Sun Yang, Wang Lijun, Pan Xuewei, Osire Tolbert, Fang Haitian, Zhang Huiling, Yang Shang-Tian, Yang Taowei, Rao Zhiming
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China.
Ningxia Key Laboratory for Food Microbial-Applications Technology and Safety Control, Yinchuan, China.
Front Bioeng Biotechnol. 2020 Jun 3;8:344. doi: 10.3389/fbioe.2020.00344. eCollection 2020.
Prodigiosin (PG) is a typical secondary metabolite mainly produced by . CpxR protein is an OmpR family transcriptional regulator in Gram-negative bacteria. Firstly, it was found that insertion mutation of in JNB 5-1 by a transposon Tn5G increased the production of PG. Results from the electrophoretic mobility shift assay (EMSA) indicated that CpxR could bind to the promoter of the gene cluster and repress the transcription levels of genes involved in PG biosynthesis in JNB 5-1. In the Δ mutant strain, the transcription levels of the gene cluster and the genes involved in the pathways of PG precursors, such as proline, pyruvate, serine, methionine, and S-adenosyl methionine, were significantly increased, hence promoting the production of PG. Subsequently, a fusion segment composed of the genes , and , responsible for proline, serine, and methionine, was inserted into the gene in JNB 5-1. On fermentation by the resultant engineered , the highest PG titer reached 5.83 g/L and increased by 41.9%, relative to the parental strain. In this study, we revealed the role of CpxR in PG biosynthesis and provided an alternative strategy for the engineering of to enhance PG production.
灵菌红素（PG）是一种典型的次级代谢产物，主要由……产生。CpxR蛋白是革兰氏阴性菌中的一种OmpR家族转录调节因子。首先，发现转座子Tn5G对JNB 5-1中的……进行插入突变可增加PG的产量。电泳迁移率变动分析（EMSA）结果表明，CpxR可与……基因簇的启动子结合，并抑制JNB 5-1中参与PG生物合成的基因的转录水平。在Δ突变株中，……基因簇以及参与PG前体途径的基因（如脯氨酸、丙酮酸、丝氨酸、蛋氨酸和S-腺苷甲硫氨酸）的转录水平显著增加，从而促进了PG的产生。随后，将负责脯氨酸、丝氨酸和蛋氨酸的……、……和……基因组成的融合片段插入JNB 5-1的……基因中。用所得工程菌发酵时，PG的最高滴度达到5.83 g/L，相对于亲本菌株增加了41.9%。在本研究中，我们揭示了CpxR在PG生物合成中的作用，并为工程改造……以提高PG产量提供了一种替代策略。
