Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
Environ Microbiol. 2015 Apr;17(4):994-1008. doi: 10.1111/1462-2920.12451. Epub 2014 Apr 2.
pH-responsive transcription factor of the PacC/Rim101 family governs adaptation to environment, development and virulence in many fungal pathogens. In this study, we report the functions of a PacC homologue, MrpacC, in an insect pathogenic fungus Metarhizium robertsii. The gene was highly transcribed in the fungus in alkaline conditions, and deletion of MrpacC impaired fungal responses to ambient pH and salt/metal challenges but not osmotic stress. We found that MrpacC is required for fungal full virulence by contributing to penetration of insect cuticles, mycosis of insect cadavers and evasion of host immunity. In MrpacC deletion strains, the chitinase but not protease activity was reduced, which was consistent with the downregulation of groups A and C chitinase genes. Further, the glucosyltransferase genes involved in cell wall remodelling and protein glycosylation were upregulated in ΔMrpacC. MrpacC transcriptional control of chitinase and glucosyltransferase genes was verified both by the presence of PacC consensus binding motif in gene promoter regions and the promoter DNA-binding assays. The results of this study not only advances the understanding of PacC function in fungal development and virulence, but will also facilitate future studies on the mechanism(s) behind the selective control of target genes by PacC.
PacC/Rim101 家族的 pH 反应转录因子调控许多真菌病原体的环境适应、发育和毒力。在本研究中，我们报告了昆虫病原真菌玫烟色棒束孢中 PacC 同源物 MrpacC 的功能。该基因在碱性条件下在真菌中高度转录，而 MrpacC 的缺失破坏了真菌对环境 pH 值以及盐/金属胁迫的响应，但不影响渗透压胁迫。我们发现 MrpacC 通过促进昆虫表皮穿透、昆虫尸体的真菌病和逃避宿主免疫来有助于真菌的完全毒力。在 MrpacC 缺失菌株中，几丁质酶但不是蛋白酶活性降低，这与 A 组和 C 组几丁质酶基因的下调一致。此外，参与细胞壁重塑和蛋白糖基化的葡糖基转移酶基因在 ΔMrpacC 中上调。通过基因启动子区域存在 PacC 共有结合基序和启动子 DNA 结合测定验证了 MrpacC 对几丁质酶和葡糖基转移酶基因的转录调控。这项研究的结果不仅推进了我们对 PacC 在真菌发育和毒力中的功能的理解，而且还将促进对 PacC 选择性控制靶基因的机制的未来研究。
