The Role of the Cytoplasmic Heme-binding Protein (PhuS) of Pseudomonas aeruginosa in Intracellular Heme Trafficking and Iron Homeostasis
The Role of the Cytoplasmic Heme-binding Protein (PhuS) of Pseudomonas aeruginosa in Intracellular Heme Trafficking and Iron Homeostasis
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DOI：
10.1074/jbc.m806068200
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发表时间：
2009-01-02
影响因子：
4.8
通讯作者：
Wilks, Angela
中科院分区：
文献类型：
--
作者：
Kaur, Ajinder P.;Lansky, Ila B.;Wilks, Angela
细胞质血红素结合蛋白GHOS，在毛皮调节的假单胞菌血红素利用（phu）操纵子内编码，先前已被证明可以将血红素运输到铁调节的血红素加氧酶（HO）。我们进一步研究了在铜绿假单胞菌铁载体缺陷和野生型背景下，phuS和hemO基因被破坏后，phuS在血红素转运至HO中的作用。以前的研究表明，删除血红素O会阻止细胞利用血红素作为铁的唯一来源。然而，单独破坏phuS导致生长缓慢的表型，与其作为血红素转运蛋白HO的作用一致。此外，与hemO和hemO/phuS缺失菌株相反，phuS敲除在血红素的存在下过早地产生绿脓菌素。在野生型菌株中的FurS蛋白水平的蛋白质印迹分析表明，毛皮调节的phu操纵子可以在血红素的存在下去阻遏。此外，绿脓菌素生产的过早发生需要血红素和功能HO。抑制的表型增加外部血红素浓度表明，减少血红素通量通过HO的结果在过早生产绿脓菌素。绿脓菌素的过早产生不是由于降低细胞内铁水平，作为减少血红素通量通过HO的结果。然而，phuS突变体的转录分析表明，细胞正在感知铁剥夺。目前的数据表明，BRAS具有双重功能，在运输血红素HO，并在直接或间接的传感和维持铁和血红素的稳态。
The cytoplasmic heme-binding protein PhuS, encoded within the Fur-regulated Pseudomonas heme utilization (phu) operon, has previously been shown to traffic heme to the iron-regulated heme oxygenase (HO). We further investigate the role of PhuS in heme trafficking to HO on disruption of the phuS and hemO genes in a Pseudomonas aeruginosa siderophore-deficient and wild-type background. Previous studies have shown that deletion of hemO prevents the cells from utilizing heme as the sole source of iron. However, disruption of phuS alone resulted in a slow growth phenotype, consistent with its role as a heme-trafficking protein to HO. Furthermore, in contrast to the hemO and hemO/phuS deletion strains, the phuS knockout prematurely produced pyocyanin in the presence of heme. Western blot analysis of PhuS protein levels in the wild-type strain showed that Fur-regulation of the phu operon could be derepressed in the presence of heme. In addition the premature onset of pyocyanin production requires both heme and a functional HO. Suppression of the phenotype on increasing the external heme concentration suggested that the decreased heme-flux through HO results in premature production of pyocyanin. The premature production of pyocyanin was not due to lower intracellular iron levels as a result of decreased heme flux through HO. However, transcriptional analysis of the phuS mutants indicates that the cells are sensing iron deprivation. The present data suggest that PhuS has a dual function in trafficking heme to HO, and in directly or indirectly sensing and maintaining iron and heme homeostasis.