Predicted Glycerol 3-Phosphate Dehydrogenase Homologs and the Glycerol Kinase GlcA Coordinately Adapt to Various Carbon Sources and Osmotic Stress in Aspergillus fumigatus.
Predicted Glycerol 3-Phosphate Dehydrogenase Homologs and the Glycerol Kinase GlcA Coordinately Adapt to Various Carbon Sources and Osmotic Stress in Aspergillus fumigatus.
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预测的 3-磷酸甘油脱氢酶同系物和甘油激酶 GlcA 协调适应烟曲霉中的各种碳源和渗透压
DOI：
10.1534/g3.118.200253
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发表时间：
2018-07-02
期刊：
影响因子：
--
通讯作者：
Lu L
中科院分区：
文献类型：
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作者：
Zhang C;Meng X;Gu H;Ma Z;Lu L
甘油在真菌适应各种微环境和应激源（包括热休克、缺氧条件和渗透应激）方面发挥着重要作用。 3-磷酸甘油脱氢酶（G3PDH）能够催化磷酸二羟丙酮生成3-磷酸甘油（G3P），随后再去磷酸化为甘油。然而，目前关于 G3PDH 同系物在烟曲霉甘油生物合成中的功能的知识有限。在这里，我们证明烟曲霉 G3PDH 基因 gfdA 对于常氧和低氧条件下葡萄糖培养基中的正常菌落生长至关重要。此外，gfdA 同源物 gfdB 的过表达未能挽救 gfdA 无效突变体的表型，这表明 gfdA 在 G3P 和甘油的合成中起着主导作用。然而，在野生型背景下，过表达 gfdA 或 gfdB 能够显着提高菌丝体的生物量产量，表明 gfdA 和 gfdB 在促进葡萄糖利用方面具有相似的功能。有趣的是，编码预测的甘油激酶GlcA的基因的过表达能够将甘油磷酸化形成G3P，显着挽救了gfdA无效突变体在葡萄糖培养基中的生长缺陷，表明gfdA无效突变体的生长缺陷可能是由于G3P的缺乏而不是甘油造成的。此外，蛋白质印迹分析表明，gfdA 是由渗透介质诱导表达的。然而，在缺乏 gfdA 的情况下，渗透压可以挽救集落生长缺陷，并允许集落以高渗透压甘油途径依赖性方式部分绕过 gfdA 需求。因此，这项研究的结果阐明了腐生丝状真菌如何发展出与芽殖酵母不同的途径来适应不同的碳源并在环境压力下生存。
Glycerol plays an important role in the adaptation of fungi to various microenvironments and stressors, including heat shock, anoxic conditions and osmotic stress. Glycerol 3-phosphate dehydrogenase (G3PDH) is able to catalyze dihydroxyacetone phosphate to glycerol 3-phosphate (G3P), which is subsequently dephosphorylated into glycerol. However, current knowledge about the functions of G3PDH homologs in glycerol biosynthesis in Aspergillus fumigatus is limited. Here, we show that the A. fumigatus G3PDH gene, gfdA, is crucial for normal colony growth in glucose media under both normoxic and hypoxic conditions. In addition, failure of the overexpression of the gfdA homolog, gfdB, to rescue the phenotype of a gfdA null mutant suggests that gfdA plays a predominant role in the synthesis of G3P and glycerol. However, in a wild-type background, overexpressing either gfdA or gfdB is able to significantly enhance biomass production of mycelia, suggesting that gfdA and gfdB have similar functions in promoting the use of glucose. Interestingly, overexpression of the gene encoding the predicted glycerol kinase, GlcA, which is capable of phosphorylating glycerol to form G3P, significantly rescues the growth defects of gfdA null mutants in glucose media, indicating that the growth defects of gfdA null mutants might be due to the absence of G3P rather than glycerol. Moreover, Western blotting analysis revealed that gfdA is inducibly expressed by osmotic mediators. However, in the absence of gfdA, osmotic stress can rescue colony growth defects and allow colonies to partially bypass the gfdA requirement in a high osmolarity glycerol pathway-dependent manner. Therefore, the findings of this study elucidate how saprophytic filamentous fungi have developed pathways distinct from those of budding yeasts to adapt to varied carbon sources and survive environmental stresses.