Allosteric Modification, the Primary ATP Activation Mechanism of Atrial Natriuretic Factor Receptor Guanylate Cyclase

Abstract

ANF-RGC is the prototype receptor membrane guanylate cyclase being both the receptor and the signal transducer of the most hypotensive hormones, ANF and BNP. It is a single transmembrane-spanning protein. After binding these hormones at the extracellular domain it at its intracellular domain signals activation of the C-terminal catalytic module and accelerates the production of its second messenger, cyclic GMP, which controls blood pressure, cardiac vasculature and fluid secretion. ATP is obligatory for the post-transmembrane dynamic events leading to ANF-RGC activation. It functions through the ATP regulated module, ARM (KHD) domain, of ANF-RGC. In the current over-a-decade-held-model “phosphorylation of the KHD is absolutely required for hormone-dependent activation of NPR-A” (Potter, L.R., and T. Hunter. 1998. Mol. Cell. Biol. 18: 2164–2172). The presented study challenges this concept. It demonstrates that, instead, ATP allosteric modification of ARM is the primary signaling step of ANF-GC activation. In this 2-step new dynamic model, ATP in the first step binds ARM. This triggers in it a chain of transduction events, which cause its allosteric modification. The modification partially activates (about 50%) ANF-RGC; and concomitantly also prepares the ARM for the second successive step. In this second step, ARM is phosphorylated and ANF-RGC achieves additional (~50%) full catalytic activation. The study defines a new paradigm of ANF-RGC signaling mechanism.

ATP Potentiates Competitive Inhibition of Guanylyl Cyclase A and B by the Staurosporine Analog, Gö6976

“…We do not know why our results are the opposite of those recently published by Duda et al (20,21). However, one major difference is that GTP concentrations were 1 mM in our assay but 0.1 mM in their assay.…”

“…Staurosporine Derivatives Do Not Activate GC-A or GC-BTwo recent studies suggest that staurosporine effectively substitutes for ATP in the activation of GC-A (20,21). Therefore, we tested the ability of Gö6976 and the related compound, staurosporine, to activate GC-A and GC-B (Fig.…”

The ANF-RGC Gene Motif 669WTAPELL675 Is Vital for Blood Pressure Regulation: Biochemical Mechanism

“…ANF-dependent cyclic GMP is generated and it functions as the second messenger of blood pressure regulation. Concomitantly, phosphorylation converts the ATP binding site from high to low affinity, ATP dissociates, and ANF-RGC returns to its ground state 55 . (ii) Post cyclic GMP production events .…”

Guanylyl Cyclases A and B Are Asymmetric Dimers That Are Allosterically Activated by ATP Binding to the Catalytic Domain

“…Early kinetic assays indicating that ATP increases maximal velocity together with the identification of a putative GXGXXXG ATP-binding motif in the KHD led to a model in which NP binding to the extracellular domain was proposed to stimulate the binding of ATP to the KHD (Fig. 6) (30, 42, 43). Two studies demonstrating cross-linking of azido-ATP analogs to the KHD of GC-A provide some support for this model, although the azido analog used in one study inhibited GC-A and the other study did not test the effects of the azido analog on enzyme activity (26, 31).…”