The role of arginine catabolic pathways in modulating staphylococcal fitness

摘要 尽管临床护理取得了数十年的进步，葡萄球菌感染的高发病率仍然是一个主要的问题， 公共卫生问题。多重耐药金黄色葡萄球菌分离株和凝固酶阴性 表皮葡萄球菌经常在医院环境中分离，并显著限制了治疗性感染。 选项.事实上，越来越明显的是，对葡萄球菌生物学的基本理解 并且影响其适合性的因素是开发有效治疗剂所必需的。为了实现这一目标，我们 最近发现精氨酸分解代谢酶包括一氧化氮的重要生理功能 合成酶（NOS）和精氨酸脱亚胺酶（ADI）在促进生长和控制程序性细胞死亡（PCD）中的作用 在葡萄球菌中。在正常生理条件下，NOS活性通过激活呼吸作用促进生长 以及预防代谢功能障碍，包括多糖细胞内粘附素的过度产生， （PIA）.然而，在酸性条件下，乙酸盐（葡萄糖代谢的副产物）流入细胞质 破坏NOS的正常功能，促进NOS依赖性活性氧的产生 (ROS)和PCD。有趣的是，通过ADI途径的碳通量似乎对抗NOS依赖的PCD。 这些途径影响葡萄球菌生理学的机制仍在深入研究中 并构成本申请的主题。在目标1中，我们将测试NOS如何通过抑制 PIA生产作为其正常生理活动的一部分。此外，我们将研究苯丙氨酸是否在 在NOS依赖性PIA抑制中的作用以及NOS活性是否影响PIA的致病潜力 使用中枢神经系统（CNS）导管感染的幼年小鼠模型，对金黄色葡萄球菌进行培养。在目标#2中，我们 将检验一氧化氮合酶依赖的活性氧产生的假设，在PCD的结果从NOS解偶联， 其中NOS产生超氧化物而不是一氧化氮作为副产物的现象。最后，在目标#3中，我们将 测试精氨酸脱亚胺酶和精氨酸脱亚胺酶途径通过激活过氧化氢酶对抗PCD的潜力 通过谷氨酸生物合成的活性。通过这些研究，我们将获得更深层次的机理 了解各种精氨酸分解代谢途径如何影响葡萄球菌的生理和适应性。

ABSTRACT Despite decades of advances in clinical care, the high incidence of staphylococcal infections remain a major public health concern. Multiple antibiotic-resistant isolates of Staphylococcus aureus and coagulase-negative Staphylococcus epidermidis are frequently isolated in the hospital environment and significantly limit therapeutic options. Indeed, it is increasingly becoming evident that a fundamental understanding of staphylococcal biology and factors affecting its fitness are required for the development of effective therapeutics. Towards this goal, we have recently identified important physiological functions for arginine catabolic enzymes including nitric oxide synthase (NOS) and arginine deiminase (ADI), in promoting growth and controlling programmed cell death (PCD) in staphylococci. Under normal physiological conditions, NOS activity promotes growth by activating respiration and preventing metabolic dysfunction including excessive production of the polysaccharide intracellular adhesin (PIA). However, influx of acetate (a byproduct of glucose metabolism) into the cytoplasm under acidic conditions appears to corrupt normal function of NOS and promotes NOS-dependent production of reactive oxygen species (ROS) and PCD. Interestingly, carbon flux through the ADI pathway appears to counter NOS-dependent PCD. The mechanism by which these pathways affect staphylococcal physiology is still under intense investigation and constitutes the subject of this application. In Aim #1, we will test how NOS promotes growth by suppressing PIA production as part of its normal physiological activity. Further, we will investigate if phenylalanine plays a role in NOS-dependent PIA suppression and whether NOS activity affects the pathogenic potential of staphylococci using an infant mouse model of central nervous system (CNS) catheter infection. In Aim #2, we will test the hypothesis that NOS-dependent ROS production during PCD results from NOS uncoupling, a phenomenon wherein NOS generates superoxide rather than nitric oxide as byproduct. Finally in Aim #3, we will test the potential for the arginine deiminase and the arginase pathways in countering PCD by activating catalase activity through glutamate biosynthesis. On completion of these studies, we will gain a deeper mechanistic understanding of how various arginine catabolic pathways affect staphylococcal physiology and fitness.