CreA-independent carbon catabolite repression of cellulase genes by trimeric G-protein and protein kinase A in Aspergillus nidulans
CreA-independent carbon catabolite repression of cellulase genes by trimeric G-protein and protein kinase A in Aspergillus nidulans
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DOI：
10.1007/s00294-019-00944-4
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发表时间：
2019-08-01
期刊：
影响因子：
2.5
通讯作者：
Kobayashi, Tetsuo
中科院分区：
文献类型：
--
作者：
Kunitake, Emi;Li, Yi;Kobayashi, Tetsuo
丝状真菌纤维素酶的产生受到各种碳源的抑制。在我们对中性曲霉的初步调查中，编码碳分解代谢抑制（CCR）转录抑制因子的creA突变体的去抑制程度因碳源而异。为了进一步了解纤维素酶生产CCR的机制，我们比较了creA缺失与蛋白激酶A （pkaA）和G （ganB）基因缺失的影响，这两个基因构成了一个营养感知和信号通路。在羧甲基纤维素和d-葡萄糖的平板培养中，pkaA和ganB的缺失，而creA的缺失，导致纤维素酶生产的显著去抑制。在纤维素二糖和d-葡萄糖或2-脱氧葡萄糖的深层培养中，creA或pkaA单缺失均导致纤维素酶基因的部分去抑制，其双缺失程度最高，而ganB缺失导致的去抑制程度与creA/pkaA双缺失相当。对于球磨纤维素和d-葡萄糖，通过删除creA而不是pkaA或ganB来检测部分去抑制。creA/pkaA或creA/ganB双缺失比creA缺失更早表达。此外，以d-木糖或l -阿拉伯糖作为抑制碳源的每次缺失的效果与以d-葡萄糖、d-果糖和d-甘露糖作为抑制碳源的效果显著不同。因此，本研究表明，PkaA和GanB参与了与CreA无关的CCR，并且CreA、PkaA和GanB在CCR中的贡献取决于诱导剂、抑制碳源和培养条件（平板或浸水）。需要进一步研究与crea无关的机制，以充分了解丝状真菌的CCR。
Cellulase production in filamentous fungi is repressed by various carbon sources. In our preliminary survey in Aspergillus nidulans, degree of de-repression differed depending on carbon sources in a mutant of creA, encoding the transcriptional repressor for carbon catabolite repression (CCR). To further understand mechanisms of CCR of cellulase production, we compared the effects of creA deletion with deletion of protein kinase A (pkaA) and G (ganB) genes, which constitute a nutrient sensing and signaling pathway. In plate culture with carboxymethyl cellulose and d-glucose, deletion of pkaA and ganB, but not creA, led to significant de-repression of cellulase production. In submerged culture with cellobiose and d-glucose or 2-deoxyglucose, both creA or pkaA single deletion led to partial de-repression of cellulase genes with the highest level by their double deletion, while ganB deletion caused de-repression comparable to that of the creA/pkaA double deletion. With ball-milled cellulose and d-glucose, partial de-repression was detected by deletion of creA but not of pkaA or ganB. The creA/pkaA or creA/ganB double deletion led to earlier expression than the creA deletion. Furthermore, the effect of each deletion with d-xylose or L-arabinose as the repressing carbon source was significantly different from that with d-glucose, d-fructose, and d-mannose. Consequently, this study revealed that PkaA and GanB participate in CreA-independent CCR and that contribution of CreA, PkaA, and GanB in CCR differs depending on the inducers, repressing carbon sources, and culture conditions (plate or submerged). Further study of CreA-independent mechanisms is needed to fully understand CCR in filamentous fungi.