Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
School of Chemistry and Chemical Engineering, Shihezi University, Xinjiang, 832000, China.
Appl Microbiol Biotechnol. 2019 Jun;103(11):4539-4548. doi: 10.1007/s00253-019-09825-9. Epub 2019 Apr 17.
The MtrA-MtrB two-component regulatory system is highly conserved in Actinobacteria and plays crucial roles in cell cycle progression, cell morphology, antibiotic resistance, and osmoprotection. Previously, we revealed that the MtrA protein of Saccharopolyspora erythraea E3 strain (a high erythromycin-producing strain) had a two amino acid (H197 and V198) deletion in the DNA recognition helices of the C-terminal domain compared to the wild type S. erythraea strain NRRL2338. Here, we identified mepA (encoding a membrane protein related to metalloendopeptidases) as an MtrA target gene, and found that deleting the two amino acids in MtrA (MtrA) resulted in the loss of its DNA-binding activity for the mepA gene. The mutant MtrA lost its regulatory activity and affected various physiological functions consistent with mtrA deletion, including increased erythromycin biosynthesis, enhanced antibiotic resistance, deregulated osmoprotection, and improved transport of substances. The introduction of the wild type mtrA gene into the S. erythraea E3 strain with the mtrA gene decreased the erythromycin yield by approximately 50%, confirming that MtrA repressed erythromycin production. These findings demonstrate that MtrA is an important pleiotropic regulator of erythromycin biosynthesis, antibiotic resistance, osmoprotection, and substance transport in S. erythraea and provide new insights for improving erythromycin production. Future studies linking the molecular effects of MtrA to these phenotypes will improve our understanding of the MtrA-MtrB two-component regulatory system in Actinobacteria.
MtrA-MtrB 双组分调控系统在放线菌中高度保守，在细胞周期进程、细胞形态、抗生素抗性和渗透保护中发挥着关键作用。先前，我们揭示了来自红色糖多孢菌 E3 株（一种高红霉素产生株）的 MtrA 蛋白在 C 末端结构域的 DNA 识别螺旋中与野生型 S. erythraea NRRL2338 菌株相比有两个氨基酸（H197 和 V198）缺失。在这里，我们鉴定出 mepA（编码与金属内肽酶相关的膜蛋白）是 MtrA 的靶基因，并发现 MtrA 中的两个氨基酸缺失（MtrA）导致其对 mepA 基因的 DNA 结合活性丧失。突变 MtrA 失去了其调节活性，并影响了各种生理功能，与 mtrA 缺失一致，包括增加红霉素生物合成、增强抗生素抗性、调节渗透保护和改善物质运输。将野生型 mtrA 基因引入缺失 mtrA 基因的 S. erythraea E3 株中，使红霉素产量降低了约 50%，证实了 MtrA 抑制了红霉素的产生。这些发现表明 MtrA 是 S. erythraea 中红霉素生物合成、抗生素抗性、渗透保护和物质运输的重要多功能调节因子，并为提高红霉素产量提供了新的见解。未来将 MtrA 的分子效应与这些表型联系起来的研究将有助于我们更好地理解放线菌中的 MtrA-MtrB 双组分调控系统。
