Novel mechanisms of DNA repair and cell cycle regulation in bacteria

项目总结： 当今医学中的一个主要问题是抗药性细菌的出现和持续存在。虽然 细菌已经进化出几种在恶劣环境中生长的策略，许多细菌物种广泛地应对 在不利的条件下，通过调节生长和诱导DNA损伤反应。事实上，所有的 生物体通过征募DNA修复途径和调节细胞周期进程来应对DNA损伤。 细菌细胞不断地暴露在由细胞内来源引起的广泛的DNA损伤中， 环境应激源、抗生素治疗和消毒剂在医院环境中的应用。虽然DNA 修复和细胞周期检查点已经在一些细菌中得到了很好的研究，但对它们的了解要少得多。 革兰氏阳性细菌的过程。一个主要的挑战是，即使是研究最充分的革兰氏阳性菌 细菌，枯草杆菌，基因组中几乎一半的基因具有未知的功能，代表着一种 在我们对这些细菌如何缓解影响生长和发育的压力的理解上存在关键和根本的差距 扩散。虽然枯草芽孢杆菌不会引起疾病，但它与许多重要的 人类病原体，包括耐甲氧西林金黄色葡萄球菌、单核细胞增多性李斯特菌和几种 其他导致许多医院获得性感染的病原体，这些感染给经济造成了巨大的影响 每年给我们的医疗系统带来的负担。因此，重要的是要了解一个广泛的群体如何 临床上相关细菌对DNA损伤作出反应并调节细胞增殖。这样做的长期目标是 研究是为了了解未研究的基因和新机制对DNA修复和细胞的贡献 革兰氏阳性菌的循环调节。我们使用大规模全基因组方法确定了几个 在革兰氏阳性细菌中高度保守并对DNA修复和 对细胞增殖的调控。其中两种基因产物定义了一种新的DNA切除修复途径，而 另外四个基因对DNA损伤检查点恢复至关重要，使细胞在 损坏已被修复。我们扩展了这些实验，以继续识别与 控制启动时机和细胞增殖的调控伙伴。我们预计这些研究将导致 参与启动、DNA修复和细胞周期检查点的蛋白质的完整机械特征。 我们计划研究的所有基因要么是必需的，要么当受损时会导致严重的生长缺陷， 强调它们作为新的抗微生物疗法的可能靶标的重要性。

Project Summary: A major problem in medicine today is the emergence and persistence of antibiotic resistant bacteria. Although bacteria have evolved several strategies to grow in harsh environments, many bacterial species broadly cope in unfavorable conditions by regulating growth and through inducing DNA damage responses. In fact, all organisms respond to DNA damage by enlisting DNA repair pathways and by regulating cell cycle progression. Bacterial cells are constantly exposed to a broad spectrum of DNA damage caused by intracellular sources, environmental stressors, antibiotic treatments, and disinfectants applied in hospital settings. Although DNA repair and cell cycle checkpoints have been well studied in some bacteria, far less is known about these processes in Gram-positive bacteria. One major challenge is that even for the most well studied Gram-positive bacterium, Bacillus subtilis, almost half of the genes in the genome are of unknown function, representing a critical and fundamental gap in our understanding of how these bacteria mitigate stress that affects growth and proliferation. While Bacillus subtilis does not cause disease, it is closely related to a number of important human pathogens, including Methicillin-resistant Staphylococcus aureus, Listeria monocytogenes and several other pathogens that are responsible for many hospital-acquired infections, which impose significant economic burdens on our healthcare system annually. Therefore, it is important to understand how a broad group of clinically relevant bacteria respond to DNA damage and regulate cell proliferation. The long-term goal of this research is to understand the contribution of unstudied genes and novel mechanisms to DNA repair and cell cycle regulation in Gram-positive bacteria. We used large-scale genome-wide approaches to identify several uncharacterized genes that are highly conserved among Gram-positive bacteria and critical for DNA repair and regulation of cell proliferation. Two of these gene products define a new DNA excision repair pathway while four other genes are critical for DNA damage checkpoint recovery, allowing cells to re-enter the cell cycle after the damage has been repaired. We expand these experiments to continue to identify novel interactions with regulatory partners that control initiation timing and cell proliferation. We expect these studies will result in the complete mechanistic characterization of proteins involved in initiation, DNA repair, and cell cycle checkpoints. All of the genes we propose to study are either essential or cause severe growth defects when impaired, underscoring their importance as possible targets for novel antimicrobial therapies.