| Accession | GenProp1036 |
| Name | O11(Ec) antigen biosynthesis |
| Type | METAPATH |
| Description | The E. coli O11 antigen (which is identical to the S. enterica O16 antigen) consists of a branched pentasaccharide with the structure [->4)aDGalNAc{(3<-1)aLFuc}(1->6)aDMan(1->3)aLFuc(1->3)bDGalNAc(1->]. The paper reporting the structure of the antigen [1] also reported a separate disaccharide of unknown provenance. Subsequent genome sequencing of an O11 strain found no evidence of the machinery required to synthesize the reported sugars, so it would appear at the very least to have nothing to do with O11. The four glycosyltransferases WdaDEFG correspond to the four glycosidic linkages in the antigen monomer. WdaG shows a high similarity (>95% identity) to enzymes of uncharacterized specificity from the E. coli O125 and O41 antigens. The structure of O41(Ec) is undetermined, but O125(Ec) shares a very similar trisaccharide structure at the end of the monomer with O11(Ec) containing the linkages: [aDMan(1->3)LFuc], and [aLFuc(1->3)DGalNAc]. O11(Ec) also contains a second [aLFuc(1-3)DGalNAc] linkage, but at the branching linkage. Interestingly, WdaD is most similar to the same set of homologs as WdaG, but only at around 35% identity, consistent with it being responsible for the branching linkage. WdaF is similar (~29% identity) to some mannose mannosyltransferases and thus may be responsible for the [aDGalNAc(1->6)DMan] transfer. Based on these three assignments, WdaE can be assigned the final activity [DMan(1->3)aLFuc] by process of elimination. WdaE also has the lowest degree of similarity to other glycosyltransferases and is consistent with L-fucose being quite rare in known E. coil O-antigen structures. |
| Literature References | [ 1 ]Li Y, Perepelov AV, Guo D, Shevelev SD, Senchenkova SN, Shahskov AS, Liu B, Wang L, Knirel YA Structural and genetic relationships of two pairs of closely related O-antigens of Escherichia coli and Salmonella enterica: E. coli O11/S. enterica O16 and E. coli O21/S. enterica O38. FEMS Immunol Med Microbiol. 2011 Apr;61(3):258-68. doi: PMID 21205000
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| Step Name | Step Num | Required | Evidence (Method) | Evidence Go Terms |
|---|
| source of L-fucose | Fuc | YES | GenProp1024 (GENPROP): GDP-L-fucose biosynthesis from GDP-4-keto-6-deoxy-D-mannose
| |
| O11(Ec)-associated UDP-glucose 4-epimerase | GalE | NO | TIGR01179 (HMM-CLUST): UDP-glucose 4-epimerase GalE | |
| source of D-mannose | Man | YES | GenProp1017 (GENPROP): GDP-D-mannose biosynthesis from b-D-fructose-6-phosphate
| |
| putative DGalNAc-a(1,3)-LFuc transferase WdaD | WdaD | YES | | |
| putative LFuc-a(1,3)-DMan transferase WdaE | WdaE | YES | | |
| putative DMan-a(1,6)-DGalNAc transferase | WdaF | YES | | |
| putative DGalNAc-a(1,3)-LFuc transferase WdaG | WdaG | YES | | |
| O11(Ec)-antigen specific transporter (flippase) wzx | wzx11 | YES | | |
| O11(Ec)-antigen specific polymerase wzy | wzy11 | YES | | |
