CSRS, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
Chembiochem. 2019 Mar 1;20(5):693-700. doi: 10.1002/cbic.201800620. Epub 2019 Jan 23.
Most fungal secondary metabolism genes are poorly expressed under laboratory conditions. Nectriapyrones are known as secondary metabolites produced mainly by symbiotic fungi, including endophytes and plant pathogens. Herein, we show the induction of nectriapyrone production in the rice blast fungus Pyricularia oryzae. The two-component signal transduction system was disturbed by disrupting OSM1 and PoYPD1, which encoded a HOG MAP kinase and a His-containing phosphotransfer (HPt) protein, respectively. This induced the production of two polyketide compounds: nectriapyrone and its hydroxylated analogue. The nectriapyrone biosynthetic gene cluster consists of a polyketide synthase gene (NEC1) and an O-methyltransferase gene (NEC2). Overexpression of the two genes induced overproduction of nectriapyrone and five nectriapyrone analogues, including a new derivative. Nectriapyrone production was not required for the infection of rice. The structure of nectriapyrone is similar to that of the germicidins produced by Streptomyces spp., and nectriapyrone inhibited the growth of Streptomyces griseus.
大多数真菌次生代谢基因在实验室条件下表达水平较低。Nectriapyrones 是一类主要由共生真菌（包括内生真菌和植物病原菌）产生的次生代谢产物。本文报道了稻瘟病菌（Pyricularia oryzae）中 nectriapyrone 产生的诱导。通过敲除 OSM1 和 PoYPD1（分别编码 HOG MAP 激酶和含组氨酸的磷酸转移（HPt）蛋白）破坏了双组分信号转导系统，从而诱导了两种聚酮化合物：nectriapyrone 和其羟基化类似物的产生。nectriapyrone 的生物合成基因簇由一个聚酮合酶基因（NEC1）和一个 O-甲基转移酶基因（NEC2）组成。这两个基因的过表达诱导了 nectriapyrone 和五种 nectriapyrone 类似物（包括一种新衍生物）的过量产生。nectriapyrone 的产生对于水稻的侵染并非必需。nectriapyrone 的结构与灰色链霉菌产生的 germicidins 相似，并且 nectriapyrone 抑制灰色链霉菌的生长。
