Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, China.
State Key Laboratory of Genetic Engineering, Shanghai Public Health Clinical Center, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China.
EMBO J. 2020 Mar 16;39(6):e103412. doi: 10.15252/embj.2019103412. Epub 2020 Feb 24.
Bacterial cyclic-di-GMP (c-di-GMP) production is associated with biofilm development and the switch from acute to chronic infections. In Pseudomonas aeruginosa, the diguanylate cyclase (DGC) SiaD and phosphatase SiaA, which are co-transcribed as part of a siaABCD operon, are essential for cellular aggregation. However, the detailed functions of this operon and the relationships among its constituent genes are unknown. Here, we demonstrate that the siaABCD operon encodes for a signaling network that regulates SiaD enzymatic activity to control biofilm and aggregates formation. Through protein-protein interaction, SiaC promotes SiaD diguanylate cyclase activity. Biochemical and structural data revealed that SiaB is an unusual protein kinase that phosphorylates SiaC, whereas SiaA phosphatase can dephosphorylate SiaC. The phosphorylation state of SiaC is critical for its interaction with SiaD, which will switch on or off the DGC activity of SiaD and regulate c-di-GMP levels and subsequent virulence phenotypes. Collectively, our data provide insights into the molecular mechanisms underlying the modulation of DGC activity associated with chronic infections, which may facilitate the development of antimicrobial drugs.
细菌环二鸟苷酸 (c-di-GMP) 的产生与生物膜的发展以及急性感染向慢性感染的转变有关。在铜绿假单胞菌中，双鸟苷酸环化酶 (DGC) SiaD 和磷酸酶 SiaA 作为 siaABCD 操纵子的一部分共同转录，对于细胞聚集是必不可少的。然而，该操纵子的详细功能及其组成基因之间的关系尚不清楚。在这里，我们证明 siaABCD 操纵子编码了一个信号网络，该网络调节 SiaD 的酶活性，以控制生物膜和聚集物的形成。通过蛋白-蛋白相互作用，SiaC 促进 SiaD 双鸟苷酸环化酶的活性。生化和结构数据表明 SiaB 是一种不寻常的蛋白激酶，可磷酸化 SiaC，而 SiaA 磷酸酶可以去磷酸化 SiaC。SiaC 的磷酸化状态对于其与 SiaD 的相互作用至关重要，这将开启或关闭 SiaD 的 DGC 活性，并调节 c-di-GMP 水平和随后的毒力表型。总的来说，我们的数据提供了对与慢性感染相关的 DGC 活性调节的分子机制的深入了解，这可能有助于开发抗菌药物。
