Métaux et Microorganismes, Chimie, Biologie et Applications, FRE 3211, CNRS-Université de Strasbourg, ESBS, Blvd Sébastien Brant, BP 10412, 67413, Strasbourg, Illkirch, France.
Amino Acids. 2010 May;38(5):1447-59. doi: 10.1007/s00726-009-0358-0. Epub 2009 Sep 29.
Pyoverdines, the main siderophores produced by fluorescent Pseudomonads, comprise a fluorescent dihydroxyquinoline chromophore attached to a strain-specific peptide. These molecules are thought to be synthesized as non-fluorescent precursor peptides that are then modified to give functional pyoverdines. Using the fluorescent properties of PVDI, the pyoverdine produced by Pseudomonas aeruginosa PAO1, we were able to show that PVDI was not present in the cytoplasm of the bacteria, but large amounts of a fluorescent PVDI precursor PVDIp were stored in the periplasm. Like PVDI, PVDIp is able to transport iron into P. aeruginosa cells. Mutation of genes encoding the periplasmic PvdN, PvdO and PvdP proteins prevented accumulation of PVDIp in the periplasm and secretion of PVDI into the growth medium, indicating that these three enzymes are involved in PVDI synthesis. Mutation of the gene encoding PvdQ resulted in the presence of fluorescent PVDI precursor in the periplasm and secretion of a functional fluorescent siderophore that had different isoelectric properties to PVDI, suggesting a role for PvdQ in the periplasmic maturation of PVDI. Mutation of the gene encoding the export ABC transporter PvdE prevented PVDI production and accumulation of PVDIp in the periplasm. These data are consistent with a model in which a PVDI precursor peptide is synthesized in the cytoplasm and exported to the periplasm by PvdE where siderophore maturation, including formation of the chromophore moiety, occurs in a process involving the PvdN, PvdO, PvdP and PvdQ proteins.
绿脓菌素是荧光假单胞菌产生的主要铁载体，由连接到菌株特异性肽的荧光二羟基喹啉发色团组成。这些分子被认为是作为非荧光前体肽合成的，然后修饰以赋予功能性绿脓菌素。利用 PVDI 的荧光特性，即荧光假单胞菌 PAO1 产生的绿脓菌素，我们能够表明 PVDI 不存在于细菌的细胞质中，而是大量储存在周质中的荧光 PVDI 前体 PVDIp。与 PVDI 一样，PVDIp 能够将铁运入假单胞菌细胞。编码周质 PvdN、PvdO 和 PvdP 蛋白的基因的突变阻止了 PVDIp 在周质中的积累和 PVDI 分泌到生长培养基中，表明这三种酶参与 PVDI 的合成。编码 PvdQ 蛋白的基因的突变导致荧光 PVDI 前体存在于周质中，并分泌出一种具有与 PVDI 不同等电特性的功能性荧光铁载体，表明 PvdQ 在 PVDI 的周质成熟中起作用。编码出口 ABC 转运蛋白 PvdE 的基因的突变阻止了 PVDI 的产生和 PVDIp 在周质中的积累。这些数据与以下模型一致：即 PVDI 前体肽在细胞质中合成，并由 PvdE 输出到周质，在 PvdN、PvdO、PvdP 和 PvdQ 蛋白参与的过程中，铁载体成熟包括发色团部分的形成。
