Cai Xun-Chao, Xi Huan, Liang Li, Liu Jia-Dong, Liu Chang-Hong, Xue Ya-Rong, Yu Xiang-Yang
State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University Nanjing, China.
Institute of Food Safety and Inspection - Jiangsu Academy of Agricultural Sciences Nanjing, China.
Front Microbiol. 2017 Feb 13;8:178. doi: 10.3389/fmicb.2017.00178. eCollection 2017.
Rifampicin resistance (Rif) mutations in the RNA polymerase β subunit () gene exhibit pleiotropic phenotypes as a result of their effects on the transcription machinery in prokaryotes. However, the differences in the effects of the mutations on the physiology and metabolism of the bacteria remain unknown. In this study, we isolated seven Rif mutations in , including six single point mutations (H485Y, H485C, H485D, H485R, Q472R, and S490L) and one double point mutation (S490L/S617F) from vegetative cells of an endophytic strain, CC09. Compared to the wild-type (WT) strain (CC09), the H485R and H485D mutants exhibited a higher degree of inhibition of spore germination, while the H485Y, S490L, Q472R, and S490L/S617F mutants exhibited a lower degree of inhibition due to their lower production of the antibiotic iturin A. These mutants all exhibited defective phenotypes in terms of pellicle formation, sporulation, and swarming motility. A hierarchical clustering analysis of the observed phenotypes indicated that the four mutations involving amino acid substitutions at H485 in RpoB belonged to the same cluster. In contrast, the S490L and Q472R mutations, as well as the WT strain, were in another cluster, indicating a functional connection between the mutations in and phenotypic changes. Our data suggest that Rif mutations cannot only be used to study transcriptional regulation mechanisms, but can also serve as a tool to increase the production of bioactive metabolites in .
RNA聚合酶β亚基（）基因中的利福平抗性（Rif）突变由于其对原核生物转录机制的影响而表现出多效性表型。然而，这些突变对细菌生理和代谢影响的差异仍不清楚。在本研究中，我们从内生菌株CC09的营养细胞中分离出7个Rif突变，包括6个单点突变（H485Y、H485C、H485D、H485R、Q472R和S490L）和1个双点突变（S490L/S617F）。与野生型（WT）菌株（CC09）相比，H485R和H485D突变体对孢子萌发的抑制程度更高，而H485Y、S490L、Q472R和S490L/S617F突变体由于其抗生素iturin A产量较低，抑制程度较低。这些突变体在菌膜形成、孢子形成和群体运动方面均表现出缺陷表型。对观察到的表型进行层次聚类分析表明，RpoB中涉及H485氨基酸替换的4个突变属于同一簇。相比之下，S490L和Q472R突变以及WT菌株则在另一簇中，这表明中的突变与表型变化之间存在功能联系。我们的数据表明，Rif突变不仅可用于研究转录调控机制，但也可以作为一种工具来增加中的生物活性代谢产物的产量。
