College of Marine Life Sciences, Ocean University of China, Yushan Road, No. 5, Qingdao, China.
College of Marine Life Sciences, Ocean University of China, Yushan Road, No. 5, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, 266003 Qingdao, China.
Int J Biol Macromol. 2021 Dec 1;192:161-168. doi: 10.1016/j.ijbiomac.2021.09.149. Epub 2021 Sep 28.
Aureobasidium melanogenum P16, the high pullulan producer, had only one GATA type transcriptional activator AreA and one GATA type transcriptional repressor AreB. It was found that 2.4 g/L of (NH)SO had obvious nitrogen repression on pullulan biosynthesis by A. melanogenum P16. Removal of the AreB gene could make the disruptant DA6 produce 34.8 g/L pullulan while the P16 strain only produced 28.8 g/L pullulan at the efficient nitrogen condition. Further both removal of the native AreA gene and overexpression of the mutated AreA gene with non-phosphorylatable residues could render the transformant DEA12 to produce 39.8 g/L pullulan. The transcriptional levels of most of the genes related to pullulan biosynthesis in the transformant DEA12 were greatly enhanced. The mutated AreA was localized in the nuclei of the transformant DEA12 while the native AreA was distributed in the cytoplasm in A. melanogenum P16. This meant that nitrogen repression on pullulan biosynthesis in the transformant DEA12 was indeed significantly relieved. This was the first time to report that the GATA type transcriptional factors of nitrogen catabolite repression system could regulate pullulan biosynthesis in Aureobasidium spp.
聚普鲁兰高产菌 Aureobasidium melanogenum P16 仅有一个 GATA 型转录激活因子 AreA 和一个 GATA 型转录阻遏因子 AreB。研究发现，2.4 g/L 的(NH4)2SO4 对 A. melanogenum P16 的聚普鲁兰生物合成有明显的氮抑制作用。敲除 AreB 基因可使缺失突变株 DA6 产生 34.8 g/L 的聚普鲁兰，而在有效氮条件下，P16 菌株仅产生 28.8 g/L 的聚普鲁兰。进一步敲除天然的 AreA 基因并过表达具有非磷酸化残基的突变型 AreA 基因，可使转化子 DEA12 产生 39.8 g/L 的聚普鲁兰。转化子 DEA12 中与聚普鲁兰生物合成相关的大多数基因的转录水平都大大增强。突变型 AreA 定位于转化子 DEA12 的核内，而天然的 AreA 则分布在 A. melanogenum P16 的细胞质中。这意味着转化子 DEA12 中聚普鲁兰生物合成的氮阻遏作用确实得到了显著缓解。这是首次报道氮分解代谢物阻遏系统的 GATA 型转录因子可调控 Aureobasidium spp. 中的聚普鲁兰生物合成。
