Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
Nat Commun. 2024 Nov 7;15(1):9653. doi: 10.1038/s41467-024-53942-7.
The heme-based direct oxygen sensor DosP degrades c-di-GMP, a second messenger nearly unique to bacteria. In stationary phase Escherichia coli, DosP is the most abundant c-di-GMP phosphodiesterase. Ligation of O to a heme-binding PAS domain (hPAS) of the protein enhances the phosphodiesterase through an allosteric mechanism that has remained elusive. We determine six structures of full-length DosP in its aerobic or anaerobic conformations, with or without c-di-GMP. DosP is an elongated dimer with the regulatory heme containing domain and phosphodiesterase separated by nearly 180 Å. In the absence of substrate, regardless of the heme status, DosP presents an equilibrium of two distinct conformations. Binding of substrate induces DosP to adopt a single, ON-state or OFF-state conformation depending on its heme status. Structural and biochemical studies of this multi-domain sensor and its mutants provide insights into signal regulation of second-messenger levels.
血红素基直接氧传感器 DosP 会降解 c-di-GMP，c-di-GMP 是一种几乎只存在于细菌中的第二信使。在静止期的大肠杆菌中，DosP 是含量最丰富的 c-di-GMP 磷酸二酯酶。蛋白上血红素结合 PAS 结构域（hPAS）的氧结合会通过一种迄今仍难以捉摸的变构机制增强磷酸二酯酶的活性。我们确定了全长 DosP 在有氧或无氧构象下，有或没有 c-di-GMP 的情况下的六个结构。DosP 是一个拉长的二聚体，带有调节血红素的结构域和磷酸二酯酶之间的距离将近 180Å。在没有底物的情况下，无论血红素状态如何，DosP 都会呈现出两种截然不同的平衡构象。底物的结合会诱导 DosP 根据其血红素状态采用单一的 ON 状态或 OFF 状态构象。对这种多结构域传感器及其突变体的结构和生化研究为第二信使水平的信号调节提供了深入的了解。
