Phosphotransferases in bacterial cell wall biosynthesis

细菌细胞壁生物合成中的磷酸转移酶

• 批准号: BB/J015016/1
• 负责人: Richard Lewis
• 金额: $ 45.95万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FJ015016%2F1
• 关键词: Phosphotransferases; bacterial; cell; wall; biosynthesis

The cell wall is an important, and sometimes overlooked, key facet of one of two major branches of bacteria, called the Gram-positives. Without the cell wall, the Gram-positive bacterial cell would become seriously compromised and the soluble contents of the cell would burst through the rather fragile single lipid membrane that encompasses the cell. The cell would die. The cell wall of these organisms comprises two major components, a mesh-like structure of cross-linked strands of peptidoglycan, which becomes attached to long, polymeric carbohydrates, such as the teichoic acids and the capsule. Both peptidoglycan and teichoic acid play key roles - peptidoglycan provides the necessary physical protection from the osmotic pressure of the cell, and its synthesis is co-ordinated with the growth of the cell so that the peptidoglycan is not limiting. Teichoic acids are required for the interaction of bacteria with their surroundings, for the regulation of other enzyme activities on the cell surface and contribute to the maintenance of the overall shape of the cell. Capsules are often required to protect pathogens against components of the immune system. Teichoic acids, capsular polysaccharides and peptidoglycan are synthesised in multiple, independent steps by a series of specific biological catalysts, called enzymes. Teichoic acids and capsular polysaccharides are synthesised inside the cell, whereas peptidoglycan is synthesised outside the cell. The lipid-linked teichoic acid precursor is transported across the membrane and transferred onto peptidoglycan, although the precise stage in the synthesis of peptidoglycan that this transfer step occurs is unknown. Only this attachment of the major anionic polymers (wall teichoic acid and capsule) to peptidoglycan builds the final, functional cell wall essential for bacterial lifestyle. We have discovered the enzyme family, called LCP, which performs this transfer step, and in this proposal we seek to understand the molecular basis for its biochemical properties. Specifically, we will study the biochemical reaction catalysed by these enzymes and determine high resolution 3-dimensional structures of the enzymes in complex with the reaction components. We will also develop the synthesis, catalysed by the known enzymes in the pathway, of teichoic acid building blocks that will be better suited to the study of the biochemistry of these proteins than the commercially available components that we have used thus far.

细胞壁是细菌的两个主要分支之一（称为革兰氏阳性细菌）的一个重要但有时被忽视的关键方面。如果没有细胞壁，革兰氏阳性细菌细胞将变得严重受损，并且细胞的可溶性内容物将突破包围细胞的相当脆弱的单一脂质膜。细胞会死亡。这些生物体的细胞壁包括两个主要成分，肽聚糖交联链的网状结构，其附着于长的聚合碳水化合物，如磷壁酸和胶囊。肽聚糖和磷壁酸都起着关键作用-肽聚糖提供了必要的物理保护以免受细胞渗透压的影响，并且其合成与细胞的生长相协调，使得肽聚糖不受限制。磷壁酸是细菌与其周围环境相互作用所必需的，用于调节细胞表面上的其他酶活性，并有助于维持细胞的整体形状。胶囊通常需要保护病原体免受免疫系统成分的侵害。磷壁酸、荚膜多糖和肽聚糖通过一系列特定的生物催化剂（称为酶）在多个独立步骤中合成。磷壁酸和荚膜多糖在细胞内合成，而肽聚糖在细胞外合成。脂质连接的磷壁酸前体被转运穿过膜并转移到肽聚糖上，尽管该转移步骤发生在肽聚糖合成中的精确阶段是未知的。只有这种主要的阴离子聚合物（壁磷壁酸和胶囊）与肽聚糖的连接才能构建细菌生活方式所必需的最终功能性细胞壁。我们已经发现了酶家族，称为LCP，它执行这个转移步骤，在这个提议中，我们试图了解其生化特性的分子基础。具体而言，我们将研究这些酶催化的生化反应，并确定与反应组分复合的酶的高分辨率三维结构。我们还将开发由已知酶催化的磷壁酸结构单元的合成，这将比我们迄今为止使用的市售组分更适合于这些蛋白质的生物化学研究。

项目成果

The Redundancy of Peptidoglycan Carboxypeptidases Ensures Robust Cell Shape Maintenance in Escherichia coli.

• DOI: 10.1128/mbio.00819-16
• 发表时间: 2016-06-21
• 期刊: mBio
• 影响因子: 6.4
• 作者: Peters K;Kannan S;Rao VA;Biboy J;Vollmer D;Erickson SW;Lewis RJ;Young KD;Vollmer W
• 通讯作者: Vollmer W