Division of Molecular Biology, Medical University of Innsbruck, 6020 Innsbruck, Austria.
Division of Clinical Biochemistry, Medical University of Innsbruck, 6020 Innsbruck, Austria.
Fungal Genet Biol. 2019 Aug;129:86-100. doi: 10.1016/j.fgb.2019.05.006. Epub 2019 May 28.
In filamentous fungi, arginine methylation has been implicated in morphogenesis, mycotoxin biosynthesis, pathogenicity, and stress response although the exact role of this posttranslational modification in these processes remains obscure. Here, we present the first genome-wide transcriptome analysis in filamentous fungi that compared expression levels of genes regulated by type I and type II protein arginine methyltransferases (PRMTs). In Aspergillus nidulans, three conserved type I and II PRMTs are present that catalyze asymmetric or symmetric dimethylation of arginines. We generated a double type I mutant (ΔrmtA/rmtB) and a combined type I and type II mutant (ΔrmtB/rmtC) to perform genome-wide comparison of their effects on gene expression, but also to monitor putative overlapping activities and reciprocal regulations of type I and type II PRMTs in Aspergillus. Our study demonstrates, that rmtA and rmtC as type I and type II representatives act together as repressors of proteins that are secreted into the extracellular region as the majority of up-regulated genes are mainly involved in catabolic pathways that constitute the secretome of Aspergillus. In addition to a strong up-regulation of secretory genes we found a significant enrichment of down-regulated genes involved in processes related to oxidation-reduction, transmembrane transport and secondary metabolite biosynthesis. Strikingly, nearly 50% of down-regulated genes in both double mutants correspond to redox reaction/oxidoreductase processes, a remarkable finding in light of our recently observed oxidative stress phenotypes of ΔrmtA and ΔrmtC. Finally, analysis of nuclear and cytoplasmic extracts for mono-methylated proteins revealed the presence of both, common and specific substrates of RmtA and RmtC. Thus, our data indicate that type I and II PRMTs in Aspergillus seem to co-regulate the same biological processes but also specifically affect other pathways in a non-redundant fashion.
在丝状真菌中，精氨酸甲基化被认为与形态发生、真菌毒素生物合成、致病性和应激反应有关，尽管这种翻译后修饰在这些过程中的确切作用仍不清楚。在这里，我们呈现了丝状真菌中首次全基因组转录组分析，比较了受 I 型和 II 型蛋白质精氨酸甲基转移酶（PRMT）调控的基因的表达水平。在构巢曲霉中，存在三个保守的 I 型和 II 型 PRMT，它们催化精氨酸的不对称或对称二甲基化。我们生成了一个双 I 型突变体（ΔrmtA/rmtB）和一个 I 型和 II 型的组合突变体（ΔrmtB/rmtC），以对它们对基因表达的影响进行全基因组比较，但也监测 I 型和 II 型 PRMT 之间可能存在的重叠活性和相互调节。我们的研究表明，rmtA 和 rmtC 作为 I 型和 II 型的代表，共同作为分泌到细胞外区域的蛋白质的抑制剂，因为大多数上调的基因主要参与构成曲霉分泌组的分解代谢途径。除了分泌基因的强烈上调外，我们还发现与氧化还原、跨膜运输和次生代谢物生物合成相关的过程中下调基因显著富集。引人注目的是，两个双突变体中近 50%的下调基因对应于氧化还原反应/氧化还原酶过程，这一发现与我们最近观察到的ΔrmtA 和ΔrmtC 的氧化应激表型相吻合。最后，对核和细胞质提取物中的单甲基化蛋白进行分析，发现 RmtA 和 RmtC 既有共同的，也有特异的底物。因此，我们的数据表明，曲霉中的 I 型和 II 型 PRMT 似乎共同调节相同的生物学过程，但也以非冗余的方式特异性地影响其他途径。
