鲍曼不动杆菌 NIPH 329 和 SDF 产生的 K46 和 K5 荚膜多糖具有相关结构，侧链非塔罗糖醛酸由噬菌体编码的 O-乙酰基转移酶 4-O-乙酰化。
The K46 and K5 capsular polysaccharides produced by Acinetobacter baumannii NIPH 329 and SDF have related structures and the side-chain non-ulosonic acids are 4-O-acetylated by phage-encoded O-acetyltransferases.
机构信息
Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Australia.
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia.
出版信息
PLoS One. 2019 Jun 20;14(6):e0218461. doi: 10.1371/journal.pone.0218461. eCollection 2019.
Acinetobacter baumannii isolate NIPH 329 carries a novel capsular polysaccharide (CPS) gene cluster, designated KL46, that is closely related to the KL5 locus in A. baumannii isolate SDF but includes genes for synthesis of 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic (di-N-acetylpseudaminic) acid (Pse5Ac7Ac) instead of the corresponding D-glycero-D-galacto isomer (di-N-acetyllegionaminic acid) (Leg5Ac7Ac). In agreement with the genetic content of KL46, chemical studies of the K46 CPS produced by NIPH 329 revealed a branched tetrasaccharide repeat (K unit) with an overall structure the same as K5 from SDF but with â-Pse5Ac7Ac replacing α-Leg5Ac7Ac. As for K5, the K46 unit begins with d-GalpNAc and includes α-d-GlcpNAc-(1→3)-d-GalpNAc and α-d-Galp-(1→6)-d-GlcpNAc linkages, formed by Gtr14 and Gtr15 glycosyltransferases, respectively. The Gtr94K46 glycosyltransferase, which is related to Gtr13K5, links Pse5Ac7Ac to d-Galp in the growing K unit via a â-(2→6) linkage. Nearly identical Wzy enzymes connect the K46 and K5 units via a α-D-GalpNAc-(1→3)-α-D-Galp linkage to form closely related CPSs. Both Pse5Ac7Ac in K46 and Leg5Ac7Ac in K5 are acetylated at O4 but no acetyltransferase gene is present in KL46 or KL5. Related acetyltransferases were found encoded in the NIPH 329 and SDF genomes, but not in other strains carrying an unacetylated Pse or Leg derivative in the CPS. The genes encoding the acetyltransferases were in different putative phage genomes. However, related acetyltransferases were rare among the >3000 publically available genome sequences.
鲍曼不动杆菌分离株 NIPH 329 携带一个新型荚膜多糖（CPS）基因簇，命名为 KL46，该基因簇与鲍曼不动杆菌分离株 SDF 的 KL5 基因座密切相关，但包含合成 5,7-二乙酰氨基-3,5,7,9-四脱氧-l-甘油-l-甘露诺-2-酮基（二-N-乙酰伪氨基酸）（Pse5Ac7Ac）的基因，而不是相应的 D-甘油-D-半乳糖异构体（二-N-乙酰莱格氨基酸）（Leg5Ac7Ac）。与 KL46 的遗传内容一致，对 NIPH 329 产生的 K46 CPS 的化学研究表明，分支四糖重复（K 单元）具有与 SDF 中的 K5 相同的整体结构，但用 α-Pse5Ac7Ac 代替 α-Leg5Ac7Ac。与 K5 一样，K46 单元以 d-GalpNAc 开头，包含 α-d-GlcpNAc-(1→3)-d-GalpNAc 和 α-d-Galp-(1→6)-d-GlcpNAc 键，分别由 Gtr14 和 Gtr15 糖基转移酶形成。与 Gtr13K5 相关的 Gtr94K46 糖基转移酶通过 α-(2→6)键将 Pse5Ac7Ac 连接到生长中的 K 单元中的 d-Galp 上。几乎相同的 Wzy 酶通过 α-D-GalpNAc-(1→3)-α-D-Galp 键将 K46 和 K5 单元连接起来，形成密切相关的 CPS。K46 中的 Pse5Ac7Ac 和 K5 中的 Leg5Ac7Ac 均在 O4 位乙酰化，但 KL46 或 KL5 中不存在乙酰转移酶基因。在 NIPH 329 和 SDF 基因组中发现了编码这些乙酰转移酶的基因，但在其他携带 CPS 中未乙酰化的 Pse 或 Leg 衍生物的菌株中没有发现。编码这些乙酰转移酶的基因位于不同的假定噬菌体基因组中。然而，在 >3000 个公开可用的基因组序列中，相关的乙酰转移酶很少见。
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