Fairy rings resulting from a fungus–plant interaction appear worldwide. 2-Azahypoxanthine (AHX) and imidazole-4-carboxamide (ICA) were first isolated from the culture broth of one of the fairy ring-forming fungi, Lepista sordida. Afterward, a common metabolite of AHX in plants, 2-aza-8-oxohypoxanthine (AOH), was found in AHX-treated rice. The biosynthetic pathway of the three compounds that are named as fairy chemicals (FCs) in plants has been partially elucidated; however, that in mushrooms remains unknown. In this study, it was revealed that the carbon skeletons of AHX and ICA were constructed from Gly in L. sordida mycelia and the fungus metabolized 5-aminoimidazole-4-carboxamide (AICA) to both of the compounds. These results indicated that FCs were biosynthesized by a diversion of the purine metabolic pathway in L. sordida mycelia, similar to that in plants. Furthermore, we showed that recombinant adenine phosphoribosyltransferase (APRT) catalyzed reversible interconversion not only between 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5′-monophosphate (AICAR) and AICA but also between ICA-ribotide (ICAR) and ICA. Furthermore, the presence of ICAR in L. sordida mycelia was proven for the first time by LC-MS/MS detection, and this study provided the first report that there was a novel metabolic pathway of ICA in which its ribotide was an intermediate in the fungus.

中文翻译：

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仙人化学物质、2-氮杂次黄嘌呤和咪唑-4-甲酰胺在仙人成环真菌 Lepista sordida 中的生物合成。

由真菌-植物相互作用产生的仙环出现在世界各地。2-Azahypoxanthine (AHX) 和 imidazole-4-carboxamide (ICA) 首先从一种仙环形成真菌Lepista sordida的培养液中分离出来。此后，在 AHX 处理的水稻中发现了植物中 AHX 的常见代谢物 2-aza-8-oxohypoxanthine (AOH)。植物中被命名为仙人化学物（FCs）的三种化合物的生物合成途径已部分阐明；然而，蘑菇中的这一点仍然未知。在这项研究中，揭示了 AHX 和 ICA 的碳骨架是由L. sordida 中的Gly 构建的菌丝体和真菌将 5-氨基咪唑-4-甲酰胺 (AICA) 代谢为这两种化合物。这些结果表明 FC 是通过L. sordida菌丝体中嘌呤代谢途径的转移而生物合成的，类似于植物中的。此外，我们发现重组腺嘌呤磷酸核糖基转移酶 (APRT) 不仅催化 5- aminoimidazole -4-carboxamide-1-β- d -ribofuranosyl 5'-monophosphate (AICAR) 和 AICA之间的可逆互变，而且还催化ICA-核糖苷 (ICAR)之间的可逆互变和 ICA。此外，L. sordida中 ICAR 的存在 LC-MS/MS 检测首次证实了菌丝体，该研究首次报道了 ICA 存在一种新的代谢途径，其中其核糖苷是真菌的中间体。