Accession | GenProp1018 |
Name | O8(Ec) antigen biosynthesis |
Type | METAPATH |
Description | The O8 monomer is a linear trisaccharide consisting of three D-mannose units [-->3)-b-D-Man-(1-->2)-a-D-Man-(1-->2)-a-D-Man-(1-->]. This units are handled in an ABC-transporter dependent process in which polymerization occurs on the cytoplasmic face of the plasma membrane followed by transport (flipping) of the undecaprenyl-linked full-length polymer. The O8 antigen is reported to consist of 9 monomer units terminated by a single D-Man3Me residue. There are three mannosyltransferase enzymes involved in this process (MtfABC; in the identical Klebsiella O5, WbdABC). MtfB and MtfC are typical single-domain GT enzymes, while MtfA is much larger consisting of 3 distinct domains, each from the GT1 superfamily (cdd03809, cdd03822 and cdd03801). MtfC and MtfB are believed to be involved in the synthesis of the post-priming adaptor, a disaccharide of mannose that precedes the regular monomer repeat pattern. MtfA and B are responsible for the monomer synthesis, with the long MtfA having a likely patterning role. The methyltransferase MtfD is the terminator and chain-length determinant, acting when the chain is the appropriate length by blocking the O3 position of the growing polymer. The ABC transporter appears to require the presence of the methylated final residue to move the polymer to the periplasmic side of the membrane. |
Parent Property | GenProp0913: E. coli O-antigen monomer biosynthesis clusters
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Literature References | [ 1 ]Clarke BR, Cuthbertson L, Whitfield C Nonreducing terminal modifications determine the chain length of polymannose O antigens of Escherichia coli and couple chain termination to polymer export via an ATP-binding cassette transporter. J Biol Chem. 2004 Aug 20;279(34):35709-18. Epub 2004 Jun 7. PMID 15184370 [ 2 ]Jansson PE, Lonngren J, Widmalm G, Leontein K, Slettengren K, Svenson SB, Wrangsell G, Dell A, Tiller PR Structural studies of the O-antigen polysaccharides of Klebsiella O5 and Escherichia coli O8. Carbohydr Res. 1985 Dec 15;145(1):59-66. PMID 3912042 |
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