Kenyon Johanna J, Marzaioli Alberto M, Hall Ruth M, De Castro Cristina
School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia.
Department of Chemical Sciences, Complesso Universitario Monte Sant'Angelo, Napoli, Italy.
Glycobiology. 2015 Aug;25(8):881-7. doi: 10.1093/glycob/cwv028. Epub 2015 Apr 28.
The repeat unit of the K12 capsular polysaccharide isolated from the Acinetobacter baumannii global clone 1 clinical isolate, D36, was elucidated by means of chemical and spectroscopical methods. The structure was shown to contain N-acetyl-D-galactosamine (D-GalpNAc), N-acetyl-D-fucosamine and N-acetyl-L-fucosamine linked together in the main chain, with the novel sugar, 5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L-altro-non-2-ulosonic acid (5,7-di-N-acetylacinetaminic acid or Aci5Ac7Ac), attached to D-GalpNAc as a side branch. This matched the sugar composition of the K12 capsule and the genetic content of the KL12 capsule gene cluster reported previously. D-FucpNAc was predicted to be the substrate for the initiating transferase, ItrB3, with the Wzy polymerase making a α-D-FucpNAc-(1 → 3)-D-GalpNAc linkage between the repeat units. The three glycosyltransferases encoded by KL12 are all retaining glycosyltransferases and were predicted to form specific linkages between the sugars in the K12 repeat unit.
通过化学和光谱学方法阐明了从鲍曼不动杆菌全球克隆1临床分离株D36中分离出的K12荚膜多糖的重复单元。结果表明，该结构在主链中含有N-乙酰-D-半乳糖胺（D-GalpNAc）、N-乙酰-D-岩藻糖胺和N-乙酰-L-岩藻糖胺，新型糖5,7-二乙酰氨基-3,5,7,9-四脱氧-L-甘油-L-艾杜糖-2-酮糖酸（5,7-二-N-乙酰不动杆菌氨酸或Aci5Ac7Ac）作为侧链连接到D-GalpNAc上。这与之前报道的K12荚膜的糖组成和KL12荚膜基因簇的遗传内容相匹配。预测D-FucpNAc是起始转移酶ItrB3的底物，Wzy聚合酶在重复单元之间形成α-D-FucpNAc-(1→3)-D-GalpNAc连接。由KL12编码的三种糖基转移酶均为保留型糖基转移酶，预计它们会在K12重复单元中的糖之间形成特定连接。
