Department of Resource and Environmental Science, School of Agriculture and Biology, Shanghai Jiao tong University, Shanghai, P. R. China; State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, P. R. China.
PLoS One. 2014 Jun 25;9(6):e100367. doi: 10.1371/journal.pone.0100367. eCollection 2014.
We investigated the properties of platelet-activating factor acetylhydrolase (PAF-AH) derived from Trichoderma harzianum. The enzyme, comprised of 572 amino acids, shares high homology with PAF-AH proteins from T. koningii and other microbial species. The optimum enzymatic activity of PAF-AH occurred at pH 6 in the absence of Ca2+ and it localized in the cytoplasm, and we observed the upregulation of PAF-AH expression in response to carbon starvation and strong heat shock. Furthermore, PAF-AH knockout transformant growth occurred more slowly than wild type cells and over-expression strains grown in SM medium at 37°C and 42°C. In addition, PAF-AH expression significantly increased under a series of maize root induction assay. Eicosanoic acid and ergosterol levels decreased in the PAF-AH knockouts compared to wild type cells, as revealed by GC/MS analysis. We also determined stress responses mediated by PAF-AH were related to proteins HEX1, Cu/Zn superoxide dismutase, and cytochrome c. Finally, PAF-AH exhibited antagonistic activity against Rhizoctonia solani in plate confrontation assays. Our results indicate PAF-AH may play an important role in T. harzianum stress response and antagonism under diverse environmental conditions.
我们研究了来自哈茨木霉的血小板激活因子乙酰水解酶（PAF-AH）的性质。该酶由 572 个氨基酸组成，与 T. koningii 和其他微生物物种的 PAF-AH 蛋白具有高度同源性。PAF-AH 的最适酶活性在无 Ca2+存在的情况下在 pH6 时发生，其定位于细胞质中，并且我们观察到 PAF-AH 表达在碳饥饿和强烈热休克时上调。此外，与野生型细胞相比，PAF-AH 敲除转化体的生长速度较慢，并且在 37°C 和 42°C 的 SM 培养基中生长的过表达株系生长速度较慢。此外，在一系列玉米根诱导试验中，PAF-AH 表达显著增加。通过 GC/MS 分析发现，与野生型细胞相比，PAF-AH 敲除株系中的二十烷酸和麦角固醇水平降低。我们还确定了 PAF-AH 介导的应激反应与蛋白质 HEX1、Cu/Zn 超氧化物歧化酶和细胞色素 c 有关。最后，PAF-AH 在平板对抗试验中对立枯丝核菌表现出拮抗活性。我们的结果表明，PAF-AH 可能在哈茨木霉应对不同环境条件下的应激和拮抗作用中发挥重要作用。
