College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China.
College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China.
Biochem Biophys Res Commun. 2022 Jan 29;590:177-183. doi: 10.1016/j.bbrc.2021.12.107. Epub 2021 Dec 30.
Gram-negative bacteria usually use acyl-homoserine lactones (AHLs)-mediated LuxI/LuxR-type quorum sensing (QS) systems for cell-cell cooperation and/or bacteria-environment communication. LuxI and LuxR are AHLs synthase and receptor, respectively. These two parts could form a positive regulatory feedback loop, controlling various types of group behaviors. However, the autoregulation mechanisms between them are fragmented and could be highly differentiated in different bacteria. Here, we clarified the autoregulation mechanism between LuxI and LuxR in Pseudoalteromonas sp. R3. YasI (LuxI in strain R3) synthesizes two types of AHLs, C8-HSL and 3-OH-C8-HSL. It is worth noting that YasR (LuxR in strain R3) only responds to C8-HSL rather than 3-OH-C8-HSL. YasR-C8HSL can activate the yasI transcription by recognizing "lux box" at yasI upstream. Interestingly, YasR can directly promote the yasR expression with AHL-independent manner, but AHL absence caused by the yasI-deficiency led to the significant decrease in the yasR expression. Further study demonstrated that the yasI-deficiency can result in the decrease in the yasR mRNA stability. Notably, both yasI-deficiency and yasR-deficiency led to the significant decrease in the expression of hfq encoding RNA chaperone. Therefore, it was speculated that not only YasR itself can directly regulate the yasR transcription, but YasR-C8HSL complex indirectly affects the yasR mRNA stability by regulating Hfq.
革兰氏阴性菌通常使用酰基高丝氨酸内酯 (AHL) 介导的 LuxI/LuxR 型群体感应 (QS) 系统进行细胞间合作和/或细菌-环境通讯。LuxI 和 LuxR 分别是 AHL 合成酶和受体。这两个部分可以形成正反馈调节回路，控制各种类型的群体行为。然而，它们之间的自我调节机制是碎片化的，在不同的细菌中可能高度分化。在这里，我们阐明了假交替单胞菌 R3 中 LuxI 和 LuxR 之间的自我调节机制。YasI（菌株 R3 中的 LuxI）合成两种类型的 AHLs，C8-HSL 和 3-OH-C8-HSL。值得注意的是，YasR（菌株 R3 中的 LuxR）仅对 C8-HSL 而不是 3-OH-C8-HSL 作出反应。YasR-C8HSL 通过识别 yasI 上游的“lux 盒”来激活 yasI 转录。有趣的是，YasR 可以以不依赖 AHL 的方式直接促进 yasR 的表达，但 yasI 缺失导致 AHL 缺失会导致 yasR 表达显著下降。进一步的研究表明，yasI 缺失会导致 yasR mRNA 稳定性下降。值得注意的是，yasI 缺失和 yasR 缺失都会导致 RNA 伴侣 Hfq 编码的 hfq 表达显著下降。因此，推测不仅 YasR 本身可以直接调节 yasR 转录，而且 YasR-C8HSL 复合物还可以通过调节 Hfq 间接影响 yasR mRNA 的稳定性。
