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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lipopolysaccharide (LPS) molecule is an important virulence determinant in Klebsiella pneumoniae. Studies on the serotype O1 LPS were initiated to determine the basis for antigenic heterogeneity previously observed in the O1 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 O-side chain polysaccharides of serotype O1 LPS contained a mixture of two structurally distinct D-galactan polymers. The repeating unit structures of these two polymers were identified as [----3)-beta-D-Galf-(1----3)-alpha-D-Galp-(1----] (D-galactan I) and [----3)-alpha-D-Galp-(1----3)-beta-D-Galp-(1----] (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 O1 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 Klebsiella 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 coli K-12 strains carrying the his region of K. pneumoniae were constructed by chromosome mobilization with RP4::mini-Mu. In these transconjugants, the O antigen encoded by the his-linked rfb 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 rfb cluster.
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PMID:Expression of two structurally distinct D-galactan O antigens in the lipopolysaccharide of Klebsiella pneumoniae serotype O1. 170 83

The rfb gene encoding the proteins responsible for the synthesis of the repeating units (O side-chain) of Escherichia coli 09 lipopolysaccharide was cloned into a conjugative plasmid RP4::miniMu and was expressed in E. coli K-12.
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PMID:Cloning and analysis of rfb gene synthesizing the mannan 0 side chain of Escherichia coli 09 lipopolysaccharide. 218 49

Recent studies have shown that determinants for the production of O antigen lipopolysaccharide in Shigella dysenteriae 1 are distributed over two distinct genetic elements, the chromosome and a 9 kb plasmid designated pHW400. In this communication, we describe the cloning of all determinants necessary for S. dysenteriae 1 O antigen production in E. coli K-12 and their combination in a single plasmid. An RP4::miniMu R-prime plasmid, R-prime 40, containing the his-rfb (histidine biosynthesis-lipopolysaccharide biosynthesis) gene region of the Shigella dysenteriae 1 chromosome was generated. E. coli K-12 bacteria containing R-prime 40 and pSS8, a transposon Tn5-tagged derivative of pHW400, produced lipopolysaccharide indistinguishable from that of S. dysenteriae 1. Small DNA fragments containing the rfb gene cluster and the rfp gene were subcloned from R-prime 40 and pSS8 and subsequently combined in vector pACYC184 to produce pSS37. This latter plasmid when introduced by transformation into E. coli K-12 provoked the formation of S. dysenteriae 1 O-specific lipopolysaccharide, a feature that suggests it may be useful in the construction of LPS-based live vaccines against the Shiga bacillus.
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PMID:Cloning of the rfb gene region of Shigella dysenteriae 1 and construction of an rfb-rfp gene cassette for the development of lipopolysaccharide-based live anti-dysentery vaccines. 246 31

Escherichia coli K30 produces a thermostable group I capsular polysaccharide. Two classes of mutants were isolated with defects in the synthesis or expression of capsule. The most common mutant phenotype was acapsular (K-), with no K-antigen synthesized. A second class of mutants, termed Ki or intermediate forms, produced colonies which were indistinguishable from those of acapsular forms yet K-antigenicity was expressed. Previous studies had demonstrated that E. coli strains that produce K30 antigen synthesize a lipopolysaccharide (LPS) fraction that is recognised by monoclonal antibodies against the K30 antigen. Synthesis of this LPS fraction was not affected in Ki forms. The results of morphological examination, LPS analysis and phage sensitivity studies are consistent with the interpretation that the defect in Ki strains results from an inability to polymerize the K30 antigen. Using plasmid pULB113 (RP4::mini-Mu), mutations resulting in both K- and Ki phenotypes were localized near the his region of the chromosome.
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PMID:Mutants of Escherichia coli O9:K30 with altered synthesis and expression of the capsular K30 antigen. 269 13

R-prime plasmids carrying the pyrE-rfa-cysE region of the chromosome of Salmonella typhimurium were isolated by using the vector pULB113 (RP4::mini-Mu). One of the R-prime plasmids was used as a source of DNA to clone the rfa genes for lipopolysaccharide synthesis to pBR322. The following three hybrid plasmids were constructed: pKZ15, with a 4.0-kilobase EcoRI fragment of S. typhimurium DNA, containing the rfaG gene; pKZ27, a 9-kilobase BglII fragment with the rfaG, rfaB, and rfaI genes; and pKZ26, a 7.7-kilobase HindIII fragment with the rfaG, rfaB, rfaI, and rfaJ genes. We propose that these cloned genes code for four glycosyltransferases used for synthesis of the lipopolysaccharide core region (rfaG for glucosyltransferase I; rfaI for galactosyltransferase I; rfaB for galactosyltransferase II; and rfaJ for glucosyltransferase II). For all four genes, mutants which lacked the appropriate enzyme activity were complemented by the plasmids to give completed core lipopolysaccharide with O (somatic) side chains; for rfaG, rfaB, and rfaI, mutants gave restored or even amplified levels of the appropriate glycosyltransferase in in vitro assays. We show that the order of genes in the region is pyrE-rfaG-(rfaB-rfaI)-rfaJ-rfaL-rfaF -cysE.
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PMID:Cloning of rfaG, B, I, and J genes for glycosyltransferase enzymes for synthesis of the lipopolysaccharide core of Salmonella typhimurium. 315 16

The RfaH protein controls the transcription of a specialized group of Escherichia coli and Salmonella operons that direct the synthesis, assembly and export of the lipopolysaccharide core, exopolysaccharide, F conjugation pilus and haemolysin toxin. RfaH is a specific regulator of transcript elongation; its loss increases transcription polarity in these operons without affecting initiation from the operon promoters. The operons of the RfaH-dependent regulon contain a short conserved 5' sequence, the ops element, deletion of which increases operon polarity to an extent similar to that caused by loss of RfaH. The ops element is also present upstream of polysaccharide gene clusters of Shigella flexneri, Yersinia enterocolitica, Vibrio cholerae and Klebsiella pneumoniae and the RP4 fertility operon of Pseudomonas aeruginosa, suggesting that this is a widely spread control system. The mechanistic coupling of RfaH and the ops element has been demonstrated in vitro and in vivo, and we suggest that the ops element recruits RfaH and potentially other factors to the RNA polymerase complex, modifying the complex to increase its processivity and allowing transcription to proceed over long distances.
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PMID:RfaH and the ops element, components of a novel system controlling bacterial transcription elongation. 942 23