Expression of the capsular K5 polysaccharide of Escherichia coli: biochemical and electron microscopic analyses of mutants with defects in region 1 of the K5 gene cluster
| Autor: | C Pazzani, Barbara Jann, Klaus Jann, Dorothea Bronner, Veit Sieberth, G Boulnois, I S Roberts |
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| Rok vydání: | 1993 |
| Předmět: |
Bacterial capsule
Immunoelectron microscopy Molecular Sequence Data Restriction Mapping Mutant medicine.disease_cause Microbiology Gene cluster Escherichia coli medicine Cloning Molecular Molecular Biology Bacterial Capsules Antigens Bacterial biology Polysaccharides Bacterial Periplasmic space biology.organism_classification Nucleotidyltransferases Molecular biology Enterobacteriaceae carbohydrates (lipids) Microscopy Electron Carbohydrate Sequence Biochemistry Genes Bacterial Mutagenesis Multigene Family Polysaccharide transport lipids (amino acids peptides and proteins) Research Article Plasmids |
| Zdroj: | Journal of Bacteriology. 175:5984-5992 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.175.18.5984-5992.1993 |
| Popis: | The gene cluster of the capsular K5 polysaccharide, a representative of group II capsular antigens of Escherichia coli, has been cloned previously, and three regions responsible for polymerization and surface expression have been defined (I.S. Roberts, R. Mountford, R. Hodge, K. B. Jann, and G. J. Boulnois, J. Bacteriol. 170:1305-1330, 1988). Region 1 has now been sequenced, and five open reading frames (kpsEDUCS) have been defined (C. Pazzani, C. Rosenow, G. J. Boulnois, D. Bronner, K. Jann, and I. S. Roberts, J. Bacteriol. 175:5978-5983, 1993). In this study, we characterized region 1 mutants by immunoelectron microscopy, membrane-associated polymerization activity, cytoplasmic CMP-2-keto-3-deoxyoctonate (KDO) synthetase activity, and chemical analysis of their K5 polysaccharides. Certain mutations within region 1 not only effected polysaccharide transport (lack of region 1 gene products) but also impaired the polymerization capacity of the respective membranes, reflected in reduced amounts of polysaccharide but not in its chain length. KDO and phosphatidic acid (phosphatidyl-KDO) substitution was found with extracellular and periplasmic polysaccharide and not with cytoplasmic polysaccharide. This and the fact that the K5 polysaccharide is formed in a kpsU mutant (defective in capsule-specific K-CMP-KDO synthetase) showed that CMP-KDO is engaged not in initiation of polymerization but in translocation of the polysaccharide. |
| Databáze: | OpenAIRE |
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