Genome Property Definition Page

NameO1(Ec) antigen biosynthesis
DescriptionThe E. coli O1A antigen is a branched pentasaccharide with the structure [->3)aLRha{(2<-1)bDManNAc}(1->3)aLRha(1->3)bLRha(1->4)bDGlcNAc(1->] [1]. A structure with different boundaries for the repeating unit was reported [], but is less likely considering the genomic evidence (the lack of a candidate GlcNAc transferase) and the propensity for a GlcNAc residue to be the final one in the monomer structure of many E. coli O-antigens. Slightly different structures have been reported for the O1B and O1C variants [2]. It has been suggested that the epitopic commonality is related to the branching ManNAc group [3]. The genomic data for this property derived from the APEC O1 strain, for which a detailed sub-typing is not available. Confusing matters further, the two genes which should be responsible for the pendant ManNAc group (WecB and a putative N-acetyl-D-mannosyltransferase) appear to be disrupted by single frameshifts in this genome (and both were excluded from the GenBank record). To determine rules for these two genes, the reconstructed whole genes were used as references. Although there are three rhamnosyltransferase-dependent linkages expected in the O1 structures, only two ramnosyltransferase genes are observed. Two of these linkaged are essentially identical and could easily be catalyzed by the same enzyme.
JCVI RoleBiosynthesis and degradation of surface polysaccharides and lipopolysaccharides
Literature References
[ 1 ]Baumann H, Jansson PE, Kenne L, Widmalm G  Structural studies of the Escherichia coli O1A O-polysaccharide, using the computer program CASPER.  Carbohydr Res. 1991 Apr 2;211(1):183-90.  PMID 1773429
[ 2 ]Gupta DS, Shashkov AS, Jann B, Jann K  Structures of the O1B and O1C lipopolysaccharide antigens of Escherichia coli.  J Bacteriol. 1992 Dec;174(24):7963-70.  PMID 1281148
Web ReferencesThe O1 antigen of Escherichia coli: structural characterization of the O1A1-specific polysaccharide. B. Jann, A.S. Shashkovb, D.S. Gupta, S.M. Panasenko, K. Jann, Carbohydrate Polymers, Volume 18, Issue 1, 1992, Pages 5157.

Step NameStep NumRequiredEvidence (Method)Evidence Go Terms
source of N-acetyl-D-mannosamineD-ManNAcYESGenProp0975 (GENPROP): biosynthesis of UDP-N-acetyl-D-mannosamine (UDP-ManNAc)
putative D-ManNAc transferaseGT-1YES2948 (RULE_BASE)
O1(Ec)-associated L-rhamnose transferaseGT-2YES2946 (RULE_BASE)
O1(Ec)-associated L-rhamnose transferaseGT-3YES2945 (RULE_BASE)
source of L-rhamnoseL-RhaYESGenProp0183 (GENPROP): dTDP-L-rhamnose biosynthesis from dTDP-4-dehydro-L-rhamnose
O1(Ec)-antigen transporter (flippase) wzxwzx01YES2949 (RULE_BASE)
O1(Ec)-antigen polymerase wzywzy01YES2947 (RULE_BASE)