Atrial natriuretic factor receptor guanylate cyclase signaling: new ATP-regulated transduction motif

Abstract

ANF-RGC$ membrane guanylate cyclase is the receptor for the hypotensive peptide hormones, atrial natriuretic factor (ANF) and type B natriuretic peptide (BNP). It is a single transmembrane spanning protein. Binding the hormone to the extracellular domain activates its intracellular catalytic domain. This results in accelerated production of cyclic GMP, a second messenger in controlling blood pressure, cardiac vasculature and fluid secretion. ATP is the obligatory transducer of the ANF signal. It works through its ATP regulated module, ARM, which is juxtaposed to the C-terminal side of the transmembrane domain. Upon interaction, ATP induces a cascade of temporal and spatial changes in the ARM, which, finally, result in activation of the catalytic module. Although the exact nature and the details of these changes are not known, some of these have been stereographed in the simulated three-dimensional model of the ARM and validated biochemically. Through comprehensive techniques ofsteady-state, time-resolved tryptophan fluorescence and Forster Resonance Energy Transfer (FRET), site-directed and deletion-mutagenesis, and reconstitution, the present study validates and explains themechanism of the model-based predicted transduction role of the ARM's structural motif, 669 WTAPELL 675 . This motif is critical in the ATP-dependent ANF signaling. Molecular modeling shows that ATP binding exposes the 669 WTAPELL 675 motif, the exposure, in turn, facilitates its interaction and activation of the catalytic module. These principles of the model have been experimentally validated. This knowledge brings us a step closer to our understanding of the mechanism by which the ATP-dependent spatial changes within the ARM cause ANF signaling of ANF-RGC.

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

“…The model represents one ATP binding site within the ARM domain monomer what is consistent with the existing biochemical data (39, 49). The analysis of the ARM domain model was focused on the six serine and threonine residues, the Grc motif, and their surroundings.…”

“…The signal twists the transmembrane domain (38), induces a structural change in the ARM domain, and prepares it for the ATP activation (42). Step 1, ARM domain binds ATP to its pocket what leads to a cascade of temporal and spatial changes (32, 39, 41–43). They involve (1) shift in ATP binding pocket position by 3 to 4Å; and rotation of its floor by 15º.…”

657WTAPELL663 motif of the photoreceptor ROS-GC1: A general phototransduction switch

“…Cued by the findings on the signaling mechanism of the prototype membrane guanylate cyclase ANF-RGC [25], the presented study demonstrates that the 657 WTAPELL 663 motif of the photoreceptor ROS-GC1 is also vital for its regulatory activity. This finding has a Core Impact on the membrane guanylate cyclase field; and illuminates a basic principle of the Phototransduction machinery by which it controls different shades of the LIGHT signal.…”

“…Based on the ANF-RGC signaling template that the WTAPELL motif is critical for its regulatory catalytic activity [25] and the fact that this motif is conserved in all membrane guanylate cyclases, the question was raised: would the 657 WTAPELL 663 motif be also critical in ROS-GC1 signaling? What follows is the systematic analysis of this issue.…”

ATP allosteric activation of atrial natriuretic factor receptor guanylate cyclase

“…Most significantly, the ATP signaling of ANF‐RGC has been demonstrated through direct binding of 8‐azido‐ATP [27,28]. In addition, systematic analyses involving steady‐state, time‐resolved tryptophan fluorescence and Förster resonance energy transfer (FRET), site‐directed and deletion mutagenesis techniques, as well as reconstitution and molecular modeling studies, have validated the basic operational principles of the model and revealed many of its structural elements [29]. The ATP‐binding ARM domain of ANF‐RGC has two distinct structural elements.…”