Identification of a hybrid PKS-NRPS required for the biosynthesis of NG-391 in Metarhizium robertsii
Identification of a hybrid PKS-NRPS required for the biosynthesis of NG-391 in Metarhizium robertsii
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DOI：
10.1007/s00294-010-0288-0
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发表时间：
2010-04-01
期刊：
影响因子：
2.5
通讯作者：
Gibson, Donna M.
中科院分区：
文献类型：
--
作者：
Donzelli, Bruno Giuliano Garisto;Krasnoff, Stuart B.;Gibson, Donna M.
罗伯特绿僵菌（以前称为绿僵菌变种绿僵菌）是一种多产的次生代谢物生产者，在遗传水平上对其知之甚少。为了建立诱变化合物NG-391生物合成的遗传基础，我们鉴定了一个19,818 kb的基因组区域，其中包含预测的多酮合成酶-非核糖体肽合成酶NGS1，以及另外五个orf。农杆菌介导的转化产生的NGS1敲除不能产生可检测水平的NG-391，这表明该位点参与了其生物合成。与野生型相比，NGS1缺失突变体对夜蛾幼虫的毒力水平和对过氧化氢氧化应激的抗性没有显著变化。这6种orf均在支持NG-391产生的培养基中表达，NGS1在与S. exigua宿主的相互作用中表达。NGS1启动子与gfp报告子融合的研究表明，在体外培养过程中，NGS1的表达仅限于早期指数期，并受robertsii细胞密度的影响。
The fungal entomopathogen Metarhizium robertsii (formerly known as M. anisopliae var. anisopliae) is a prolific producer of secondary metabolites of which very little is known at the genetic level. To establish the genetic bases for the biosynthesis of the mutagenic compound NG-391, we identified a 19,818 kb genomic region harboring the predicted hybrid polyketide synthase-nonribosomal peptide synthetase NGS1, plus five additional ORFs. NGS1 knockouts generated by Agrobacterium-mediated transformation failed to produce detectable levels of NG-391, indicating the involvement of this locus in its biosynthesis. NGS1 deletion mutants had no significant changes in virulence levels against larvae of Spodoptera exigua and in resistance to hydrogen peroxide-generated oxidative stress compared to the wild-type strain. All 6 ORFs were expressed in medium supporting production of NG-391, and NGS1 was expressed during the interaction with the S. exigua host. The use of an NGS1 promoter-GFP reporter fusion showed that during in vitro growth in still broth cultures, NGS1 expression is restricted to the early exponential phase and is affected by M. robertsii cell density.