Duda Teresa, Pertzev Alexandre, Ravichandran Sarangan, Sharma Rameshwar K
Research Divisions of Biochemistry and Molecular Biology, The Unit of Regulatory and Molecular Biology, Salus University, Elkins Park, PA, United States.
Advanced Biomedical Computational Sciences Group, Frederick National Laboratory for Cancer Research Sponsored by the National Cancer Institute, Leidos Biomedical Research Inc., Fredrick, MD, United States.
Front Mol Neurosci. 2018 Nov 27;11:430. doi: 10.3389/fnmol.2018.00430. eCollection 2018.
Prototype member of the membrane guanylate cyclase family, ANF-RGC (Atrial Natriuretic Factor Receptor Guanylate Cyclase), is the physiological signal transducer of two most hypotensive hormones ANF and BNP, and of the intracellular free Ca. Both the hormonal and the Ca-modulated signals operate through a common second messenger, cyclic GMP; yet, their operational modes are divergent. The hormonal pathways originate at the extracellular domain of the guanylate cyclase; and through a cascade of structural changes in its successive domains activate the C-terminal catalytic domain (CCD). In contrast, the Ca signal operating via its sensor, myristoylated neurocalcin δ both originates and is translated directly at the CCD. Through a detailed sequential deletion and expression analyses, the present study examines the role of the signaling helix domain (SHD) in these two transduction pathways. SHD is a conserved 35-amino acid helical region of the guanylate cyclase, composed of five heptads, each meant to tune and transmit the hormonal signals to the CCD for their translation and generation of cyclic GMP. Its structure is homo-dimeric and the molecular docking analyses point out to the possibility of antiparallel arrangement of the helices. Contrary to the hormonal signaling, SHD has no role in regulation of the Ca- modulated pathway. The findings establish and define in molecular terms the presence of two distinct non-overlapping transduction modes of ANF-RGC, and for the first time demonstrate how differently they operate, and, yet generate cyclic GMP utilizing common CCD machinery.
膜鸟苷酸环化酶家族的原型成员，心房钠尿肽受体鸟苷酸环化酶（ANF-RGC），是两种最具降压作用的激素——心房钠尿肽（ANF）和脑钠肽（BNP）以及细胞内游离钙的生理信号转导器。激素信号和钙调节信号均通过共同的第二信使环磷酸鸟苷（cGMP）起作用；然而，它们的作用模式却有所不同。激素信号通路起始于鸟苷酸环化酶的细胞外结构域；并通过其连续结构域的一系列结构变化激活C端催化结构域（CCD）。相比之下，经由其传感器豆蔻酰化神经钙蛋白δ起作用的钙信号在CCD处起始并直接进行转导。通过详细的序列缺失和表达分析，本研究探讨了信号螺旋结构域（SHD）在这两种转导途径中的作用。SHD是鸟苷酸环化酶中一个保守的由35个氨基酸组成的螺旋区域，由五个七肽组成，每个七肽旨在调节激素信号并将其传递至CCD以进行转导并生成cGMP。其结构为同二聚体，分子对接分析指出螺旋存在反平行排列的可能性。与激素信号传导相反，SHD在钙调节途径的调控中不起作用。这些发现从分子层面确立并定义了ANF-RGC存在两种不同且不重叠的转导模式，并且首次展示了它们的作用方式有多么不同，然而却利用共同的CCD机制生成cGMP。
