Aerts David, Hauer Esther E, Ohm Robin A, Arentshorst Mark, Teertstra Wieke R, Phippen Christopher, Ram Arthur F J, Frisvad Jens C, Wösten Han A B
Microbiology, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
Department of Molecular Microbiology and Biotechnology, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands.
Antonie Van Leeuwenhoek. 2018 Mar;111(3):311-322. doi: 10.1007/s10482-017-0952-1. Epub 2017 Sep 30.
Aspergillus niger secretes proteins throughout the colony except for the zone that forms asexual spores called conidia. Inactivation of flbA that encodes a regulator of G-protein signaling results in colonies that are unable to reproduce asexually and that secrete proteins throughout the mycelium. In addition, the ΔflbA strain shows cell lysis and has thinner cell walls. Expression analysis showed that 38 predicted transcription factor genes are differentially expressed in strain ΔflbA. Here, the most down-regulated predicted transcription factor gene, called fum21, was inactivated. Growth, conidiation, and protein secretion were not affected in strain Δfum21. Whole genome expression analysis revealed that 63 and 11 genes were down- and up-regulated in Δfum21, respectively, when compared to the wild-type strain. Notably, 24 genes predicted to be involved in secondary metabolism were down-regulated in Δfum21, including 10 out of 12 genes of the fumonisin cluster. This was accompanied by absence of fumonisin production in the deletion strain and a 25% reduction in production of pyranonigrin A. Together, these results link FlbA-mediated sporulation-inhibited secretion with mycotoxin production.
黑曲霉在整个菌落中分泌蛋白质，但形成无性孢子（称为分生孢子）的区域除外。编码G蛋白信号调节因子的flbA失活会导致菌落无法进行无性繁殖，并在整个菌丝体中分泌蛋白质。此外，ΔflbA菌株表现出细胞裂解，细胞壁更薄。表达分析表明，38个预测的转录因子基因在ΔflbA菌株中差异表达。在此，最下调的预测转录因子基因fum21被失活。Δfum21菌株的生长、分生孢子形成和蛋白质分泌均未受到影响。全基因组表达分析显示，与野生型菌株相比，Δfum21中分别有63个基因下调和11个基因上调。值得注意的是，预计参与次级代谢的24个基因在Δfum21中下调，包括伏马菌素簇12个基因中的10个。这伴随着缺失菌株中伏马菌素的不产生以及吡喃黑菌素A产量降低25%。总之，这些结果将FlbA介导的孢子形成抑制分泌与霉菌毒素产生联系起来。
