The DctA/DcuS sensor complex of Escherichia coli: The components and their function

大肠杆菌的 DctA/DcuS 传感器复合体：组成及其功能

• 批准号: 59122837
• 负责人: Professor Dr. Gottfried Unden
• 金额: --
• 依托单位: Mikrobiologie und Weinforschung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/59122837?language=en
• 关键词: DctA; DcuS; sensor; complex; Escherichia

Bacteria are able to use a large number of membrane-bound sensor kinases for detecting environmental stimuli. The sensor kinase DcuS (C4-dicarboxylate uptake sensor) of Escherichia coli has the typical composition of a membrane bound sensor kinase with a periplasmic sensing and a cytoplasmic kinase domain. The sening domain is a PAS domain which binds the effector fumarate or other C4-dicarboxylates. DcuS requires, however, in addition secondary permeases as co-sensors for function. The succinate transporter DctA and the fumarate/succinate antiporter DcuB serve this function under aerobic and anaerobic conditions, and form sensor complexes DctA/DcuS or DcuB/DcuS, respectively. The interaction between DctA (or DcuB) and DcuS depends on specific domains of the permeases that have been identified. The work suggests that the DctA/DcuS and DcuB/DcuS sensor complexes responds to the presence of the stimulus molecule (fumarate) on the one hand directly by binding the fumarate at the periplasmic PAS domain, whereas DctA or DcuB mediate information on the transport status, and thus on the metabolic state, to DcuS. The function of this novel type of transporter/sensor complex shall be studied in vivo and in vitro in order to understand the function of the sensor complex on a molecular level. On the permease side, future studies will concentrate on DctA since this transporter can be handled and studied much easier than the anaerobic transporter DcuB.The sensor and transporter proteins of the DctA/DcuS sensor complex can be purified and reconstituted in liposomes. DcuS and DctA shall be studied in vivo and in vitro singly and in the complex. A major topic will be the question for the different roles of the sensor DcuS and of the transporter DctA in sensing, why the transporter is required in addition to the sensor for signal perception, and how the functional state of the transporter is transmitted to the sensor DcuS. Mutants are available that change the effector specificity of DcuS which will show whether DcuS alone is responsible for C4-dicarboxylate sensing. The helix8/helix8b region of DctA appears to be linked to the transport site of the transporter (helix8), and helix8b interacts with the sensor DcuS. The role of this region in transmitting the information on the transport status and functional state of DctA to the sensor will be studied in detail.We hope that work on the DctA/DcuS sensor complex will be able to provide a detailed understanding of these novel transporter/sensor complexes. It appears that dual stimuli (molecules and metabolic state) are used to control the functional state of this type of sensors, and this might be an important and more general mode of signal perception and control of sensors in bacteria and other organisms.

细菌能够使用大量的膜结合传感器激酶来检测环境刺激。大肠杆菌的传感器激酶DcuS（C4-二羧酸摄取传感器）具有膜结合传感器激酶的典型组成，其具有周质传感和胞质激酶结构域。衰老结构域是结合效应子富马酸酯或其它C4-二羧酸酯的PAS结构域。然而，DcuS需要另外的次级渗透酶作为功能的辅助传感器。琥珀酸转运蛋白DctA和富马酸/琥珀酸反向转运蛋白DcuB在有氧和厌氧条件下发挥这一功能，并分别形成传感器复合物DctA/DcuS或DcuB/DcuS。DctA（或DcuB）和DcuS之间的相互作用取决于已确定的渗透酶的特定结构域。这项工作表明，DctA/DcuS和DcuB/DcuS传感器复合物一方面直接通过在周质PAS结构域结合富马酸来响应刺激分子（富马酸）的存在，而DctA或DcuB介导关于运输状态的信息，从而介导关于代谢状态的信息。应在体内和体外研究这种新型转运蛋白/传感器复合物的功能，以便在分子水平上了解传感器复合物的功能。在通透酶方面，未来的研究将集中在DctA，因为这种转运蛋白可以处理和研究比厌氧转运蛋白DcuB容易得多。DctA/DcuS传感器复合物的传感器和转运蛋白可以纯化和重组脂质体。DcuS和DctA应在体内和体外单独和在复合物中进行研究。一个主要的主题将是传感器DcuS和转运体DctA在感测中的不同作用的问题，为什么除了用于信号感知的传感器之外还需要转运体，以及转运体的功能状态如何被传输到传感器DcuS。可获得改变DcuS的效应子特异性的突变体，这将显示DcuS是否单独负责C4-二羧酸传感。DctA的helix 8/helix 8b区域似乎与转运蛋白的转运位点（helix 8）相连，helix 8b与传感器DcuS相互作用。该区域的作用，在传输的信息上的运输状态和功能状态的DctA的传感器将详细研究。我们希望DctA/DcuS传感器复合物的工作将能够提供这些新的运输/传感器复合物的详细了解。看来，双重刺激（分子和代谢状态）是用来控制这种类型的传感器的功能状态，这可能是一个重要的和更普遍的模式的信号感知和控制的传感器在细菌和其他生物体。