Genome Property Definition Page  NameO121(Ec) antigen
biosynthesis DescriptionThe E. coli O121 antigen monomer is a
linear tetrasaccharide with the structure [->3)bDQui4NGlyAc(1-
>4)aDGalNAcAN(1->4)aDGalNAcA(1->3)aDGlcNAc(1->]. The
4-aminoquinovose sugar is also known as viosamine and the NGlyAc
is an acetylglycylamido group; GalNAcA is N-acetylgalturonic
acid, and GalNAcAN is N-acetylgalacturonamide. Additionally, the
DGalNAcAN is reported to be 60% O-acetylated at the 3-position.
Three glycosyltransferases are present in the sequenced O121(Ec)
cluster, WbqEHI. WbqI shares 47% identity with the WfaH enzyme
from the O138(Ec) antigen cluster, and O138 shares the
[DGlcNAc-a-1,3-DGalNAcA] reaction. WbqE shares 37% identity with
WfbE from the O123(Ec) antigen cluster, and O123 also includes a
4-substituted quinovose sugar in the first position of the
monomer, although the incorporated amino acid is alanine instead
of glycine. By process of elimination, the WbqH enzyme is
assigned to the middle linkage. The N-acety