Novel mechanisms of DNA repair and cell cycle regulation in bacteria

项目摘要： 当今医学的一个主要问题是抗生素耐药细菌的出现和持续存在。虽然 细菌已经进化出几种策略来在恶劣的环境中生长，许多细菌物种广泛地科普 在不利的条件下，通过调节生长和诱导DNA损伤反应。其实所有 生物体通过启动DNA修复途径和调节细胞周期进程对DNA损伤作出反应。 细菌细胞不断暴露于由细胞内来源引起的广谱DNA损伤， 环境压力、抗生素治疗和医院环境中使用的消毒剂。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，但对这些知之甚少。 革兰氏阳性菌中的突起。一个主要的挑战是，即使是研究最充分的革兰氏阳性， 对于枯草杆菌，基因组中几乎一半的基因功能未知，代表了一种 我们对这些细菌如何缓解影响生长的压力的理解存在着关键和根本的差距， 增殖虽然枯草芽孢杆菌不引起疾病，但它与许多重要的微生物密切相关。 人类病原体，包括耐甲氧西林金黄色葡萄球菌、单核细胞增生李斯特菌和几种 其他病原体是许多医院获得性感染的原因，这对医院感染造成了重大的经济损失。 每年都给我们的医疗系统带来负担。因此，重要的是要了解一个广泛的群体如何 临床相关细菌响应DNA损伤并调节细胞增殖。长期目标是 研究的目的是了解未研究的基因和新机制对DNA修复和细胞凋亡的贡献。 革兰氏阳性菌的周期调节。我们使用大规模的全基因组方法来识别几个 在革兰氏阳性菌中高度保守且对DNA修复至关重要的未表征基因， 调节细胞增殖。其中两种基因产物定义了一种新的DNA切除修复途径， 另外四个基因对DNA损伤检查点的恢复至关重要，允许细胞在损伤后重新进入细胞周期。 损坏的地方已经修好了。我们扩大这些实验，继续确定新的相互作用， 控制起始时间和细胞增殖的调节伙伴。我们预计这些研究将导致 完整的机制表征蛋白质参与启动，DNA修复，和细胞周期检查点。 我们打算研究的所有基因要么是必不可少的，要么在受损时会导致严重的生长缺陷， 强调了它们作为新型抗微生物疗法的可能靶点的重要性。

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.