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

摘要 结核病（TB），一种由结核分枝杆菌（Mtb）引起的细菌感染，现在是主要原因 一种传染源造成的死亡其中一个原因是Mtb细胞的亚群甚至可以存活， 漫长的化疗，阻止疾病的治愈。这些存活的细胞具有表型耐受性，但 对抗生素治疗有遗传抗性。因此，基因相同的细菌表现出不同的 表型是治疗TB的重大障碍。更好地理解分子 这一现象背后的机制可能导致结核病和其他分枝杆菌的治疗进展， 感染.大部分异质性开始于分枝杆菌细胞分裂。每次分枝杆菌 分裂会产生具有不同特征的女儿。我们最近发现这个过程 基因编码删除一个基因，我们命名为lamA，导致细胞生长和分裂 更对称，对某些抗生素的敏感性更一致。LamA的功能以及它如何 介导的不对称生长和分裂是未知的。在这里，我们建议研究分子 LamA的功能。我们发表的和初步的数据表明，LamA定位于分裂的网站，在那里它 抑制了新增长极的成熟。此外，我们已经将LamA与磷酸化 一种必需的肽聚糖合酶的状态，并已发现其自身的定位受 磷酸化这导致了我们的假设，即LamA动态地中断了未知的通信 在完成分裂和延伸的多蛋白复合物之间的中继，在磷酸化中， 依赖的方式。为了验证该模型，我们提出了以下目标：（1）定义通信中继 之间的分裂和延伸复合物;和，（2）动态映射的调节事件，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， 基因相同的人群。我们将利用我们在先进成像技术方面的专业知识， 与更传统的方法相结合。这些目标的成功完成将导致以下假设： LamA的功能可以用分子和生物化学方法进行测试。此外，我们的结果将 推进我们对细胞分裂介导的异质性的分子基础的理解，这已经远远- 对结核病的治疗产生影响。例如，确定分子机制， 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。这些干预措施可以更快地治疗结核病， 大大有助于减轻结核病的全球负担。

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.