Pardo-Medina Javier, Gutiérrez Gabriel, Limón M Carmen, Avalos Javier
Department of Genetics, Faculty of Biology, University of Seville, Seville, Spain.
Front Microbiol. 2021 Jan 18;11:619474. doi: 10.3389/fmicb.2020.619474. eCollection 2020.
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 , a model fungus in photobiology studies, where it controls all its major photoresponses. The fungus , a model system in the production of secondary metabolites, contains a single WC-1 gene called . 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 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 was analyzed in the dark and after 15-, 60- or 240-min illumination in a wild strain and in a formerly investigated 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 mutant. However, the 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 mutant in the dark, the results point to WcoA as a master regulatory protein in , in addition to a central function as the photoreceptor responsible for most of the transcriptional responses to light in this fungus.
白领1家族（WC）的蛋白质构成了一类主要的黄素光感受器，广泛分布于真菌中，它们与WC2蛋白协同作用形成一个调节复合体。在光生物学研究中的模式真菌里，对WC复合体进行了非常详细的研究，在该真菌中它控制着所有主要的光反应。在次级代谢产物生产中的模式系统真菌含有一个名为WcoA的单一WC-1基因。这种真菌中最著名的光反应是类胡萝卜素（具有抗氧化特性的萜类色素）合成的光诱导。在该真菌中WcoA的缺失导致类胡萝卜素基因的mRNA水平急剧下降，以及多种形态和代谢变化，包括几种次级代谢产物合成的改变，这表明其具有复杂的调节作用。为了研究WcoA的功能，在野生菌株和先前研究的插入突变体中，于黑暗中以及光照15分钟、60分钟或240分钟后对该真菌的转录组进行了分析。使用转录水平四倍变化的阈值，在至少一种光照条件下，野生菌株中有298个基因被激活，160个基因被抑制。在它们之间观察到了不同的反应模式，基因表现出快速、中间和缓慢的光诱导，或中间或缓慢的抑制。在插入突变体中，所有快速和中间的光反应以及大多数缓慢的光反应都消失了。然而，该突变改变了大量基因的表达，无论是否光照，达到了该真菌中至少16%的注释基因。这些基因包括许多与次级代谢相关的基因，以及其他与光生物学和其他细胞功能相关的基因，包括疏水蛋白的产生。从插入突变体在黑暗中表现出的大量转录组变化来看，结果表明WcoA不仅是该真菌中负责大多数对光的转录反应的光感受器的核心功能，还是一个主要调节蛋白。
