Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia; School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia.
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia.
Int J Biol Macromol. 2017 Oct;103:648-655. doi: 10.1016/j.ijbiomac.2017.05.082. Epub 2017 May 17.
Acinetobacter baumannii produces a variety of capsular polysaccharides (CPS) via genes located at the chromosomal K locus and some KL gene clusters include genes for the synthesis of specific sugars. The structures of K11 and K83 CPS produced by isolates LUH5545 and LUH5538, which carry related KL11a and KL83 gene clusters, respectively, were established by sugar analysis and one- and two-dimensional H and C NMR spectroscopy. Both CPS contain l-rhamnose (l-Rha) and 6-deoxy-l-talose (l-6dTal), and both KL gene clusters include genes for dTDP-l-Rhap synthesis and a tle (talose epimerase) gene encoding an epimerase that converts dTDP-l-Rhap to dTDP-l-6dTalp. The K11 and K83 repeat units are the same pentasaccharide, consisting of d-glucose, l-Rha, l-6dTal, and N-acetyl-d-glucosamine, except that l-6dTal is 2-O-acetylated in K83. However, the K units are linked differently, with l-Rha in the main chain in K11, but as a side-branch in K83. KL11 and KL83 encode unrelated Wzy polymerases that link the K units together and different acetyltransferases, though only Atr8 from KL83 is active. The substrate specificity of each Wzy polymerase was assigned, and the functions of all glycosyltransferases were predicted. The CPS structures produced by three closely related K loci, KL29, KL105 and KL106, were also predicted.
鲍曼不动杆菌通过位于染色体 K 位和一些 KL 基因簇中的基因产生多种荚膜多糖（CPS），其中一些 KL 基因簇包含合成特定糖的基因。通过糖分析和一维和二维 H 和 C NMR 光谱学，确定了携带相关 KL11a 和 KL83 基因簇的分离株 LUH5545 和 LUH5538 产生的 K11 和 K83 CPS 的结构。这两种 CPS 都含有 l-鼠李糖（l-Rha）和 6-脱氧-l-塔洛糖（l-6dTal），并且这两个 KL 基因簇都包含 dTDP-l-Rhap 合成基因和 tle（塔洛糖差向异构酶）基因，该基因编码将 dTDP-l-Rhap 转化为 dTDP-l-6dTalp 的差向异构酶。K11 和 K83 重复单元是相同的五糖，由 d-葡萄糖、l-Rha、l-6dTal 和 N-乙酰-d-葡萄糖胺组成，只是 K83 中的 l-6dTal 是 2-O-乙酰化的。然而，K 单元的连接方式不同，K11 中的 l-Rha 是主链，而 K83 中的 l-Rha 是侧链。KL11 和 KL83 编码不相关的 Wzy 聚合酶，将 K 单元连接在一起，并且不同的乙酰基转移酶，尽管只有 KL83 中的 Atr8 是活跃的。每个 Wzy 聚合酶的底物特异性被指定，并且所有糖基转移酶的功能被预测。还预测了三个密切相关的 K 位 KL29、KL105 和 KL106 产生的 CPS 结构。
