Phosphate homeostasis and uptake in Staphylococcus aureus

项目总结/摘要 磷酸盐是一种必需的营养素，对细胞生理学的各个方面都有贡献。尽管其重要性， 磷酸盐也可能是有毒，因此磷酸盐摄取和体内平衡的调节对于所有形式的生命都是至关重要的。 这一点可以通过观察到破坏这些过程可以降低许多病毒的毒性来证明。 肠细菌病原体。金黄色葡萄球菌（Staphylococcus aureus）是一种严重危害人类健康的病原菌 由于抗生素耐药性的持续出现，健康受到威胁。令人惊讶的是，无论是磷酸盐摄取还是 对S.金黄色。尽管磷酸盐稳态 in S.金黄色葡萄球菌与达托霉素耐药性的变化有关。磷酸盐的体内平衡 在大肠杆菌中进行了全面的研究，在大肠杆菌中，它由称为PhoBR的双组分系统控制 （PhoPR在S. aureus)具有良好的抗菌活性。在大肠在大肠杆菌中，PhoBR的活性受PstSCAB磷酸转运蛋白的调控， PhoU辅助蛋白。PstSCAB或PhoU在E.大肠杆菌和其他细菌导致组成型 PhoBR活化。初步调查表明，S.金黄色葡萄球菌具有三磷酸盐 转运蛋白PstSCAB、PitA和NptA，它们扩展了S.金黄色葡萄球菌可获得磷酸盐 并有助于感染。In S.金黄色葡萄球菌，PstSCAB和NptA，但不包括PitA，依赖于PhoPR 表情进一步不同于E. coli、S.金黄色葡萄球菌有三个PhoU同源物，每个与一个 传送器。令人惊讶的是，PstSCAB或标准PhoU同系物的缺失并不导致组成型的 PhoPR在S.金黄色。这些和其他观察结果表明，磷酸盐稳态在S。 金黄色葡萄球菌不同于已建立的模型。PhoPR或PstSCAB和NptA的缺失降低了S.金黄色 以引起感染。有趣的是，phoPR和pstSCAB nptA突变体彼此之间并没有表型复制。的 phoPR突变体在磷酸盐限制性环境中的生长能力降低，导致感染的能力相对于 转运蛋白双突变体。这些观察结果表明PhoPR调节其他未知的 非转运蛋白依赖性因子，使S.金黄色葡萄球菌在磷酸盐限制下存活并引起疾病。 总之，这些观察结果导致了一个假说，即一个扩展的调节蛋白控制着 S.金黄色葡萄球菌，而这种调节网络破坏减少了葡萄球菌 毒性。本提案的两个目的将检验这一假设，并阐明PhoPR控制的因素 使S.金黄色葡萄球菌引起感染。目的I将确定PhoPR对S的贡献。金黄色磷酸盐 体内平衡和毒性。目的II将评估S. 金黄色葡萄球菌控制磷酸盐稳态。

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.