Acinetobacter baumannii K13 and K73 capsular polysaccharides differ only in K-unit side branches of novel non-2-ulosonic acids: di- N-acetylated forms of either acinetaminic acid or 8-epiacinetaminic acid

摘要

AbstractStructures of capsular polysaccharides ofAcinetobacter baumanniiisolates carrying KL13 and KL73 gene clusters were established. The closely related KL73 and KL13 gene clusters differ only by one gene in the module responsible for synthesis of the non-2-ulosonic acids. The K13 and K73 polysaccharides differ only in a single side-chain sugar, which is either 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-altro- or -d-glycero-l-altro-non-2-ulosonic acid [di-N-acetylated forms of acinetaminic acid (Aci5Ac7Ac) or 8-epiacinetaminic acid (8eAci5Ac7Ac), respectively].Display OmittedThe KL13 also is closely related to the KL12 gene cluster, which contains a differentwzygene encoding the K unit polymerase. Accordingly, the otherwise near identical K units are linked differently via an α-d-FucpNAc-(1?→?4)-d-Galplinkage in K13 and K73 or an α-d-FucpNAc-(1?→?3)-d-GalpNAc linkage in K12. This finding confirms the predicted substrate of the ItrB3 initiating transferase asd-FucpNAc. Glycosyltransferases predicted to catalyse the linkage of