Alvarez Adrián F, Santillán-Jiménez Antonio de Jesús, Flores-Tamayo Eder, Teran-Melo Juan L, Vázquez-Ciros Oscar J, Georgellis Dimitris
Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City, México.
Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, KY, United States of America.
PLoS One. 2024 Dec 5;19(12):e0315238. doi: 10.1371/journal.pone.0315238. eCollection 2024.
Bacteria employ two-component signal transduction systems (TCS) to sense environmental fluctuations and adjust their cellular functions. The Arc TCS is crucial for facultative anaerobes as it enables adaptation to varying respiratory conditions. The Escherichia coli ArcB detects redox changes through two cysteine amino acid residues within its PAS domain. However, the ArcB homologs from most bacteria belonging to the Pasteurellaceae family, lack the entire PAS domain, and in consequence the two regulatory cysteine amino acid residues. In this study, we show that the PAS-less ArcB of Haemophilus influenzae regulates its activity via a cysteine-independent mechanism, and we provide data suggesting that it responds to metabolic signals rather than redox cues. Thus, these two ArcB orthologs sense distinct signals and their regulatory mechanism rely on different molecular events. Our findings reveal divergent evolutionary trajectories of these ArcB homologs, despite the overall conservation of protein components, providing an example of how evolution has shaped different sensing strategies in bacteria.
细菌利用双组分信号转导系统（TCS）来感知环境波动并调节其细胞功能。Arc TCS对兼性厌氧菌至关重要，因为它能使细菌适应不同的呼吸条件。大肠杆菌的ArcB通过其PAS结构域内的两个半胱氨酸氨基酸残基检测氧化还原变化。然而，大多数巴斯德氏菌科细菌的ArcB同源物缺乏整个PAS结构域，因此也缺乏两个调节性半胱氨酸氨基酸残基。在本研究中，我们表明流感嗜血杆菌无PAS结构域的ArcB通过一种不依赖半胱氨酸的机制调节其活性，并且我们提供的数据表明它对代谢信号而非氧化还原信号作出反应。因此，这两种ArcB直系同源物感知不同的信号，它们的调节机制依赖于不同的分子事件。我们的研究结果揭示了这些ArcB同源物不同的进化轨迹，尽管蛋白质组分总体上是保守的，这为进化如何塑造细菌中不同的传感策略提供了一个例子。
