Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Microbiol. 2018 Nov;20(11):4063-4078. doi: 10.1111/1462-2920.14453.
The PacC (loss or reduction in phosphatase activity at acid but not at alkaline pH [Pac]) transcription factor regulates environmental adaptation, secondary metabolism and virulence in many fungal pathogens. Here, we report the functions of PacC in Penicillium expansum, a postharvest pathogenic fungus in horticultural crops, and ascertain that the gene expression and proteolytic processing of PePacC are strictly pH-dependent. Loss of PePacC resulted in an obvious decrease in growth and conidiation of P. expansum cultured in both acidic and alkaline conditions. The ΔPePacC mutant lost the ability of patulin production at pH values above 6.0 because expressions of all the genes in patulin cluster were significantly down-regulated. Additionally, virulence of the ΔPePacC mutant was obviously reduced in pear and apple fruits. Proteome analysis revealed that PePacC could function as an activator or repressor for different target proteins, including calreticulin (PeCRT) and sulfate adenylyltransferase (PeSAT), which were further proved to be involved in virulence of P. expansum. Our results demonstrate important roles for PePacC in patulin biosynthesis via limiting expressions of the genes in the cluster, and in pathogenesis via mediating a known virulence factor glucose oxidase (PeGOD) and new virulence factors, such as PeCRT and PeSAT.
PacC（酸性而非碱性 pH 值时磷酸酶活性丧失或减少的转录因子）调节许多真菌病原体的环境适应、次生代谢和毒力。在这里，我们报告了 PacC 在扩展青霉（Penicillium expansum）中的功能，扩展青霉是园艺作物采后病原菌，并且确定 PePacC 的基因表达和蛋白水解处理严格依赖 pH 值。PePacC 的缺失导致扩展青霉在酸性和碱性条件下的生长和分生孢子形成明显减少。ΔPePacC 突变体在 pH 值高于 6.0 时失去了棒曲霉素产生的能力，因为棒曲霉素簇中所有基因的表达均显著下调。此外，ΔPePacC 突变体在梨和苹果果实中的毒力明显降低。蛋白质组分析表明，PePacC 可以作为不同靶蛋白的激活剂或抑制剂，包括钙网织蛋白（PeCRT）和硫酸腺苷酰转移酶（PeSAT），这进一步证明它们参与了扩展青霉的毒力。我们的结果表明，PePacC 通过限制簇中基因的表达在棒曲霉素生物合成中起重要作用，通过介导已知的毒力因子葡萄糖氧化酶（PeGOD）和新的毒力因子，如 PeCRT 和 PeSAT，在发病机制中起重要作用。
