College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, People's Republic of China.
Wenzhou Vocational College of Science & Technology, Wenzhou, 325000, Zhejiang, People's Republic of China.
Appl Microbiol Biotechnol. 2019 Apr;103(7):3099-3109. doi: 10.1007/s00253-019-09686-2. Epub 2019 Feb 20.
Cupriavidus basilensis WS degrades diphenyl ether (DE) and its lower brominated derivatives using enzymes encoded by the bph operon. However, it is not yet known under what circumstances bph genes are expressed and how they are regulated in C. basilensis WS. To answer these questions, we used transposon mutagenesis and identified a new two-component regulatory system, BphS/BphT, in C. basilensis WS, which is indispensable for the expression of the bph operon. When BphS or BphT is inactivated, C. basilensis WS no longer exhibits the ability to decompose DE. Using a β-galactosidase reporter system and RT-qPCR, we showed that bph genes are constitutively transcribed in C. basilensis WS and that deletion of bphS or bphT strongly inhibited the transcription of bph genes. We also showed that the gene ORF0, which is upstream of bphA1 and is similar to the GntR-family regulators of the bph operon, is not involved in the constitutive transcription of the bph operon in C. basilensis WS. The cis-acting elements required for the expression and regulation of bph genes in the DE degradation pathway are included in the intergenic region between ORF0 and bphA1. Our results suggest that BphS/BphT represents a new two-component regulatory system for the bph operon that is necessary for the constitutive expression of bph genes.
贪铜菌（Cupriavidus basilensis）WS 利用 bph 操纵子编码的酶来降解二苯醚（DE）及其较低溴代衍生物。然而，目前尚不清楚 bph 基因在什么情况下表达，以及在 C. basilensis WS 中它们是如何被调控的。为了回答这些问题，我们使用转座子诱变技术，在 C. basilensis WS 中鉴定出了一个新的双组分调控系统 BphS/BphT，该系统对于 bph 操纵子的表达是必不可少的。当 BphS 或 BphT 失活时，C. basilensis WS 不再表现出分解 DE 的能力。通过β-半乳糖苷酶报告系统和 RT-qPCR，我们表明 bph 基因在 C. basilensis WS 中持续转录，并且缺失 bphS 或 bphT 强烈抑制 bph 基因的转录。我们还表明，bphA1 上游的基因 ORF0 与 bph 操纵子的 GntR 家族调控因子相似，但不参与 C. basilensis WS 中 bph 操纵子的组成型转录。DE 降解途径中 bph 基因表达和调控所需的顺式作用元件包含在 ORF0 和 bphA1 之间的基因间区域。我们的结果表明，BphS/BphT 代表了 bph 操纵子的一个新的双组分调控系统，对于 bph 基因的组成型表达是必需的。
