Genome Property Definition Page

NameO113(Ec) antigen biosynthesis
DescriptionThe E. coli O113 antigen monomer [1] consists of a branched pentasaccharide of relatively simple galactose and glucose-derived units: [->4)aDGalNAc{(3<-1)bDGal}(1->4)aDGalA(1->3)aDGal(1->3)bDGlcNAc(1->]. Additionally, there is some degree of O-acetylation, the position and extent of which has not yet been determined. The biosynthesis cluster contains four corresponding glycosyltransferases, WbnABDE. Assignments of activity have been predicted at ECODAB, but are not as strong as some and may be in error. These are based on the following homology data and logic: Of the four, WbnE has the strongest similarity to other known enzymes, in the range 37-46% identity, the top four of which are all predicted to carry out the aDGal(1->3)bDGlcNAc reaction. WbnA has the next strongest similarities, in the range 33-37% identity, and although the reactions predicted to be carried out by these homologs are similar to both the aDGalNAc(1->4)aDGalA and the aDGalNAc{(3<-1)bDGal} reactions, one homolog carries out precisely the former reaction and has been experimentally confirmed. Of the remaining two transferases, WbnB and WbnD, both of which show similarities to other glycosyltransferases only in the 26-29% identity range, the correlation between the homologs activities and the ones needed in the O113 cluster are weak and ambiguous. So although ECODAB makes predictions, we do not regard them as sufficiently strong to drive transitive annotations.
JCVI RoleBiosynthesis and degradation of surface polysaccharides and lipopolysaccharides
Literature References
[ 1 ]Parolis H, Parolis LA  The structure of the O-specific polysaccharide from Escherichia coli O113 lipopolysaccharide.  Carbohydr Res. 1995 Feb 17;267(2):263-9.  PMID 7534644
[ 2 ]Paton AW, Paton JC  Molecular characterization of the locus encoding biosynthesis of the lipopolysaccharide O antigen of Escherichia coli serotype O113.  Infect Immun. 1999 Nov;67(11):5930-7.  PMID 10531250
Web ReferencesECODAB:O113

Step NameStep NumRequiredEvidence (Method)Evidence Go Terms
UDP-glucose 4-epimeraseGalEYESTIGR01179 (HMM-CLUST): UDP-glucose 4-epimerase GalE
galactosyl transferase WbnAWbnAYES2897 (RULE_BASE)
galactosyl transferase WbnBWbnBYES2895 (RULE_BASE)
sugar O-acetyl transferase WbnCWbnCYES2894 (RULE_BASE)
galactosyl transferase WbnDWbnDYES2893 (RULE_BASE)
aDGal(1->3)bDGlcNAc transferaseWbnEYES2892 (RULE_BASE)
O113(Ec)-antigen specific transporter (flippase) wzxwzx113YES2898 (RULE_BASE)
O113(Ec)-antigen specific polymerase wzywzy113YES2896 (RULE_BASE)