Isolation, Structure Elucidation, and Biosynthesis of an Unusual Hydroxamic Acid Ester-Containing Siderophore from Actinosynnema mirum
Isolation, Structure Elucidation, and Biosynthesis of an Unusual Hydroxamic Acid Ester-Containing Siderophore from Actinosynnema mirum
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DOI：
10.1021/np300046k
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发表时间：
2012-05-01
影响因子：
5.1
通讯作者：
Marahiel, Mohamed A.
中科院分区：
文献类型：
--
作者：
Giessen, Tobias W.;Franke, Kamila B.;Marahiel, Mohamed A.
在这项研究中，我们报道了mirubactin(1)的分离、结构解析和生物合成，mirubactin是一种铁载体，在天然产物中具有前所未有的化学功能，即o -酰基羟肟酸酯。Mirubactin是第一个从放线菌属（Actinosynnema）中分离到的铁蛋白，也是第一个可以确定生物合成基因簇的天然产物。通过波谱（NMR， IR和UV/vis）和质谱方法的结合进行了结构解析，发现在- n -甲酰基- - n -羟基鸟氨酸的- n -羟基和2,3-二羟基苯甲酸酯部分之间存在一个不寻常的酯键。A. mirum基因组的生物信息学分析和随后假定的生物合成机制的生化表征确定了负责mirubactin组装的基因簇。提出的mirubactin的生物合成包括独立载体蛋白结合底物的迭代使用，以及由c端缩合结构域催化的酯键形成步骤，从而揭示了一个有趣的系统，可用于进一步的生化研究，以更深入地了解非核糖体肽合成酶催化的铁载体生物合成。
In this study we report the isolation, structure elucidation, and biosynthesis of mirubactin (1), a siderophore containing an unprecedented chemical functionality in natural products, namely, an O-acyl hydroxamic acid ester. Mirubactin represents the first siderophore isolated from the genus Actinosynnema and the first natural product produced by Actinosynnema mirum whose biosynthetic gene cluster could be identified. Structure elucidation was accomplished through a combination of spectroscopic (NMR, IR, and UV/vis) and mass spectrometric methods and revealed the presence of an unusual ester bond between the delta-N-hydroxyl group of delta-N-formyl-delta-N-hydroxyornithine and a 2,3-dihydroxybenzoate moiety. Bioinformatic analysis of the A. mirum genome and subsequent biochemical characterization of the putative biosynthetic machinery identified the gene cluster responsible for mirubactin assembly. The proposed biosynthesis of mirubactin comprises the iterative use of a stand-alone carrier-protein-bound substrate, as well as an ester-bond-forming step catalyzed by a C-terminal condensation domain, thus revealing an interesting system for further biochemical studies to gain a deeper understanding of nonribosomal peptide synthetase-catalyzed siderophore biosynthesis.