Genome Property Definition Page

NameO8(Ec) antigen biosynthesis
DescriptionThe 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 PropertyGenProp0913: E. coli O-antigen monomer biosynthesis clusters
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

Step NameStep NumRequiredEvidence (Method)Evidence Go Terms
source of GDP-D-mannoseManYESGenProp1017 (GENPROP): GDP-D-mannose biosynthesis from b-D-fructose-6-phosphate
mannosyltransferase AWbdAYES2852 (RULE_BASE)
mannosyltransferase BWbdBYES2853 (RULE_BASE)
mannosyltransferase CWbdCYES2854 (RULE_BASE)
terminating methyltransferase and chain-length determinant proteinWbdDYES2855 (RULE_BASE)
ABC transporter, transmembrane domainwzmYES2861 (RULE_BASE)
ABC transporter, ATP-binding domain and substrate specificity determinant domainwztYES2859 (RULE_BASE)

Parent Properties
GenProp0913E. coli O-antigen monomer biosynthesis clusters

Sibling Properties
GenProp0932O104(Ec) antigen biosynthesis
GenProp0947O55(Ec) antigen biosynthesis
GenProp0949O111(Ec) antigen biosynthesis
GenProp0953O103(Ec) antigen biosynthesis
GenProp0963O2(Ec) antigen biosynthesis
GenProp1014O5(Ec) antigen biosynthesis
GenProp1042O128(Ec) antigen biosynthesis