"The molecular mechanisms of asymmetric cell division in mycobacteria."

摘要 结核病(TB)是一种由结核分枝杆菌(Mtb)引起的细菌感染，现在是主要原因 死于一种单一的感染性病原体。其中一个原因是结核分枝杆菌亚群甚至可以存活下来。 长时间的化疗，阻碍了疾病的治愈。这些存活的细胞是表型耐受的，但不是 对抗生素治疗有基因抗药性。因此，基因相同的细菌表现出不同的能力 表型是结核病治疗的一个重大障碍。更好地理解分子 这种现象背后的机制可能会导致结核病和其他分枝杆菌的治疗进展 感染。这种异质性很大程度上始于分枝杆菌细胞分裂。每一次分枝杆菌 生育出具有不同特征的女儿。我们最近发现，这个过程是 基因编码的。删除单个基因，我们将其命名为LAMA，会导致细胞生长和分裂 更对称，对某些抗生素更统一地敏感。喇嘛的功能及其如何 中介不对称增长和分裂是未知的。在这里，我们建议研究分子 喇嘛的职能。我们公布的和初步的数据显示，喇嘛定位于分裂的地点，在那里它 抑制新的生长杆的成熟。此外，我们已经将LAMA与磷酸化联系起来 一种必需的肽聚糖合成酶的状态，并发现其自身的定位受 磷酸化。这导致了我们的假设，即喇嘛动态地中断未知的通信 在磷酸化过程中，在完成分裂和延伸的多蛋白质复合体之间传递- 依赖的态度。为了验证该模型，我们提出了以下目标：(1)定义通信中继器 在分裂和伸长复合体之间；以及，(2)动态映射导致 不对称。我们的创新是研究一种分枝杆菌特异性蛋白质，这种蛋白质在 基因相同的种群。我们将利用我们在先进成像技术方面的专业知识来实现这一目标 与更传统的方法相结合。这些目标的成功实现将导致以下假设 喇嘛的功能可以用分子和生物化学方法来测试。此外，我们的结果将 进一步加深了我们对细胞分裂介导的异质性的分子基础的理解，这种异质性具有深远的意义。 对结核病治疗的影响。例如，识别分子机制(S) 导致细菌亚群能够更好地存活抗生素治疗将使我们能够设计药物 针对异质性的战略。这样的干预可以更快地治疗结核病，这将是 极大地帮助减轻全球结核病的负担。

Abstract Tuberculosis (TB), a bacterial infection caused by Mycobacterium tuberculosis (Mtb), is now the leading cause of death by a single infectious agent. One reason for this is that subpopulations of Mtb cells can survive even lengthy chemotherapy, preventing cure of disease. These surviving cells are phenotypically tolerant, but not genetically resistant, to antibiotic therapy. Thus, the ability of genetically identical bacteria to display different phenotypes is a significant obstacle for the treatment of TB. A better understanding of the molecular mechanisms underlying this phenomenon could lead to therapeutic advances for TB and other mycobacterial infections. Much of the heterogeneity begins at mycobacterial cell division. Every time a mycobacterium divides it produces daughters with different characteristics. We have recently discovered that this process is genetically encoded. Deleting a single gene, which we have named lamA, leads to cells that grow and divide more symmetrically and are more uniformly susceptible to certain antibiotics. The function of LamA and how it mediates asymmetric growth and division are unknown. Here, we propose to investigate the molecular function of LamA. Our published and preliminary data show that LamA localizes to the site of division, where it inhibits the maturation of the new growth poles. In addition, we have connected LamA to the phosphorylation state of an essential peptidoglycan synthase, and have discovered that its own localization is regulated by phosphorylation. This leads to our hypothesis that LamA dynamically interrupts an unknown communication relay between the multi-protein complexes that accomplish division and elongation, in a phosphorylation- dependent manner. To test this model, we propose the following aims: (1) define the communication relay between the division and elongation complexes; and, (2) dynamically map the regulatory events that lead to asymmetry. Our innovation is to study a mycobacterial-specific protein that creates heterogeneity in a genetically identical population. We will do so by leveraging our expertise in advanced imaging techniques in combination with more traditional methods. Successful completion of these aims will lead to hypotheses about the function of LamA that can be tested with molecular and biochemical approaches. Further, our results will advance our understanding of the molecular basis of cell-division mediated heterogeneity, which has far- reaching consequences for the treatment of TB. For example, identifying the molecular mechanism(s) that leads to subpopulations of bacteria better able to survive antibiotic therapy will allow us to design drug strategies that target heterogeneity. Such interventions could treat TB more quickly, something that would greatly help reduce the global burden of TB disease.