The siderophore system is essential for viability of Aspergillus nidulans:: functional analysis of two genes encoding L-ornithine N5-monooxygenase (sidA) and a non-ribosomal peptide synthetase (sidC)
The siderophore system is essential for viability of Aspergillus nidulans:: functional analysis of two genes encoding L-ornithine N5-monooxygenase (sidA) and a non-ribosomal peptide synthetase (sidC)
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DOI：
10.1046/j.1365-2958.2003.03586.x
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发表时间：
2003-07-01
影响因子：
3.6
通讯作者：
Haas, H
中科院分区：
文献类型：
--
作者：
Eisendle, M;Oberegger, H;Haas, H
丝状子囊菌A. nidulans产生两种主要的铁载体：它分泌三乙酰fusarinine C以捕获铁，并在细胞内含有ferricrocin。在这项研究中，我们报告了两个铁载体生物合成基因的特征，分别编码L-鸟氨酸N-5-单加氧酶和编码非核糖体肽合成酶的CITRA C。破坏cDNAC消除了铁微菌素的合成，缺失cDNAA完全阻断了铁载体的生物合成。铁载体缺乏的菌株不能生长，除非生长培养基中添加铁载体，这表明铁载体系统是A.在铁耗尽和铁充满的条件下，nidulans。铁载体缺陷突变体的生长部分恢复高浓度的Fe 2+（而不是Fe 3+）表明存在一个额外的亚铁运输系统和缺乏一个有效的还原铁assmilatory系统。摄取研究表明，F结合铁被转移到细胞铁微素，而铁微素在摄取后被储存。铁载体缺陷突变体能够从三乙酰镰孢菌素C合成铁微菌素。铁微霉素缺乏导致细胞内实验室铁池增加，抗氧化酶上调和对氧化还原循环剂百草枯敏感性升高。这表明缺乏这种细胞铁储存化合物会导致氧化应激。此外，ferricrocin的生物合成被发现是至关重要的有效分生孢子。
The filamentous ascomycete A. nidulans produces two major siderophores: it excretes triacetylfusarinine C to capture iron and contains ferricrocin intracellularly. In this study we report the characterization of two siderophore biosynthetic genes, sidA encoding L-ornithine N-5-monooxygenase and sidC encoding a non-ribosomal peptide synthetase respectively. Disruption of sidC eliminated synthesis of ferricrocin and deletion of sidA completely blocked siderophore biosynthesis. Siderophore-deficient strains were unable to grow, unless the growth medium was supplemented with siderophores, suggesting that the siderophore system is the major iron assimilatory system of A. nidulans during both iron depleted an iron-replete conditions. Partial restoration of the growth of siderophore-deficient mutants by high concentrations of Fe2+ (but not Fe3+) indicates the presence of an additional ferrous transport system and the absence of an efficient reductive iron assmilatory system. Uptake studies demonstrated that F bound iron is transferred to cellular ferricrocin whereas ferricrocin is stored after uptake. The siderophore-deficient mutant was able to synthesize ferricrocin from triacetylfusarinine C. Ferricrocin-deficiency caused an increased intracellular lab le iron pool, upregulation of antioxidative enzymes and elevated sensitivity to the redox cycler paraquat. This indicates that the lack of this cellular iron storage compound causes oxidative stress. Moreover, ferricrocin biosynthesis was found to be crucial for efficient conidiation.