Structural and biological characterization of a capsular polysaccharide produced by Staphylococcus haemolyticus
Structural and biological characterization of a capsular polysaccharide produced by Staphylococcus haemolyticus
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DOI：
10.1128/jb.01648-07
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发表时间：
2008-03-01
影响因子：
3.2
通讯作者：
Lee, Jean C.
中科院分区：
文献类型：
--
作者：
Flahaut, Sigrid;Vinogradov, Evgeny;Lee, Jean C.
溶血葡萄球菌JCSC 1435基因组的DNA序列揭示了一个由13个基因串联组成的假定的荚膜操纵子。前7个基因（capABCDEFG（Sh））与金黄色葡萄球菌cap 5或cap 8基因座显示>= 57%的相似性。然而，capHIJKLM（Sh）基因是S.溶血性链球菌的基因，包括编码推定的翻转酶、氨基转移酶、两种糖基转移酶和转录调节子的基因。通过免疫电子显微镜观察，在生长的后指数阶段收获的细菌上的胶囊样物质很明显。缺失帽区的JCSC 1435突变体的电子显微镜照片缺乏囊样物质。两种菌株都产生少量的表面相关物质，这些物质与聚谷氨酸抗体反应。S.从7株临床分离的溶血性链球菌中的4株中扩增出溶血性链球菌cap基因。这些菌株中有三种产生血清学交叉反应性荚膜多糖。体外试验表明，无囊突变株显示更大的生物膜形成，但更容易补体介导的调理吞噬杀伤比亲本菌株。从S.溶血性链球菌菌株JCSC 1435显示三糖重复单元：-3-α-L-FucNAc-3-（2-NAc-4-N-Asp-2，4，6-三脱氧-β-D-Glc）-4-α-D-GlcNAc-。该结构在葡萄球菌多糖中是独特的，因为其组成包括具有天冬氨酸作为N-酰基取代基的三脱氧糖残基。
The DNA sequence of the genome of Staphylococcus haemolyticus JCSC1435 revealed a putative capsule operon composed of 13 genes in tandem. The first seven genes (capABCDEFG(Sh)) showed >= 57% similarity with the Staphylococcus aureus cap5 or cap8 locus. However, the capHIJKLM(Sh) genes are unique to S. haemolyticus and include genes encoding a putative flippase, an aminotransferase, two glycosyltransferases, and a transcriptional regulator. Capsule-like material was readily apparent by immunoelectron microscopy on bacteria harvested in the postexponential phase of growth. Electron micrographs of a JCSC1435 mutant with a deleted cap region lacked the capsule-like material. Both strains produced small amounts of surface-associated material that reacted with antibodies to polyglutamic acid. S. haemolyticus cap genes were amplified from four of seven clinical isolates of S. haemolyticus from humans, and three of these strains produced a serologically cross-reactive capsular polysaccharide. In vitro assays demonstrated that the acapsular mutant strain showed greater biofilm formation but was more susceptible to complement-mediated opsonophagocytic killing than the parent strain. Structural characterization of capsule purified from S. haemolyticus strain JCSC1435 showed a trisaccharide repeating unit: -3-alpha-L-FucNAc-3-(2-NAc-4-N-Asp-2,4,6-trideoxy-beta-D-Glc)-4-alpha-D-GlcNAc-. This structure is unique among staphylococcal polysaccharides in that its composition includes a trideoxy sugar residue with aspartic acid as an N-acyl substituent.