4′-Phosphopantetheinyl transferase-encoding npgA is essential for siderophore biosynthesis in Aspergillus nidulans
4′-Phosphopantetheinyl transferase-encoding npgA is essential for siderophore biosynthesis in Aspergillus nidulans
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DOI：
10.1007/s00294-003-0434-z
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发表时间：
2003-12-01
期刊：
影响因子：
2.5
通讯作者：
Haas, H
中科院分区：
文献类型：
--
作者：
Oberegger, H;Eisendle, M;Haas, H
构巢曲霉产生两种主要的铁载体：它分泌三乙酰镰孢菌素C来捕获铁，并含有铁微菌素作为细胞内的铁储存化合物。铁载体生物合成涉及非核糖体肽合成酶（NRPS）的酶活性。NRPS含有4 '-磷酸泛酰巯基乙胺作为必需的辅基，其通过4'-磷酸泛酰巯基乙胺基转移酶连接。A. nidulans似乎具有至少一个编码这种酶的基因npgA。使用携带温度敏感等位基因cfwA 2的菌株，我们表明NpgA对于含肽键的铁微菌素和含酯键的三乙酰fusarinene C的生物合成都是必需的。cfwA 2菌株被发现是铁饥饿的限制性温度在充满铁的条件下，与铁载体系统是主要的铁吸收系统，我们最近证明。北方分析表明，与其他参与铁载体生物合成和摄取的基因相反，npgA的表达不受GATA转录因子SreA控制。先前已表明，NpgA是通过α-氨基己二酸途径生物合成青霉素、色素和潜在赖氨酸所必需的。补充赖氨酸加三乙酰fusarinine C恢复正常生长的cfwA 2菌株在限制性温度，这表明生长缺陷的突变体主要是由于铁载体和赖氨酸的生物合成受损。
Aspergillus nidulans produces two major siderophores: it excretes triacetylfusarinine C to capture iron and contains ferricrocin as an intracellular iron-storage compound. Siderophore biosynthesis involves the enzymatic activity of nonribosomal peptide synthetases (NRPS). NRPS contain 4'-phosphopantetheine as an essential prosthetic group, which is attached by 4'-phosphopantetheinyl transferases. A. nidulans appears to possess at least one gene, npgA, encoding such an enzyme. Using a strain carrying a temperature-sensitive allele, cfwA2, we showed that NpgA is essential for biosynthesis of both the peptide bond-containing ferricrocin and the ester bond-containing triacetylfusarinene C. The cfwA2 strain was found to be iron-starved at the restrictive temperature during iron-replete conditions, consistent with the siderophore system being the major iron-uptake system-as we recently demonstrated. Northern analysis indicated that, in contrast to other genes which are involved in siderophore biosynthesis and uptake, expression of npgA is not controlled by the GATA-transcription factor SreA. It was shown previously that NpgA is required for biosynthesis of penicillin, pigment, and potentially lysine via the alpha-aminoadipate pathway. Supplementation with lysine plus triacetylfusarinine C restored normal growth of the cfwA2 strain at the restrictive temperature, suggesting that the growth defect of the mutant is mainly due to impaired biosynthesis of siderophores and lysine.