Urquhart Andrew S, Hu Jinyu, Chooi Yit-Heng, Idnurm Alexander
1School of BioSciences, University of Melbourne, Melbourne, Australia.
2School of Molecular Sciences, University of Western Australia, Perth, Australia.
Fungal Biol Biotechnol. 2019 Jul 1;6:2. doi: 10.1186/s40694-019-0072-y. eCollection 2019.
Viriditoxin is one of the 'classical' secondary metabolites produced by fungi and that has antibacterial and other activities; however, the mechanism of its biosynthesis has remained unknown.
Here, a gene cluster () responsible for viriditoxin synthesis was identified, via a bioinformatics analysis of the genomes of and that both are viriditoxin producers. The function of the eight-membered gene cluster of was characterized by targeted gene disruptions, revealing the roles of each gene in the synthesis of this molecule and establishing its biosynthetic pathway, which includes a Baeyer-Villiger monooxygenase catalyzed reaction. Additionally, a predicted catalytically-inactive hydrolase was identified as being required for the stereoselective biosynthesis of ()-viriditoxin. The subcellular localizations of two proteins (VdtA and VdtG) were determined by fusing these proteins to green fluorescent protein, to establish that at least two intracellular structures are involved in the compartmentalization of the synthesis steps of this metabolite.
The predicted pathway for the synthesis of viriditoxin was established by a combination of genomics, bioinformatics, gene disruption and chemical analysis processes. Hence, this work reveals the basis for the synthesis of an understudied class of fungal secondary metabolites and provides a new model species for understanding the synthesis of biaryl compounds with a chiral axis.
绿胶霉素是真菌产生的具有抗菌及其他活性的“经典”次级代谢产物之一；然而，其生物合成机制仍不清楚。
通过对两种绿胶霉素产生菌——曲霉和青霉的基因组进行生物信息学分析，鉴定出了一个负责绿胶霉素合成的基因簇。通过靶向基因敲除对曲霉的八元基因簇的功能进行了表征，揭示了每个基因在该分子合成中的作用，并建立了其生物合成途径，该途径包括一个由拜耳-维利格单加氧酶催化的反应。此外，一种预测的无催化活性的水解酶被确定为（）-绿胶霉素立体选择性生物合成所必需。通过将两种蛋白质（VdtA和VdtG）与绿色荧光蛋白融合，确定了它们的亚细胞定位，以证实至少有两个细胞内结构参与了这种代谢产物合成步骤的区室化。
通过基因组学、生物信息学、基因敲除和化学分析等方法相结合，确定了绿胶霉素的预测合成途径。因此，这项工作揭示了一类研究较少的真菌次级代谢产物合成的基础，并为理解具有手性轴的联芳基化合物的合成提供了一个新的模式物种。
