Light-dependent coordination of development and secondary metabolism in the filamentous fungus Aspergillus nidulans

丝状真菌nidulans的无性繁殖在光照下加速，而封闭保护的越冬子实体内的有性孢子则优先在黑暗中形成。分化程序与不同的次级代谢途径紧密相连，次级代谢途径由基因编码，真菌中的次级代谢途径通常聚集在一个染色体上。次生代谢物生物合成基因簇在营养生长过程中被沉默，只有在特定条件下才表达，例如在发育过程中。本研究旨在研究同源/异源二聚体转录调控因子、表观遗传甲基转移酶和底物受体之间在蛋白质降解和真菌发育、毒力和次生代谢中的相互作用。重点介绍了它们在弧菌发育、次生代谢产物形成和烟曲霉致病力中的作用。天鹅绒结构域蛋白相互作用以及与不同的Vap-VIP甲基转移酶相互作用，以及E3剔除泛素连接酶的F-box蛋白底物受体将被分析。150-200个氨基酸的天鹅绒结构域为数百个真菌基因提供DNA结合和二聚化，以协调发育和次生代谢。异二聚体的形成可以通过亚基的合成和降解来控制，或者通过控制翻译后修饰的添加和移除来控制。只有天鹅绒蛋白VelB被一个内在无序结构域(IDD)的插入所打断，并且可以是两个不同的异源二聚体的一部分：VOSA-VelB延缓无性发育并促进孢子存活，而Vea-VelB支持有性发育。我们将探索插入的VelB固有无序结构域(IDD)是否提供选择性异源二聚体形成(对于VOSA)作为额外的控制水平，这可能与其他控制机制相结合，如稳定性、翻译后修饰或定位。Nidulans VAPB-VipC系统将与烟曲霉菌进行比较，后者携带两个天鹅绒相互作用蛋白VipC(VipC1，VipC2)的同源基因，包括含有或不含有VAPB的菌株，并将探讨其对致病性的影响。将通过真菌F-box蛋白受体亚基的表征来检验细胞蛋白质稳定性控制与光控真菌发育、次生代谢和毒力的遗传网络之间的联系，F-box蛋白受体亚基识别启动的底物被泛素化。核型拟青霉F-box蛋白底物受体的74个基因包括7个发育特异性受体。我们在过去几年中构建的Fbox蛋白编码基因的缺失集合，不仅可以研究天鹅绒结构域蛋白的降解，还可以研究FBX在次生代谢、胁迫响应、发育和(至少对Fbx15)毒力中的功能。

Asexual reproduction of the filamentous fungus Aspergillus nidulans is accelerated by light, whereas sexual spores within closed protecting overwintering fruiting bodies are preferentially formed in darkness. Differentiation programs are tightly connected to distinct secondary metabolic pathways, which are encoded by genes, which are in fungi often clustered on one chromosomal locus. Secondary metabolite biosynthetic gene clusters are silenced during vegetative growth and only expressed under specific conditions as e.g. during development. This research project aims to characterize the interplay between homo/hetero-dimeric transcriptional regulators, epigenetic methyltransferases and substrate receptors for protein degradation and fungal development, virulence and secondary metabolism. The focus is on their functions in development and secondary metabolite formation in A. nidulans and virulence in A. fumigatus. Velvet domain proteins interacting with each other and with different Vap-Vip methyltransferases, and F-box protein substrate receptors of E3 cullin RING ubiquitin ligases will be analyzed. The 150-200 amino acid velvet domain provides DNA binding and dimerization to hundreds of fungal genes to coordinate development and secondary metabolism. Heterodimer formation can be controlled by the synthesis and degradation of subunits or by controlled addition and removal of posttranslational modifications. Only the velvet protein VelB is interrupted by an insertion of an intrinsically disordered domain (IDD) and can be part of two different heterodimers: VosA-VelB delays asexual development and promotes spore viability, whereas VeA-VelB supports sexual development. We will explore whether the inserted VelB intrinsically disordered domain (IDD) provides selective heterodimer formation (for VosA) as additional level of control, which might be combined with other control mechanisms as stability, posttranslational modifications or location. The A. nidulans VapB-VipC system will be compared with A. fumigatus, which carries two isogenes for velvet interacting protein VipC (VipC1, VipC2) and includes strains with or without VapB and where the impact on pathogenicity will be explored. The link between cellular protein stability control and genetic networks for light-controlled fungal development, secondary metabolism and virulence will be examined through the characterization of fungal F-box protein receptor subunits, which recognize primed substrates to be ubiquitinated. The 74 genes for putative F-box protein substrate receptors of A. nidulans include seven developmental-specific receptors. The deletion collection of Fbox protein encoding genes, which we have constructed during the last years, will allow to study degradation of velvet domain proteins, but also the function of Fbx in secondary metabolism, stress response, development and (at least for Fbx15) virulence.