Targeting bacterial cell division with small molecules and peptides

对抗菌疗法的抗药性仍然是对人类健康的紧迫威胁，尤其是细菌 它们已经对多种抗生素产生了抗药性。为了发现和开发新的抗菌药，重要的是 寻找和开发未得到充分利用的抗生素靶点。一个很有吸引力的候选者是分裂体，即动态蛋白质 将细菌细胞一分为二的复合体。细菌分裂体包含一套高度保守的 协调作用以确保细胞分裂隔膜正确的时间和位置的基本蛋白质 中层牢房。隔膜转肽酶已经是几种广泛使用的β-内酰胺类抗生素的靶点，但没有 其他分裂组蛋白目前也是靶点。FtsZ，一种高度保守的形成聚合物的GTP酶，形成一种 膜相关“Z环”是组织隔膜转肽酶和其他隔膜合成所必需的 酶是作为小分子靶标而被广泛研究的唯一另一种分裂体蛋白质。 和多肽，我们的实验室帮助推进了对FtsZ及其相互作用蛋白的理解已有30年 好几年了。然而，关于小分子如何干扰FtsZ在体内的作用，仍有许多需要了解 分子和细胞水平，以及这些是否能带来潜在的治疗方法。为了解决这个突出的问题 主题，这项提议试图从结构和生理上定义两套不同的有前途的新小 FtsZ的分子抑制剂。第一个是一组两个相关的苯甲酰胺衍生物，由我们的 药物化学合作者，对革兰氏阳性菌和革兰氏阴性菌都有很高的效力 外排泵失效的细菌。这些衍生物被合成成具有优化的结合作用 FtsZ的域间裂隙(IDC)，我们将其称为FtsZ的“跟腱”，是抑制剂的常见靶点。 出乎意料的是，我们发现这两种化合物在革兰氏阳性中通过不同的机制干扰FtsZ 对抗革兰氏阴性细菌，促使人们假设它们破坏了FtsZ组装成 细胞分裂需要适当的缩聚聚合物结构才能进一步进行。这个型号将进行测试。 利用我们实验室独特的跨学科遗传、细胞学和结构生物学方法。这个 第二组小分子抑制物是一对噬菌体多肽，它们已经进化到针对FtsZ AS 是它们裂解周期的一部分。每个肽直接与FtsZ结合，阻断Z环组装，也与FtsZ结合 另一种将FtsZ与细胞膜捆绑在一起的必需分裂体蛋白。它的分子细节 这些结合位点是未知的，但我们假设它们不涉及FtsZ IDC，而是扰动 Z形环采用新颖的双叉机构装配。再一次，我们将运用我们在遗传学方面的广泛专业知识， 显微镜和结构生物学的分裂蛋白质，以阐明这些机制。我们将提供的见解 从拟议的研究中获得的成果应该为小分子未来的治疗潜力奠定基础。 和多肽，可能相互结合或与其他抗生素结合，通过破坏 细胞分裂机制。

Resistance to antibacterial therapies continues to be an urgent threat to human health, particularly bacteria that are already resistant to multiple antibiotics. To discover and develop new antibacterials, it is important to find and exploit under-utilized antibiotic targets. One attractive candidate is the divisome, the dynamic protein complex that splits bacterial cells in two. The bacterial divisome contains a set of highly conserved and essential proteins that act coordinately to ensure the correct timing and placement of the cell division septum at mid-cell. The septal transpeptidase is already a target of several widely used beta-lactam antibiotics, but no other divisome protein is currently targeted. FtsZ, a highly conserved polymer-forming GTPase that forms a membrane-associated "Z ring" required for organizing the septal transpeptidase and other septum-synthesizing enzymes, is the only other divisome protein that has been studied extensively as a target of small molecules and peptides, and our lab has helped to advance the understanding of FtsZ and its interacting proteins for 30 years. Nevertheless, there is still much to learn about how small molecules perturb FtsZ function at the molecular and cellular level and whether these can lead to potential therapeutics. To address this over-arching theme, this proposal seeks to define, structurally and physiologically, two different sets of promising new small molecule inhibitors of FtsZ. The first is a set of two related benzamide derivatives, synthesized by our medicinal chemistry collaborators, that have high potencies against both Gram-positive bacteria and Gramnegative bacteria with disabled efflux pumps. These derivatives were synthesized to have optimized binding to the interdomain cleft (IDC) of FtsZ, a common target of inhibitors that we have termed FtsZ's "Achilles Heel". Unexpectedly, we found that these two compounds perturb FtsZ by distinct mechanisms in Gram-positive versus Gram-negative bacteria, prompting the hypothesis that they disrupt FtsZ's ability to assemble into the proper condensed polymer architecture needed for cell division to progress further. This model will be tested with our laboratory's unique interdisciplinary array of genetic, cytological, and structural biology methods. The second set of small molecule inhibitors is a pair of bacteriophage peptides that have evolved to target FtsZ as part of their lytic cycle. Each peptide binds directly to FtsZ and blocks Z ring assembly, but also binds to another essential divisome protein that tethers FtsZ to the cytoplasmic membrane. The molecular details of these binding sites are unknown, but we hypothesize that they do not involve the FtsZ IDC and instead perturb Z ring assembly by novel two-pronged mechanisms. Again, we will apply our extensive expertise in genetics, microscopy and structural biology of divisome proteins to elucidate these mechanisms. The insights we will gain from the proposed studies should lay a foundation for the future therapeutic potential of small molecules and peptides, potentially in combination with each other or with other antibiotics, to kill bacteria by disrupting the cell division machinery.