A polyketide macrolactone synthase from the filamentous fungus Gibberella zeae
A polyketide macrolactone synthase from the filamentous fungus Gibberella zeae
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DOI：
10.1073/pnas.0800657105
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发表时间：
2008-04-29
影响因子：
11.1
通讯作者：
Tang, Yi
中科院分区：
文献类型：
--
作者：
Zhou, Hui;Zhan, Jixun;Tang, Yi
间苯二酸内酯是一类独特的真菌多酮类化合物，具有广泛的生物活性，如Hsp90和MAPK的纳米分子抑制剂。这些化合物的生物合成被认为涉及两个真菌聚酮合成酶(PKS)，这两个酶协同作用产生一个14元大内酯，其中一个大内酯的核心是重氮杂环化合物。我们报道了赤霉菌PKS113的重组，它是与玉米赤霉烯酮生物合成相关的非还原PKS。使用模拟天然六酮起始单元的小分子，我们在体外重建了完整的Pks 13活性谱系，包括起始单元选择、迭代缩合、区域选择性C2-C7环化和大内酯形成。Pks 13既合成了天然的14元间苯二酸内酯，也合成了以前未被表征的16元间苯二酸内酯，表明在迭代延伸和大环化过程中都有松弛的控制。Pks 13对C6和C16大小不等的脂肪酰辅酶A表现出广泛的起始单位特异性，并显示出对癸酰辅酶A最高的活性。Pks 13在大肠杆菌中具有活性，在没有外源前体的情况下合成了大量的烷基吡喃和烷基间苯二酸酯。我们证明了Pks 13可以与大肠杆菌脂肪酸生物合成机制相互作用，并且可以在低微摩尔浓度下被脂肪酰基ACPp启动。当培养物中添加合成前体时，Pks 13在大肠杆菌中合成了新的多酮，展示了其在前体定向生物合成中的应用。因此，Pks 13是一种高度通用的多酮环大内酯合成酶，在多酮的工程生物合成中是有用的，包括自然界中不存在的间苯二酸内酯。
Resorcylic acid lactones represent a unique class of fungal polyketides and display a wide range of biological activities, such as nanomolar inhibitors of Hsp90 and MAP kinase. The biosynthesis of these compounds is proposed to involve two fungal polyketide synthases (PKS) that function collaboratively to yield a 14-membered macrolactone with a resorcylate core. We report here the reconstitution of Gibberella zeae PKS113, which is the nonreducing PKS associated with zearalenone biosynthesis. Using a small molecule mimic of the natural hexaketide starter unit, we reconstituted the entire repertoire of PKS13 activities in vitro, including starter-unit selection, iterative condensation, regioselective C2-C7 cyclization, and macrolactone formation. PKS13 synthesized both natural 14-membered and previously uncharacterized 16-membered resorcylic acid lactones, indicating relaxed control in both iterative elongation and macrocyclization. PKS13 exhibited broad starter-unit specificities toward fatty acyl-CoAs ranging in sizes between C6 and C16 and displayed the highest activity toward decanoyl-CoA. PKS13 was shown to be active in Escherichia coli and synthesized numerous alkyl pyrones and alkyl resorcylic esters without exogenously supplied precursors. We demonstrated that PKS13 can interact with E. coli fatty acid biosynthetic machinery and can be primed with fatty-acyl ACPp at low-micromolar concentrations. PKS13 synthesized new polyketides in E. coli when the culture was supplemented with synthetic precursors, showcasing its utility in precursor-directed biosynthesis. PKS13 is therefore a highly versatile polyketicle macrolactone synthase that is useful in the engineered biosynthesis of polyketides, including resorcylic acid lactones that are not found in nature.