Institute of Microbiology and College of Life Sciences, Zhejiang University, Zhejiang, Hangzhou, 310058, China.
Environ Microbiol. 2021 Feb;23(2):652-668. doi: 10.1111/1462-2920.15060. Epub 2020 Jun 3.
To survive and thrive in harsh and ever-changing environments, intricate mechanisms have evolved for bacterial cells to monitor perturbations impacting the integrity of their envelope and to mount an appropriate response to contain or repair the damage. In this study, we report in Shewanella oneidensis a previously undescribed mechanism for the envelope defect resulting from the loss of Arc, a two-component transcriptional regulatory system crucial for respiration. We uncovered σ , a master regulator establishing and maintaining the integrity of the cell envelope in γ-proteobacteria, as the determining factor for the cell envelope defect of the arcA mutant. When ArcA is depleted, σ activity is compromised by enhanced production of anti-σ protein RseA. Surprisingly, S. oneidensis σ is not essential for viability, but becomes so in the absence of ArcA. Furthermore, we demonstrated that there is an interplay between these two regulators as arcA expression is affected by availability of σ . Overall, our results underscore functional interplay of regulatory systems for envelope stress response: although each of the systems may respond to perturbation of particular components of the envelope, they are functionally intertwined, working together to form an interconnected safety net.
为了在恶劣且不断变化的环境中生存和繁荣，细菌细胞已经进化出复杂的机制来监测影响其包膜完整性的干扰，并对损伤进行适当的反应以进行包含或修复。在这项研究中，我们在希瓦氏菌属中报告了一种以前未知的机制，用于因缺失Arc 而导致的包膜缺陷，Arc 是一种对于呼吸至关重要的双组分转录调节系统。我们发现，σ是一种在γ-变形菌中建立和维持细胞包膜完整性的主要调节剂，是 arcA 突变体包膜缺陷的决定因素。当 ArcA 耗尽时，由于反σ蛋白 RseA 的产量增加，σ 的活性受到损害。令人惊讶的是，希瓦氏菌属的 σ对于生存不是必需的，但在没有 ArcA 的情况下却是必需的。此外，我们证明了这两个调节剂之间存在相互作用，因为 arcA 的表达受到 σ 的可用性的影响。总的来说，我们的结果强调了包膜应激反应的调节系统之间的功能相互作用：尽管每个系统都可能对包膜的特定成分的干扰做出反应，但它们在功能上是相互交织的，共同形成一个相互关联的安全网。
