Phosphate homeostasis and uptake in Staphylococcus aureus

项目摘要/摘要 磷酸盐是一种基本的营养物质，对细胞生理的各个方面都有贡献。尽管它很重要， 磷酸盐也可能是有毒的，因此调节磷酸盐的吸收和动态平衡对所有形式的生命都是至关重要的。 这一点的例证是，观察到扰乱这些过程会降低许多 肠道细菌病原体。金黄色葡萄球菌是一种对人类构成严重威胁的毁灭性病原体。 由于持续出现抗生素耐药性而导致的健康问题。令人惊讶的是，无论是磷酸盐吸收还是 金黄色葡萄球菌的动态平衡已经得到了系统的研究。这是尽管磷酸盐的动态平衡 在金黄色葡萄球菌中，与达托霉素耐药性的变化有关。磷酸盐动态平衡一直是最 在大肠杆菌中进行了全面的研究，在那里它由一种名为PhoBR的双组分系统控制 (PhoPR in S.aureus)。在大肠杆菌中，PhoBR的活性由PstSCAB磷酸盐转运体和 Phou辅助蛋白。在大肠杆菌和其他细菌中失去PstSCAB或Phou会导致构成 激活PhoBR。初步调查显示，金黄色葡萄球菌具有三种磷酸盐 转运蛋白PstSCAB、PitA和NPTA，它们扩大了金黄色葡萄球菌获得磷酸盐的环境 并导致感染。在金黄色葡萄球菌中，PstSCAB和NPTA，而不是PITA，都依赖于PhoPR 表情。与大肠杆菌进一步不同的是，金黄色葡萄球菌有三个Phou同源物，每个都有一个 传送器。令人惊讶的是，PstSCAB或规范Phou同源基因的丢失并不会导致结构性 金黄色葡萄球菌中PhoPR的激活。这些和其他观察结果表明，在S。 金星与已建立的模型不同。PhoPR或PstSCAB和NPTA的丢失降低金黄色葡萄球菌的能力 以引起感染。有趣的是，PhoPR和pstSCABNPTA突变体之间不存在表型复制。这个 PhoPR突变体在磷酸盐受限的环境中生长的能力降低，并导致感染 传送器双重变种人。这些观察表明，PhoPR调节额外的未知 使金黄色葡萄球菌在磷酸盐限制下存活并致病的非转运体因子。 总而言之，这些观察结果导致了一种假设，即调控蛋白的扩展谱系控制着 金黄色葡萄球菌中磷酸盐稳态和该调控网络的破坏减少了葡萄球菌 致命性。这项提议的两个目的将检验这一假说并阐明由PhoPR控制的因素 使金黄色葡萄球菌能够引起感染。目的确定PhoPR对金黄色葡萄球菌的作用。 动态平衡和毒性。目的II将评估S。 控制磷酸盐的动态平衡。

Project Summary / Abstract Phosphate is an essential nutrient that contributes to all aspects of cellular physiology. Despite its essentiality, phosphate can also be toxic, thus regulation of phosphate uptake and homeostasis is critical for all forms of life. This is exemplified by the observation that disrupting these processes reduces the virulence of many enterobacterial pathogens. Staphylococcus aureus is a devastating pathogen that is a serious threat to human health due to the continued emergence of antibiotic resistance. Surprisingly, neither phosphate uptake nor homeostasis have been systematically studied in S. aureus. This is despite the fact that phosphate homeostasis in S. aureus is linked to changes in daptomycin resistance. Phosphate homeostasis has been most comprehensively studied in Escherichia coli where it is controlled by a two-component system known as PhoBR (PhoPR in S. aureus). In E. coli, the activity of PhoBR is controlled by the PstSCAB phosphate transporter and the PhoU accessory protein. Loss of either PstSCAB or PhoU in E. coli and other bacteria results in constitutive activation of PhoBR. Preliminary investigations have revealed that S. aureus possesses three phosphate transporters, PstSCAB, PitA, and NptA, that expand the environments where S. aureus can obtain phosphate and contribute to infection. In S. aureus, both PstSCAB and NptA, but not PitA, are dependent on PhoPR for expression. Further differing from E. coli, S. aureus possesses three PhoU homologs, one associated with each transporter. Surprisingly, loss of either PstSCAB or the canonical PhoU homolog does not result in constitutive activation of PhoPR in S. aureus. These and other observations demonstrate that phosphate homeostasis in S. aureus differs from established models. Loss of PhoPR or PstSCAB and NptA reduces the ability of S. aureus to cause infection. Intriguingly, the phoPR and pstSCABnptA mutants do not phenocopy each other. The phoPR mutant has a reduced ability to grow in phosphate-limited environments and cause infection relative to the transporter double mutant. These observations indicate that PhoPR regulates additional unknown transporter-independent factors that enable S. aureus to survive phosphate limitation and cause disease. Together, these observations lead to the hypothesis that an expanded repertoire of regulatory proteins controls phosphate homeostasis in S. aureus and that disruption of this regulatory network reduces staphylococcal virulence. The two Aims of this proposal will test this hypothesis and elucidate the factors controlled by PhoPR that enable S. aureus to cause infection. Aim I will determine the contribution of PhoPR to S. aureus phosphate homeostasis and virulence. Aim II will evaluate the contribution of the three PhoU homologs possessed by S. aureus to controlling phosphate homeostasis.