Polymalic acid (PMA) is a novel biopolymer produced by the polyextremotolerant fungus Aureobasidium pullulans. In this study, a GATA-family transcriptional factor, Gat1, which regulates nitrogen uptake and PMA biosynthesis, was investigated. PMA production increased to 11.2% in the mutant overexpressing gat1 but decreased to 49.1% of the PMA titre when gat1 was knocked out from the genome of A. pullulans. Comparative transcriptome analysis of wild-type and mutant strains (∆gat1 and OE::gat1) revealed that 23 common differentially expressed genes were related to oxidative phosphorylation, ribosome biogenesis, and nitrogen metabolism. Under nitrogen-limited stress, regardless of the preferred nitrogen (glutamine, Gln) or non-preferred nitrogen (proline, Pro), 70% of Gat1 in the cells was located in the nucleus-cytoplasm, which resulted in an increase in nitrogen uptake and PMA biosynthesis regulation. Quantitative RT-PCR revealed that glucosekinase (GLK) in the glycolytic pathway and malate synthase (MLS) in the glyoxylate shunt pathway may be cross-regulated by Gat1 and nitrogen concentration (Gln or Pro), Therefore, glk was overexpressed in mutant strain (OE::gat1), which resulted in an increased PMA titre and yield of 12.6% and 13.0% respectively. These findings indicate that Gat1 may play an important role in the dual regulation of the nitrogen and carbon metabolisms in PMA biosynthesis.

中文翻译：

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GATA型转录因子Gat1调节耐多聚真菌金黄色葡萄球菌（Aureobasidium pullulans）中的氮吸收和聚苹果酸的生物合成。

聚苹果酸（PMA）是一种由耐多极端性真菌Aureobasidium pullulans生产的新型生物聚合物。在这项研究中，研究了调节氮吸收和PMA生物合成的GATA家族转录因子Gat1。在过表达突变体的gat1中，PMA的产量增加到11.2％，但是当从a。pullulans的基因组中剔除gat1时，PMA的滴度下降到PMA效价的49.1％。对野生型和突变株（Δgat1和OE :: gat1）进行的转录组比较分析显示，共有23个共同差异表达的基因与氧化磷酸化，核糖体生物发生和氮代谢有关。在氮限制的胁迫下，无论优选的氮（谷氨酰胺，Gln）还是非优选的氮（脯氨酸，Pro），细胞中70％的Gat1都位于细胞核内，这导致氮吸收和PMA生物合成调节的增加。定量RT-PCR显示，糖酵解途径中的葡萄糖激酶（GLK）和乙醛酸分流途径中的苹果酸合酶（MLS）可能受Gat1和氮浓度（Gln或Pro）的交叉调控，因此，glk在突变菌株中过表达（ OE :: gat1），导致PMA滴度增加，收率分别提高12.6％和13.0％。这些发现表明，Gat1可能在PMA生物合成中氮和碳代谢的双重调控中发挥重要作用。glk在突变株（OE :: gat1）中过表达，导致PMA滴度增加，产率分别为12.6％和13.0％。这些发现表明，Gat1可能在PMA生物合成中氮和碳代谢的双重调控中发挥重要作用。glk在突变株（OE :: gat1）中过表达，导致PMA滴度增加，产率分别为12.6％和13.0％。这些发现表明，Gat1可能在PMA生物合成中氮和碳代谢的双重调控中发挥重要作用。