Globin-coupled sensors constitute an important family of heme-based gas sensors, an emerging class of heme proteins. In this study, we have identified and characterized a globin-coupled sensor phosphodiesterase containing an HD-GYP domain (GCS-HD-GYP) from the human pathogen Vibrio fluvialis, which is an emerging foodborne pathogen of increasing public health concern. The amino acid sequence encoded by the AL536_01530 gene from V. fluvialis indicated the presence of an N-terminal globin domain and a C-terminal HD-GYP domain, with HD-GYP domains shown previously to display phosphodiesterase activity toward bis(3′,5′)-cyclic dimeric guanosine monophosphate (c-di-GMP), a bacterial second messenger that regulates numerous important physiological functions in bacteria, including in bacterial pathogens. Optical absorption spectral properties of GCS-HD-GYP were found to be similar to those of myoglobin and hemoglobin and of other bacterial globin-coupled sensors. The binding of O₂ to the Fe(II) heme iron complex of GCS-HD-GYP promoted the catalysis of the hydrolysis of c-di-GMP to its linearized product, 5′-phosphoguanylyl-(3′,5′)-guanosine (pGpG), whereas CO and NO binding did not enhance the catalysis, indicating a strict discrimination of these gaseous ligands. These results shed new light on the molecular mechanism of gas-selective catalytic regulation by globin-coupled sensors, with these advances apt to lead to a better understanding of the family of globin-coupled sensors, a still growing family of heme-based gas sensors. In addition, given the importance of c-di-GMP in infection and virulence, our results suggested that GCS-HD-GYP could play an important role in the ability of V. fluvialis to sense O₂ and NO in the context of host–pathogen interactions.

中文翻译：

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新鉴定的含有来自人类病原体河流弧菌的 HD-GYP 结构域的球蛋白耦合传感器磷酸二酯酶的气体选择性催化调节

球蛋白耦合传感器构成了基于血红素的气体传感器的一个重要家族，这是一类新兴的血红素蛋白。在这项研究中，我们鉴定并表征了一种来自人类病原体河流弧菌的含有 HD-GYP 结构域 (GCS-HD-GYP) 的球蛋白偶联传感器磷酸二酯酶，这是一种日益引起公众健康关注的新兴食源性病原体。来自河弧菌的AL536_01530基因编码的氨基酸序列表明存在 N 端球蛋白结构域和 C 端 HD-GYP 结构域，其中 HD-GYP 结构域先前显示出对双（3'， 5')-环状二聚鸟苷单磷酸 (c-di-GMP) 是一种细菌第二信使，可调节细菌（包括细菌病原体）中的许多重要生理功能。研究发现 GCS-HD-GYP 的光学吸收光谱特性与肌红蛋白和血红蛋白以及其他细菌珠蛋白耦合传感器的光学吸收光谱特性相似。O ₂与 GCS-HD-GYP 的 Fe(II) 血红素铁复合物的结合促进了 c-di-GMP 水解为其线性化产物 5'-磷酸鸟苷基-(3',5')- 的催化作用鸟苷 (pGpG)，而 CO 和 NO 结合不会增强催化作用，表明对这些气态配体的严格区分。这些结果为球蛋白耦合传感器气体选择性催化调节的分子机制提供了新的线索，这些进展有助于更好地了解球蛋白耦合传感器家族，这是一个仍在不断增长的基于血红素的气体传感器家族。此外，考虑到 c-di-GMP 在感染和毒力中的重要性，我们的结果表明，GCS-HD-GYP 可能在河弧菌在宿主环境中感知 O ₂和 NO的能力中发挥重要作用。病原体相互作用。