Structure elucidation and study of the biosynthesis of glycosylglycerolipids and teichoic acids of Streptococcus suis and their impact on pathogenicity

猪链球菌糖基甘油脂和磷壁酸的结构解析、生物合成及其对致病性影响的研究

• 批准号: 536971318
• 负责人: Dr. Nicolas Gisch
• 金额: --
• 依托单位: Forschungsgruppe Bioanalytische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/536971318?language=en
• 关键词: Structure; elucidation; study; biosynthesis; glycosylglycerolipids

Teichoic acids (TAs) are essential components of the cell wall of the zoonotic pathogen Streptococcus suis that mainly infects pigs. The structure of its lipoteichoic acid (LTA) was described by us and we could show that S. suis is the first described bacterium, which produces an LTA with two sequential linked structural types. On the one hand we showed the presence of a type I LTA, which is characterized by its poly-glycerolphosphate chain. On the other hand, we were able to show that to this first LTA to some extent further complex, glycosylated building blocks are repetitively added. We already proved the presence of two different classes of these complex LTA molecules within S. suis serotype 2 strains. First experiments using cell-based assays and murine infection models with a genetically modified strain that was no longer capable of glycosylating its LTA indicated the high importance for pathogenicity of this strain. One aim of this project is the screening for other structural LTA variants within other serotypes that frequently occur especially in Germany and North America. Moreover, we will analyze the sequence type (ST) 1 and 25 strains of serotype 2, in which the complex glycosylated LTA have been initially found, with regard to their LTA biosynthesis by deletion of selective genes, especially those putatively involved in the glycosylation process. By this, we aim to gain detailed functional insights. Not much is known about the wall teichoic acid (WTA) and its importance for pathogenicity of S. suis to date. The proof of the presence of a WTA in the S. suis cell wall on the molecular level has not been done yet. In preliminary work, we have been able to show the presence of two distinct cell-wall attached polysaccharides in S. suis. One is the already known capsular polysaccharide, the other polymer displays structural features clearly pointing towards the existence of a WTA. The general chemical structure of this WTA as well as putative ST-specific variants in serotype 2 strains and in other serotypes will be one focus point of this project. The aim is to unravel if the WTA has a completely conserved structure among all strains or if ST-/serotype-specific variants as described for the LTA can be observed. The cell wall of S. suis contains three different glycoglycerolipids, but only one of these represents the glycolipid anchor of the LTA. Glycoglycerolipids of other bacteria have already been described to interact with the C-type receptor Mincle. In this part of project, we will systematically analyze the interaction of Mincle with S. suis glycoglycerolipids and similar molecules of known structure isolated from other bacteria. In summary, the whole project shall provide detailed insights into the structure and biosynthesis pathways of glycoglycerolipids and TAs in S. suis, to be finally able to propose new potential drug targets against this zoonotic pathogen.

磷壁酸 (TA) 是主要感染猪的人畜共患病原体猪链球菌细胞壁的重要成分。我们描述了其脂磷壁酸（LTA）的结构，并且我们可以证明猪链球菌是第一个被描述的细菌，它产生具有两种连续连接的结构类型的LTA。一方面，我们证明了 I 型 LTA 的存在，其特征在于其聚甘油磷酸链。另一方面，我们能够证明，在第一个 LTA 中，在某种程度上重复添加了更复杂的糖基化结构单元。我们已经证明猪链球菌血清型 2 菌株中存在两种不同类别的复杂 LTA 分子。使用基于细胞的测定和小鼠感染模型进行的首次实验表明，该菌株的致病性非常重要，该菌株不再能够糖基化其 LTA。该项目的目标之一是筛选其他血清型中经常出现的 LTA 结构变异，尤其是在德国和北美。此外，我们将分析序列类型（ST）1和血清型2的25个菌株，其中最初发现了复杂的糖基化LTA，通过删除选择性基因，特别是那些推定参与糖基化过程的基因来分析它们的LTA生物合成。通过此，我们的目标是获得详细的功能见解。迄今为止，人们对壁磷壁酸 (WTA) 及其对猪链球菌致病性的重要性知之甚少。尚未在分子水平上证明猪链球菌细胞壁中存在 WTA。在初步工作中，我们已经能够证明猪链球菌中存在两种不同的细胞壁附着多糖。一种是已知的荚膜多糖，另一种聚合物的结构特征清楚地表明 WTA 的存在。该 WTA 的一般化学结构以及血清型 2 菌株和其他血清型中推定的 ST 特异性变体将是该项目的重点之一。目的是弄清楚 WTA 在所有菌株中是否具有完全保守的结构，或者是否可以观察到 LTA 所描述的 ST-/血清型特异性变异。猪链球菌的细胞壁含有三种不同的甘油糖脂，但只有其中一种代表 LTA 的糖脂锚。其他细菌的甘油脂已被描述为与 C 型受体 Mincle 相互作用。在项目的这一部分中，我们将系统地分析 Mincle 与猪链球菌甘油脂以及从其他细菌中分离出的已知结构的类似分子的相互作用。总之，整个项目将提供对猪链球菌中甘油脂和TAs的结构和生物合成途径的详细见解，以便最终能够针对这种人畜共患病原体提出新的潜在药物靶点。