The NreA/NreB sensors of Staphylococcus carnosus: A sensor complex for coordinated-sensing of O2 and nitrate.

肉葡萄球菌的 NreA/NreB 传感器：协调传感 O2 和硝酸盐的传感器复合物。

• 批准号: 260693735
• 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: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/260693735?language=en
• 关键词: NreA; NreB; sensors; Staphylococcus; carnosus

Bacteria respond rapidly to environmental stimuli, and adapt cellular composition, metabolism and other properties to optimal growth and survival. Electron acceptors like O2 and nitrate represent major stimuli for many bacteria that control expression of many genes, including those for aerobic and anaerobic respiration, fermentation, but also virulence and biotechnologically relevant traits. In Staphylococci response to O2 and nitrate turned out to use new components and to follow new strategies. The oxygen sensor NreB is part of a cytoplasmic two-component system (NreB/NreC). The NreB sensor kinase consists of a sensory PAS domain that binds a labile [4Fe-4S]2+ cluster for O2-sensing which is degraded by O2 to a [2Fe-2S]2+ cluster, and then completely lost, forming apoNreB. The latter forms are inactive in transcriptional activation of the genes of nitrate respiration. The nitrate receptor NreA is a small cytoplasmic GAF domain protein that binds nitrate at the active site. The structure of this novel nitrate receptor was characterized in collaboration with T. Stehle (Tübingen). Interaction between O2 and nitrate sensing was continued in Mainz. NreA interacts directly with NreB, and the interaction is controlled by nitrate. Nitrate-free NreA binds to NreB which is then inhibited in autophosphorylation. Consequently, phosphorylation of NreC and expression of target genes is decreased. The NreA/NreB interaction and inhibition of NreB phosphorylation is relieved when NreA exists in the nitrate-bound form. Thus NreA and NreB cooperate in a NreA/NreB sensor complex, where the primary sensor NreB is modulated in activity by the nitrate-receptor NreA; NreA is not able of directly controlling target genes. This mode of O2/nitrate sensing is in fundamental contrast to that of other bacteria like E. coli, Bacillus, Pseudomonas.The novel NreA/NreB sensor complex will be characterized at the molecular level for its characteristic properties regarding NreA/NreB interaction and control of the O2-sensor NreB by NreA and nitrate. Thus (i) the physical interaction sites on NreA and NreB, and (ii) the sites in NreB for the intramolecular signal transfer (FeS cluster, PAS domain regions, kinase domain) that are modulated by NreA, shall be identified at the molecular level. In addition (iii), NreB contains an active phosphatase domain, which will be characterized in its role for NreB activity. Structural studies (iv) on NreB have been started and will be continued (collaboration with R. Lancaster, Homburg).

细菌对环境刺激反应迅速，并使细胞组成、代谢和其他特性适应最佳生长和存活。O2和硝酸盐等电子受体是许多细菌的主要刺激物，这些细菌控制许多基因的表达，包括有氧和无氧呼吸、发酵基因，以及毒力和生物技术相关性状。在葡萄球菌响应O2和硝酸盐原来使用新的组件，并遵循新的策略。氧传感器NreB是细胞质双组分系统（NreB/NreC）的一部分。NreB传感器激酶由感觉PAS结构域组成，其结合不稳定的[4Fe-4S]2+簇用于O2-传感，其被O2降解为[2Fe-2S]2+簇，然后完全丢失，形成apoNreB。后一种形式在硝酸盐呼吸基因的转录激活中是无活性的。硝酸盐受体NreA是在活性位点结合硝酸盐的小细胞质GAF结构域蛋白。与T.施特勒（图宾根）。O2和硝酸盐传感之间的相互作用继续在美因茨。NreA与NreB直接相互作用，相互作用受硝酸盐控制。不含硝酸盐的NreA与NreB结合，然后抑制自磷酸化。因此，NreC的磷酸化和靶基因的表达降低。当NreA以硝酸盐结合形式存在时，NreA/NreB相互作用和NreB磷酸化的抑制被缓解。因此，NreA和NreB在NreA/NreB传感器复合物中合作，其中初级传感器NreB的活性由硝酸盐受体NreA调节; NreA不能直接控制靶基因。这种O2/硝酸盐传感模式与其他细菌如E.新型NreA/NreB传感器复合物将在分子水平上表征其关于NreA/NreB相互作用和NreA和硝酸盐对O2传感器NreB的控制的特征性质。因此，（i）NreA和NreB上的物理相互作用位点，以及（ii）NreB中受NreA调节的分子内信号传递位点（FeS簇，PAS结构域区域，激酶结构域），应在分子水平上进行鉴定。此外（iii），NreB含有活性磷酸酶结构域，其特征在于其对NreB活性的作用。关于NreB的结构研究（iv）已经开始，并将继续进行（与R.兰开斯特、洪堡）。