Qu Mengxin, Li Lulu, Zan Xinyi, Cui Fengjie, Sun Lei, Sun Wenjing
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
Jiangxi Provincial Engineering and Technology Center for Food Additives Bio-Production, Shangrao 334221, China.
Microorganisms. 2025 Jun 15;13(6):1395. doi: 10.3390/microorganisms13061395.
The GntR is a transcriptional regulator generally known as a gluconate-operon repressor to specifically regulate the transportation and phosphorylation of gluconate. In the present study we report the cloning of the GntR-encoding gene of the industrial 2-ketogluconate (2KGA)-producer JUIM01, which is involved in the regulation of gluconate metabolism, along with the identification of some of its target genes and its operator sequence. GntR is a 36.36-kDa cytoplasmic and hydrophobic DNA-binding transcriptional regulator belonging to the LacI family. The knockout of resulted in the significant upregulation of the transcription of the gluconate kinase gene and, to a lesser extent, the permease gene , as well as downregulation of genes involved in glucose uptake (, , , , and ) and those involved in 2-ketogluconate (2KGA) transport () and catabolism (, , and ). These results indicated that GntR positively regulated glucose and 2KGA transport and catabolism, while negatively affecting GntP-mediated gluconate uptake and gluconate phosphorylation by GntK. Electrophoretic mobility shift assay (EMSA) and DNase I footprinting analyses confirmed that GntR interacted with operator sequences in the divergent promoter regions of and , as well as in the promoter region. A putative operator sequence (consensus 5'-AG-N-AGCGCT-N-TCT-3') was identified. These data suggest that GntR positively regulates genes involved in glucose uptake/transport and 2KGA transport/catabolism, while repressing its own expression as well as that of genes involved in gluconate transport/catabolism. These findings not only elucidate the regulation of GntR and its target genes in , but also provide valuable insights for optimizing industrial 2KGA production.
GntR是一种转录调节因子，通常作为葡萄糖酸操纵子阻遏物，专门调节葡萄糖酸的运输和磷酸化。在本研究中，我们报道了工业2-酮基葡萄糖酸（2KGA）生产菌株JUIM01中编码GntR的基因的克隆，该基因参与葡萄糖酸代谢的调节，同时鉴定了其一些靶基因及其操纵序列。GntR是一种36.36 kDa的细胞质和疏水性DNA结合转录调节因子，属于LacI家族。敲除该基因导致葡萄糖酸激酶基因转录显著上调，在较小程度上导致通透酶基因转录上调，同时参与葡萄糖摄取的基因（、、、、和）以及参与2-酮基葡萄糖酸（2KGA）运输（）和分解代谢（、、和）的基因转录下调。这些结果表明，GntR正向调节葡萄糖和2KGA的运输及分解代谢，同时对GntP介导的葡萄糖酸摄取和GntK介导的葡萄糖酸磷酸化产生负面影响。电泳迁移率变动分析（EMSA）和DNase I足迹分析证实，GntR与和的启动子区域以及启动子区域中的操纵序列相互作用。鉴定出一个推定的操纵序列（共有序列5'-AG-N-AGCGCT-N-TCT-3'）。这些数据表明，GntR正向调节参与葡萄糖摄取/运输和2KGA运输/分解代谢的基因，同时抑制其自身表达以及参与葡萄糖酸运输/分解代谢的基因表达。这些发现不仅阐明了中GntR及其靶基因的调控机制，也为优化工业2KGA生产提供了有价值的见解。
