Iron-mediated regulation of alkaline proteinase production in Pseudomonas aeruginosa
Iron-mediated regulation of alkaline proteinase production in Pseudomonas aeruginosa
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DOI：
10.1111/j.1348-0421.2001.tb01289.x
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发表时间：
2001-01-01
影响因子：
2.6
通讯作者：
Okuda, K
中科院分区：
文献类型：
--
作者：
Shigematsu, T;Fukushima, J;Okuda, K
我们分析了铁对铜绿假单胞菌碱性蛋白酶（AP）产生的调节。通过基于抗体的测定系统检测从对数中期到稳定期的细胞外 AP 产生，并受到培养基中铁的强烈抑制。 Northern 杂交和引物延伸表明这种抑制发生在转录水平。引物延伸分析表明AP基因的转录起始点位于距翻译起始点-84位的核苷酸位置。此外，我们研究了这种转录抑制是否涉及 PvdS 蛋白。使用pvdS突变株，替代cr因子基因揭示PvdS蛋白是AP完全表达所必需的，并且先前的研究表明pvdS的表达也受到铁的抑制。因此，我们认为抑制 AP 产生的一种机制是通过降低 PvdS 蛋白水平来发挥作用。纯化的 AP 分解转铁蛋白，并从中释放铁。将纯化的 AP 添加到含有转铁蛋白作为唯一铁源的培养基中可增强铜绿假单胞菌的生长。此外，AP基因的突变降低了含有转铁蛋白作为唯一铁源的培养基中的生长速率。这些结果清楚地表明 AP 表达应该发生在游离铁缺乏的环境中，并强调了 AP 对感染部位铁获取的重要性。
We analyzed the regulation by iron of alkaline proteinase (AP) production in Pseudomonas aeruginosa. Extracellular AP production was detected from the mid-logarithmic to the stationary phase by an antibody-based assay system, and was strongly repressed by iron in the medium. This repression was shown by Northern hybridization and primer extension to occur at the level of transcription. The primer extension analysis revealed that the start point of transcription of AP gene was the nucleotide position -84 from the start point of translation. Furthermore, we investigated whether this transcriptional repression involved PvdS protein. Using the mutant strain of pvdS, the alternative cr factor gene revealed that the PvdS protein is required for the full expression of AP, and a previous study showed that expression of pvdS is also repressed by iron. Therefore, we thought that one mechanism of repression of AP production operated through reduction of the PvdS protein level. Purified AP decomposed the transferrin, and released iron from it. Purified AP added to the medium containing transferrin as the only iron source enhanced the growth of R aeruginosa. Moreover, mutation in the AP gene decreased the growth rate in the medium containing the transferrin as the only iron source. These results clearly indicated that AP expression should occur in a free-iron-deficient environment and emphasized the importance of AP to iron acquisition in the infection site.