State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.
Department of Applied Biology, East China University of Science and Technology, Shanghai, China.
J Appl Microbiol. 2022 Aug;133(2):400-409. doi: 10.1111/jam.15568. Epub 2022 Apr 18.
Assessing the role of ramR , a gene absent in a lincomycin over-producing strain, in the regulation of morphological development and lincomycin biosynthesis in Streptomyces lincolnensis.
The gene ramR was deleted from the wild-type strain NRRL 2936 and the ΔramR mutant strain was characterized by a slower growth rate and a delayed morphological differentiation compared to the original strain NRRL 2936. Furthermore, the ΔramR produced 2.6-fold more lincomycin than the original strain, and consistently the level of expression of all lincomycin cluster located genes was enhanced at 48 and 96 h in the ΔramR. Complementation of ΔramR with an intact copy of ramR restored all wild-type features, whereas the over-expression of ramR led to a reduction of 33% of the lincomycin yield. Furthermore, the level of expression of glnR, bldA and SLCG_2919, three of known lincomycin biosynthesis regulators, was lower in the ΔramR than in the original strain at the early stage of fermentation and we demonstrated, using electrophoretic mobility shift assay and XylE reporter assay, that glnR is a novel direct target of RamR.
Altogether, these results indicated that, beyond promoting the morphological development, RamR regulates negatively lincomycin biosynthesis and positively the expression of the nitrogen regulator GlnR.
We demonstrated that RamR plays a negative role in the regulation of lincomycin biosynthesis in S. lincolnensis. Interestingly, the deletion of this gene in other antibiotic-producing Streptomyces strains might also increase their antibiotic-producing abilities.
评估 ramR 基因在林可霉素高产菌株中的缺失作用，该基因在林肯链霉菌的形态发育和林可霉素生物合成中的调控作用。
从野生型 NRRL 2936 菌株中缺失基因 ramR ，并对ΔramR 突变株的特征进行了研究，与原始菌株 NRRL 2936 相比，其生长速度较慢，形态分化延迟。此外，ΔramR 产生的林可霉素比原始菌株多 2.6 倍，并且在ΔramR 中，所有林可霉素簇定位基因的表达水平在 48 和 96 小时均增强。用完整的 ramR 基因对ΔramR 进行互补恢复了所有野生型特征，而 ramR 的过表达导致林可霉素产量降低了 33%。此外，在发酵早期，与原始菌株相比，ΔramR 中已知的林可霉素生物合成调控因子 glnR、bldA 和 SLCG_2919 的表达水平较低，我们通过电泳迁移率变动分析和 XylE 报告基因分析证明，glnR 是 RamR 的一个新的直接靶标。
总之，这些结果表明，除了促进形态发育外，RamR 还负调控林可霉素生物合成，并正调控氮调控因子 GlnR 的表达。
我们证明 RamR 在林肯链霉菌中负调控林可霉素生物合成。有趣的是，在其他抗生素产生链霉菌菌株中删除该基因也可能增加它们的抗生素产生能力。
