Kim Na-Kyeong, Baek Jong-Eun, Lee Ye-Jin, Oh Yuna, Oh Jeong-Il
Department of Integrated Biological Science, Pusan National University, Busan, Republic of Korea.
Microbiological Resource Research Institute, Pusan National University, Busan, Republic of Korea.
Front Microbiol. 2024 Aug 12;15:1448277. doi: 10.3389/fmicb.2024.1448277. eCollection 2024.
In this study, we demonstrated that both the expression of most ribosomal protein genes and the amount of ribosomes were decreased in the Δ mutant of , in which the major terminal oxidase ( cytochrome oxidase) of the respiratory electron transport chain (ETC) is inactivated, compared to those in the wild-type strain. Deletion of the gene encoding the major (p)ppGpp synthetase in the background of the Δ mutant restored the reduced expression of ribosomal protein genes, suggesting that inhibition of the respiratory ETC leads to the Rel-dependent stringent response (SR) in this bacterium. Both a decrease in the expression of ribosomal protein genes by overexpression of and the increased expression of in the Δ mutant relative to the wild-type strain support the Rel-dependent induction of SR in the Δ mutant. We also demonstrated that the expression of ribosomal protein genes was decreased in exposed to respiration-inhibitory conditions, such as KCN and bedaquiline treatment, null mutation of the cytochrome complex, and hypoxia. The MprBA-SigE-SigB regulatory pathway was implicated in both the increased expression of and the decreased expression of ribosomal protein genes in the Δ mutant of .
在本研究中，我们证明，与野生型菌株相比，呼吸电子传递链（ETC）的主要末端氧化酶（细胞色素c氧化酶）失活的Δ突变体中，大多数核糖体蛋白基因的表达和核糖体数量均降低。在Δ突变体背景下缺失编码主要（p）ppGpp合成酶的基因，可恢复核糖体蛋白基因降低的表达，这表明呼吸ETC的抑制导致该细菌中Rel依赖的严谨反应（SR）。通过过表达Rel使核糖体蛋白基因表达降低，以及相对于野生型菌株，Δ突变体中Rel表达增加，均支持Δ突变体中Rel依赖的SR诱导。我们还证明，在暴露于呼吸抑制条件（如KCN和贝达喹啉处理、细胞色素c复合体的无效突变和缺氧）的情况下，核糖体蛋白基因的表达降低。MprBA-SigE-SigB调节途径与Δ突变体中Rel表达增加和核糖体蛋白基因表达降低均有关。
