Structure and signaling mode of type-II ethylene receptors

对乙烯信号通路的遗传学和生物化学研究表明，参与植物激素乙烯的信号感知和信号转导的受体感受器激酶参与不同的信号通路，并整合到一个复杂的蛋白质-蛋白质相互作用网络中。该项目旨在阐明这些受体激酶的分子结构和信号模式，它们形成了两个结构和功能不同的亚家族。亚家族-I的成员具有一个保守的组氨酸激活区和一个由三个跨膜螺旋组成的感受器结构域。另一方面，亚家族-II受体缺乏组氨酸激酶活性所需的保守残基，并且在其传感器区域有一个额外的跨膜螺旋。亚家族受体-I在过去已经有了详细的描述。相比之下，我们对亚家族-II受体携带退化的组氨酸激酶域的了解要少得多。因此，我们的项目旨在通过研究与植物激素结合相关的受体的动态相互作用、受体亚型的二聚化模式以及受体与不同下游信号伙伴的相互作用来从功能上剖析II型受体在乙烯信号转导中的作用。除了通过荧光技术对受体的功能进行表征外，我们的目标是通过解决重组的II型受体的分子结构及其与下游信号伙伴的复合体或相互作用结构域来更深入地了解II型受体家族的作用。

Genetic and biochemical studies on the ethylene signaling pathway suggest that the receptor sensor kinases involved in signal perception and signal transduction of the plant hormone ethylene are engaged in different signaling pathways and are integrated into a complex network of protein-protein interactions. The project aims to elucidate the molecular structure and signaling mode of these receptor kinases, which form two structural and functional distinct subfamilies. Members of subfamily-I are characterized by a well-conserved histidine kinase domain and a sensor domain consisting of three transmembrane helices. On the other hand, subfamily-II receptors lack conserved residues necessary for histidine kinase activity and have an additional transmembrane helix in their sensor domain. Receptors of subfamily-I have been characterized in detail in the past. In contrast, our knowledge on receptors belonging to subfamily-II carrying the degenerate histidine kinase domain is much less profound. Consequently, our project aims to functionally dissect the role of type II receptors in ethylene signaling by studying dynamic interactions of the receptors related to the binding of the plant hormone, the dimerization mode of the receptor isoforms and the interaction of the receptors with different downstream signaling partners. Besides functional characterization of the receptors by fluorescence techniques we aim to get an even more mechanistic understanding of the actions of the type-II receptor family by solving the molecular structure of recombinant type-II receptors and of their complexes or interaction domains with their downstream signaling partners.