Molecular regulation mechanisms of receptor guanylyl cyclases

第二信使cGMP在心血管系统和视力等方面具有关键作用。在哺乳动物中，一种可溶的和几种跨膜受体鸟酰环化酶（GCs）分别被一氧化氮和细胞外配体激活。哺乳动物GCs具有一个n端配体结合域、一个激酶同源域（KHD）和一个与腺苷酸环化酶同源的催化域。KHD作为负调节因子和ATP结合，而不是水解，以减轻其对催化的抑制作用。GC的另一种调节机制是ATP和gtp依赖的过程，通过小GTPase Rac1进行，激活激酶PAK，其催化结构域直接结合到GC催化结构域并增加其活性。我们建议研究小分子、PAK和内部调节剂KHD调控GC催化域的分子机制，以及如何利用人工调节剂来利用这些机制。催化区域的晶体结构将在配体的配合物中求解，以确定与ACs和GC异构体之间的差异。我们进一步研究了在存在或不存在ATP类似物的情况下，催化结构域与PAK和KHD之间的配合物结构，以揭示PAK激活和ATP与KHD结合如何导致催化结构域的激活。我们将尝试利用我们的发现为体内研究和药物开发的新型调节化合物的基于结构的设计。

The second messenger cGMP has a key function e.g. in the cardiovascular system and in vision. In mammals, a soluble and several transmembrane receptor guanylyl cyclases (GCs) are activated by nitric oxide and extracellular ligands, respectively. Mammalian GCs have an N-terminal ligand binding domain, a kinase homology domain (KHD), and a catalytic domain homologous to adenylyl cyclases. The KHD acts as a negative regulator and ATP binding, but not hydrolysis, is required in order to relieve its inhibitory effect on catalysis. Another mechanism of regulation of GC is an ATP- and GTP-dependent process proceeding via the small GTPase Rac1, which activates the kinase PAK whose catalytic domain then binds directly to the GC catalytic domain and increases its activity. We propose to study the molecular mechanisms of regulation of GC catalytic domains by small molecules, PAK, and the internal regulator KHD, and how to exploit these mechanisms with artificial modulators. Crystal structures of catalytic domains will be solved in complex with ligands in order to identify differences to ACs and between GC isoforms. We further aim to solve structures of complexes between catalytic domains and PAK and KHD in presence and absence of ATP analogs in order to reveal how PAK activation and ATP binding to the KHD lead to activation of the catalytic domain. We will attempt to exploit our findings for the structure-based design of novel regulator compounds for in vivo studies and drug development.