Table_5_Impact of the White Collar Photoreceptor WcoA on the Fusarium fujikuroi Transcriptome.XLSX

The proteins of the White Collar 1 family (WC) constitute a major class of flavin photoreceptors, widely distributed in fungi, that work in cooperation with a WC 2 protein forming a regulatory complex. The WC complex was investigated in great detail in Neurospora crassa, a model fungus in photobiology studies, where it controls all its major photoresponses. The fungus Fusarium fujikuroi, a model system in the production of secondary metabolites, contains a single WC-1 gene called wcoA. The best-known light response in this fungus is the photoinduction of the synthesis of carotenoids, terpenoid pigments with antioxidant properties. Loss of WcoA in F. fujikuroi results in a drastic reduction in the mRNA levels of the carotenoid genes, and a diversity of morphological and metabolic changes, including alterations in the synthesis of several secondary metabolites, suggesting a complex regulatory role. To investigate the function of WcoA, the transcriptome of F. fujikuroi was analyzed in the dark and after 15-, 60- or 240-min illumination in a wild strain and in a formerly investigated wcoA insertional mutant. Using a threshold of four-fold change in transcript levels, 298 genes were activated and 160 were repressed in the wild strain under at least one of the light exposures. Different response patterns were observed among them, with genes exhibiting either fast, intermediate, and slow photoinduction, or intermediate or slow repression. All the fast and intermediate photoresponses, and most of the slow ones, were lost in the wcoA mutant. However, the wcoA mutation altered the expression of a much larger number of genes irrespective of illumination, reaching at least 16% of the annotated genes in this fungus. Such genes include many related to secondary metabolism, as well as others related to photobiology and other cellular functions, including the production of hydrophobins. As judged by the massive transcriptomic changes exhibited by the wcoA mutant in the dark, the results point to WcoA as a master regulatory protein in F. fujikuroi, in addition to a central function as the photoreceptor responsible for most of the transcriptional responses to light in this fungus.

White Collar 1家族（White Collar 1, WC）蛋白是一类主要的黄素光受体，广泛分布于真菌界，需与WC2蛋白协同作用形成调控复合物。粗糙脉孢霉（Neurospora crassa）是光生物学研究中的经典模式真菌，其WC复合物已被深入解析，该复合物调控其所有主要的光响应过程。藤仓赤霉（Fusarium fujikuroi）是次生代谢产物生产研究的模式系统，其基因组仅携带一个WC-1基因，命名为wcoA。该真菌中最具代表性的光响应为类胡萝卜素的光诱导合成——这类萜类色素具备抗氧化活性。敲除藤仓赤霉的wcoA基因会导致类胡萝卜素合成基因的mRNA水平大幅下降，同时引发多种形态与代谢变化，包括多种次生代谢产物合成的改变，这提示WcoA具有复杂的调控功能。为探究WcoA的功能，本研究对野生型菌株及此前已报道的wcoA插入突变体菌株，分别在黑暗条件以及光照15、60、240分钟后的转录组进行了分析。以转录水平变化4倍为差异阈值，野生型菌株在至少一种光照时长下共有298个基因被激活、160个基因被抑制。这些基因呈现出多样的响应模式：部分基因表现为快速、中等或缓慢的光诱导，其余则表现为中等或缓慢的光抑制。在wcoA突变体中，所有快速与中等强度的光响应，以及多数缓慢光响应均完全丧失。但无论是否处于光照条件，wcoA突变均改变了数量更为庞大的基因的表达，这部分基因至少占该真菌已注释基因的16%。这类基因包含大量与次生代谢相关的序列，以及其他参与光生物学过程与其他细胞功能的基因，其中包括疏水蛋白（hydrophobins）的合成相关基因。结合wcoA突变体在黑暗条件下即呈现出的大规模转录组变化，本研究结果表明：WcoA不仅是介导该真菌绝大多数光响应转录调控的核心光受体，同时也是藤仓赤霉中的一类主控调控蛋白。