The Chemistry and Biology of Galactofuranose Residues

性状（由申请方提供）：呋喃半乳糖（Galf）残留物与许多微生物（包括分枝杆菌）的毒力或活力有关。该研究的目的是了解Galf残基掺入分枝杆菌细胞壁的机制。我们将研究这一过程中两个关键酶的结构、催化机制和功能：黄素酶尿苷-5 '-二磷酸（UDP）-吡喃半乳糖苷酶（Glf或UGM）和半乳糖基呋喃糖基转移酶GlfT 2。本申请的三个具体目标如下。目的1是了解黄素酶UGM的作用机制。阐明UGM的催化机制将提高我们对黄素酶的不同化学性质的理解，提供对细胞壁生物合成的化学基础的洞察，并指导这种必需酶的抑制剂的产生。目的2是产生有效的和细胞可渗透的UGM抑制剂，可用作细胞壁生物合成的探针，并作为开发新的抗分枝杆菌剂的线索。目的3是研究酶GlfT 2，其催化由交替的1，5-和1，6-连接的Galf残基组成的半乳聚糖聚合物的合成。我们将测试聚合是否是进行性的，探索单个酶如何产生两个区域异构糖键，并确定如何控制聚合物长度。这些研究将阐明分枝杆菌中半乳聚糖生物合成和多糖生物合成的基本机制。在追求这些目标时，我们将采用有机化学、糖生物学、碳水化合物化学、化学酶学、结构生物学、微生物学和化学生物学的方法和思想。重要性：拟议研究的结果将为半乳聚糖聚合物的组装提供新的见解，半乳聚糖聚合物是分枝杆菌细胞壁的重要组成部分。他们还将解决生物系统如何在没有模板的情况下控制聚合物长度的基本问题。这些知识将被应用于开发阻止分枝杆菌细胞生长的小分子。这些药物将作为分枝杆菌细胞壁生物合成的有价值的探针，并作为开发新的抗分枝杆菌药物的先导。 公共卫生相关性：该研究项目的重点是了解分枝杆菌细胞壁生物合成的基本步骤。分枝杆菌引起许多疾病，包括结核病（TB）。结核病每年造成约170万人死亡，目前的治疗方法正在失败。该项目的目标是了解分枝杆菌细胞壁生物合成中的关键步骤，这些步骤不是任何现有药物的目标，并找到可以开发新型药物的抑制剂。

DESCRIPTION (provided by applicant): Galactofuranose (Galf) residues have been implicated in the virulence or viability of many microbes, including mycobacteria. The goal of the proposed research is to understand the mechanisms underlying Galf residue incorporation into the mycobacterial cell wall. We shall investigate the structure, catalytic mechanism, and function of two key enzymes in this process: the flavoenzyme uridine-5'-diphosphate (UDP)-galactopyranose mutase (Glf or UGM) and the galactosylfuranosyltransferase GlfT2. The three Specific Aims of this application follow. Aim 1 is to understand the mechanism of the flavoenzyme UGM. Elucidating the catalytic mechanism UGM will enhance our understanding of the diverse chemistry of the flavoenzymes, provide insight into the chemistry underlying cell wall biosynthesis, and guide the generation of inhibitors of this essential enzyme. Aim 2 is to generate potent and cell-permeable inhibitors of UGM that can be used as probes of cell wall biosynthesis and as leads for the development of new antimycobacterial agents. Aim 3 is to investigate the enzyme GlfT2, which catalyzes the synthesis of a galactan polymer composed of alternating 1,5- and 1,6-linked Galf residues. We shall test whether the polymerization is processive, explore how a single enzyme generates two regioisomeric sugar linkages, and determine how polymer length is controlled. These investigations will illuminate the mechanisms underlying galactan biosynthesis in mycobacteria and the biosynthesis of polysaccharides, in general. In pursuing these Aims, we shall employ methods and ideas from organic chemistry, glycobiology, carbohydrate chemistry, chemical enzymology, structural biology, microbiology, and chemical biology. Significance: The results of the proposed research will provide new insights into the assembly of the galactan polymer, an essential component of the mycobacterial cell wall. They also will address the fundamental question of how biological systems control polymer length in the absence of a template. This knowledge will be applied to develop small molecules that block mycobacterial cell growth. Such agents will serve as valuable probes of mycobacterial cell wall biosynthesis and as leads for the development of new antimycobacterial drugs. PUBLIC HEALTH RELEVANCE: This research project is focused on understanding essential steps in the biosynthesis of the mycobacterial cell wall. Mycobacteria cause a number of diseases, including tuberculosis (TB). TB causes about 1.7 million deaths each year, and current therapies are failing. The goal of this project is to understand key steps in mycobacterial cell wall biosynthesis that are not targeted by any current drugs and find inhibitors from which new types of drugs could be developed.