Mycobacterium Tuberculosis Cell Wall Assembly

 描述(申请人提供)：结核分枝杆菌(Mtb)的细胞膜是这种细菌病原体许多生理和致病特征的基础，也是许多抗结核药物的敏感和耐药部位。尽管分枝杆菌是革兰氏阳性细菌，但它的独特之处在于，它的细胞壁不含(脂)磷壁酸，而是含有一种被称为阿拉伯半乳糖(AG)的杂多糖，它与肽聚糖(PG)共价结合。到目前为止，负责这两个大分子共价结合的细胞壁连接酶(S)还没有明确的定义。尽管AG和壁磷壁酸(WTA)之间存在根本的结构差异，但分枝杆菌中连接AG和PG的单位的结构与许多革兰氏阳性细菌中参与WTA和PG共价连接的连接子有相似之处。最近发现，在枯草芽孢杆菌和金黄色葡萄球菌中，广泛存在的LytR-Cps2A-PSR(LCP)家族的酶可能是介导WTA-PG附着的连接酶。我们在Mtb H37Rv基因组中鉴定了三个LCP样蛋白，其中一个定位于AG生物合成基因簇。我们建议结合遗传和生化方法来确定这三个LCP同源物是否是长期寻找的分枝杆菌细胞壁连接酶，并确定它们的治疗潜力。特别是，我们将测试两种新型抗菌化合物，卡普扎霉素B和CPZEN-45，这是与日本东京微生物化学研究所(BIKAKEN，日本东京)合作的产品，它们抑制分枝杆菌细胞壁组装中机械相似的酶(分别为mray和WECA)，是否可能成为未来开发针对分枝杆菌细胞壁组装的抑制剂的有前途的支架。与WTA连接酶的情况类似，我认为Mtb的连接酶(S)可能与其他壁蛋白相互作用(S)，以协调细胞壁的合成与细胞的伸长和细胞分裂。结核分枝杆菌连接酶(S)的特性 也代表着朝着阐明生理学的这一关键方面迈出的重要的第一步 分枝杆菌的研究和未来旨在针对细胞延长和分裂的创新治疗策略的设计。

 DESCRIPTION (provided by applicant): The cell envelope of Mycobacterium tuberculosis (Mtb) is the basis of many of the physiological and pathogenic features of this bacterial pathogen and the site of susceptibility and resistance to many anti- tuberculosis drugs. In spite of being Gram-positive bacteria, mycobacteria are unique in having a cell wall devoid of (lipo)teichoic acids and instead containing a heteropolysaccharide known as the arabinogalactan (AG) covalently attached to peptidoglycan (PG). To this date, the cell wall ligase(s) responsible for the covalent attachment of these two macromolecules has/have defied definition. Despite the fundamental structural differences that exist between AG and wall teichoic acids (WTA), the structure of the unit linking AG to PG in mycobacteria shares similarities with the linker involved in the covalent attachment of WTA to PG in many Gram-positive bacteria. Enzymes of the widespread LytR-Cps2A-Psr (LCP) family were recently identified as the likely ligases mediating WTA-PG attachment in Bacillus subtilis and Staphylococcus aureus. We identified three LCP-like proteins in the genome of Mtb H37Rv, one of them mapping to an AG biosynthetic gene cluster. We here propose to use a combination of genetic and biochemical approaches to determine whether these three LCP homologs are the long sought mycobacterial cell wall ligases and to define their therapeutic potential. In particula, we will test whether two novel antibacterial compounds, caprazamycin B and CPZEN-45, products of a collaboration with the Institute of Microbial Chemistry (BIKAKEN, Tokyo, Japan) that inhibit mechanistically similar enzymes in mycobacterial cell wall assembly (MraY and WecA, respectively) may represent promising scaffolds for the future development of inhibitors targeting the assembly of the mycobacterial cell wall. Similar to the situation with WTA ligases, i is likely that the ligase(s) of Mtb interact(s) with other wall proteins to coordinate cell wall synthesis with cell elongation and cell division. The characterization of Mtb's ligase(s) therefore also represents an important first step toward the elucidation of this key aspect of the physiology of mycobacteria and the future design of innovative therapeutic strategies aimed at targeting cell elongation and division.