Characterisation of the a-(1-->3) Homopolymer of L-glycero-D-manno-Heptose Units Isolated from the O-Chain Polysaccharide of Agrobacterium radiobacter

This paper provides the first report of the molecular primary structure of the O-chain produced from A. radiobacter group M2-1. The repeating unit was determined, by means of chemical and spectroscopical analyses, to have the following structure: [3)-a-L-glycero-D-manno-heptose-(1-->]n. The relevant feature of this structure is represented by the particular residue involved: L-glycero-D-manno-heptose. This monosaccharide is almost ubiquitous in Gram-negative bacteria, but it is exclusively located in the Core region and only in one other case has it is reported as an O-chain constituent. The knowledge of the chemical structure of the O-chain of A. radiobacter will be useful for comprehending the bacterium-host recognition mechanism at the molecular level.