PMID:10574995
| Citation |
Feldman, MF, Marolda, CL, Monteiro, MA, Perry, MB, Parodi, AJ and Valvano, MA (1999) The activity of a putative polyisoprenol-linked sugar translocase (Wzx) involved in Escherichia coli O antigen assembly is independent of the chemical structure of the O repeat. J. Biol. Chem. 274:35129-38 |
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| Abstract |
During O antigen lipopolysaccharide (LPS) synthesis in bacteria, transmembrane migration of undecaprenylpyrophosphate (Und-P-P)-bound O antigen subunits occurs before their polymerization and ligation to the rest of the LPS molecule. Despite the general nature of the translocation process, putative O-antigen translocases display a low level of amino acid sequence similarity. In this work, we investigated whether complete O antigen subunits are required for translocation. We demonstrate that a single sugar, GlcNAc, can be incorporated to LPS of Escherichia coli K-12. This incorporation required the functions of two O antigen synthesis genes, wecA (UDP-GlcNAc:Und-P GlcNAc-1-P transferase) and wzx (O-antigen translocase). Complementation experiments with putative O-antigen translocases from E. coli O7 and Salmonella enterica indicated that translocation of O antigen subunits is independent of the chemical structure of the saccharide moiety. Furthermore, complementation with putative translocases involved in synthesis of exopolysaccharides demonstrated that these proteins could not participate in O antigen assembly. Our data indicate that recognition of a complete Und-P-P-bound O antigen subunit is not required for translocation and suggest a model for O antigen synthesis involving recognition of Und-P-P-linked sugars by a putative complex made of Wzx translocase and other proteins involved in the processing of O antigen. |
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| Keywords |
Agglutination; Bacterial Proteins; Blotting, Western; Carrier Proteins/genetics; Carrier Proteins/metabolism; Electrophoresis, Polyacrylamide Gel; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Hexosyltransferases/metabolism; Lipid A/metabolism; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism; Mutagenesis; O Antigens/biosynthesis; O Antigens/metabolism; Oligosaccharides/metabolism; Recombinant Proteins/metabolism; Spectrometry, Mass, Fast Atom Bombardment |
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