FIGURE 1.

Structures of the E. coli polymannose O-PSs and organization of the corresponding biosynthetic gene clusters. A, structures of the O8, O9, and O9a O-PSs. Each polysaccharide contains four structural regions (the primer, adaptor, repeat unit domain, and terminal modification), and these are represented in the schematic in the context of the und-PP-linked biosynthetic intermediate. The gene products dedicated to the synthesis of each domain are identified in red. In the structures, GlcpNAc is represented by a blue square and Manp by a green circle following the nomenclature established by the Consortium for Functional Glycomics. B, organization of the corresponding biosynthetic gene clusters.