Structure and biosynthesis of heat-stable antifungal factor (HSAF), a broad-spectrum antimycotic with a novel mode of action
Structure and biosynthesis of heat-stable antifungal factor (HSAF), a broad-spectrum antimycotic with a novel mode of action
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DOI：
10.1128/aac.00931-06
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发表时间：
2007-01-01
影响因子：
4.9
通讯作者：
Du, Liangcheng
中科院分区：
文献类型：
--
作者：
Yu, Fengan;Zaleta-Rivera, Kathia;Du, Liangcheng
从产酶溶杆菌菌株C3中筛选抗真菌化合物，该菌株是真菌病害的细菌生物防治剂，先前已分离出热稳定抗真菌因子（HSAF）。HSAF对广泛的真菌物种具有抑制活性，并通过破坏一组不同的鞘脂的生物合成显示出一种新的抗真菌作用模式。我们现在已经确定了HSAF的化学结构，这是相同的dilrydromaltophilin，一种抗真菌代谢产物，具有独特的大环内酰胺系统，含有特特拉姆酸部分和5，5，6-三环骨架。我们还确定了负责菌株C3中HSAF生物合成的遗传位点。该位点的DNA测序揭示了杂合聚酮酶-非核糖体肽合成酶（PKS-NRPS）、甾醇去饱和酶、铁氧还蛋白还原酶和谷胱甘肽还原酶的基因。PKS-NRPS基因的破坏产生C3突变体，其失去产生HSAF和抑制真菌生长的能力，证明了杂合PKS-NRPS，其催化独特的大环内酰胺系统的生物合成，所述大环内酰胺系统存在于从海洋生物分离的许多生物活性天然产物中。此外，我们已经产生了突变体与破坏甾醇去饱和酶，铁氧还蛋白还原酶，和脱氢酶，并检查在这些突变体中产生的代谢产物。这项工作代表了含特特拉姆酸的大环内酰胺生物合成的遗传基础的第一次研究。HSAF化学结构的阐明及其生物合成的遗传位点的鉴定，为今后开发该类化合物作为新的杀菌剂或抗真菌药物奠定了基础。
A screen for antifungal compounds from Lysobacter enzymogenes strain C3, a bacterial biological control agent of fungal diseases, has previously led to the isolation of heat-stable antifungal factor (HSAF). HSAF exhibits inhibitory activities against a wide range of fungal species and shows a novel mode of antifungal action by disrupting the biosynthesis of a distinct group of sphingolipids. We have now determined the chemical structure of HSAF, which is identical to that of dilrydromaltophilin, an antifungal metabolite with a unique macrocyclic lactam system containing a tetramic acid moiety and a 5,5,6-tricyclic skeleton. We have also identified the genetic locus responsible for the biosynthesis of HSAF in strain C3. DNA sequencing of this locus revealed genes for a hybrid polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS), a sterol desaturase, a ferredoxin reductase, and an arginase. The disruption of the PKS-NRPS gene generated C3 mutants that lost the ability to produce HSAF and to inhibit fungal growth, demonstrating a hybrid PKS-NRPS that catalyzed the biosynthesis of the unique macrolactam system that is found in many biologically active natural products isolated from marine organisms. In addition, we have generated mutants with disrupted sterol desaturase, ferredoxin reductase, and arginase and examined the metabolites produced in these mutants. The work represents the first study of the genetic basis for the biosynthesis of the tetramic acid-containing macrolactams. The elucidation of the chemical structure of HSAF and the identification of the genetic locus for its biosynthesis establish the foundation for future exploitation of this group of compounds as new fungicides or antiftingal drugs.