based on these reactions, the extended O-antigen formula of this strain may be given as O1/2a/core ( Table 1). The lower-and higher-molecular-weight components correspond to two distinct galactose-containing polysaccharides which have been analyzed previously and called D-galactan I and II, respectively (26,49).…”

Unusual Galactofuranose Modification of a Capsule Polysaccharide in the Pathogenic Yeast Cryptococcus neoformans

“…Many mammals, including humans, produce intelectins that recognize monomeric Galf and Galf-containing molecules such as arabinogalactan (22). Galf is also a potent antigenic determinant in diverse extracellular molecules, including the lipopolysaccharides of Gram-negative bacteria (23)(24)(25) and the galactomannans of aspergilli (7).…”

UDP-galactofuranose Precursor Required for Formation of the Lipopolysaccharide O Antigen of Klebsiella pneumoniae Serotype O1 Is Synthesized by the Product of the rfbDKPO1 Gene

“…3478); Fax: 519-837-1802; E-mail: cwhitfie@ micro.uoguelph.ca. 1 The abbreviations used are: LPS, lipopolysaccharide; UDP-Galp or UDP-galactopyranose, uridine 5Ј-(trihydrogen diphosphate) PЈ-␣-D-galactopyranosyl ester; UDP-Galf or UDP-galactofuranose, uridine 5Ј-(trihydrogen diphosphate) PЈ-␣-D-galactofuranosyl ester; Galf-1,2-P, ␣-D-galactofuranose cyclic 1,2-(hydrogen phosphate); HPAEC, high performance anion exchange chromatography; COSY, correlated spectroscopy; TOCSY, total correlation spectroscopy; HMQC, heteronuclear multiple-quantum coherence; PAGE, polyacrylamide gel electrophoresis; S-LPS, smooth LPS; HPLC, high performance liquid chromatography.…”

“…In the genus Klebsiella, there exists a family of structurally related galactose-containing O polysaccharides. These are based on a backbone structure consisting of a disaccharide O-repeat unit [33)-␤-D-Galf-(133)-␣-D-Galp- (13] known as D-galactan I (1). Variations in O antigens arise from addition of side-chain ␣-D-Galp (2) and O-acetyl (2, 3) residues, or by addition of domains of varying structure (1, 4 -6).…”