N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia.
Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Australia.
Carbohydr Res. 2019 Sep 1;483:107745. doi: 10.1016/j.carres.2019.107745. Epub 2019 Jul 12.
The K8 and K54 capsular polysaccharides were isolated from Acinetobacter baumannii BAL 097 and RCH52, respectively, and studied by sugar analysis, partial acid hydrolysis and selective solvolysis with CFCOH in the presence of 2-methyl-1-propanol, along with 1D and 2D H and C NMR spectroscopy. The following structures of related branched tetrasaccharide repeats (K units) of the polysaccharides were established: where Leg indicates 5,7-diamino-3,5,7,9-tetradeoxy-d-glycero-d-galacto-non-2-ulosonic (legionaminic) acid and R indicates (R)-3-hydroxybutanoyl or acetyl in the ratio ~2.5:1. The sequences of the KL8 and KL54 capsule gene clusters were closely related. The difference in the acyl group at O-7 on the sidechain legionaminic acid is due to differences in two genes in the legionaminic acid biosynthesis cluster. The wzy genes encoding the K unit polymerases are also different and make different linkages between the K units, allowing the first sugar of both K units to be identified as d-GlcpNAc. The shared Gtr20 glycosyltransferase, also encoded in KL63, forms the α-l-FucpNAc-(1 → 3)-d-GlcpNAc linkage, and Gtr19 was predicted to form α-d-GalpNAc-(1 → 3)-l-FucpNAc. Gtr18 from KL8 is 75% identical to Gtr108 from KL54 and both would link the Leg derivative to d-GalpNAc. Hence the genes present at the K locus were consistent with the composition and structures of the K8 and K54 capsular polysaccharides.
K8 和 K54 荚膜多糖分别从鲍曼不动杆菌 BAL 097 和 RCH52 中分离得到，通过糖分析、部分酸水解和在 2-甲基-1-丙醇存在下用 CFCOH 的选择性溶剂解以及 1D 和 2D H 和 C NMR 光谱进行了研究。建立了多糖相关支化四糖重复（K 单元）的以下结构：其中 Leg 表示 5,7-二氨基-3,5,7,9-四脱氧-d-甘油-d-半乳糖-non-2-ulosonic（军团菌酸）酸，R 表示（R）-3-羟基丁酰基或乙酰基，比例约为 2.5:1。KL8 和 KL54 荚膜基因簇的序列密切相关。侧链军团菌酸 O-7 上酰基的差异归因于军团菌酸生物合成簇中两个基因的差异。编码 K 单元聚合酶的 wzy 基因也不同，在 K 单元之间形成不同的键，从而可以确定两个 K 单元的第一个糖都是 d-GlcpNAc。共享的 Gtr20 糖基转移酶，也在 KL63 中编码，形成 α-l-FucpNAc-(1 → 3)-d-GlcpNAc 键，而 Gtr19 预测形成 α-d-GalpNAc-(1 → 3)-l-FucpNAc。KL8 中的 Gtr18 与 KL54 中的 Gtr108 有 75%的同一性，两者都将衍生的 Leg 与 d-GalpNAc 连接。因此，K 位上存在的基因与 K8 和 K54 荚膜多糖的组成和结构一致。
