Structural insight into hormone recognition by the natriuretic peptide receptor-A.

Atrial natriuretic peptide (ANP) plays a central role in the regulation of blood pressure and volume. ANP activities are mediated by natriuretic peptide receptor-A (NPR-A), a single-pass transmembrane receptor harboring intrinsic guanylate cyclase activity. This study investigated the mechanism underlying NPR-A-dependent hormone recognition through the determination of the crystal structures of the NPR-A extracellular hormone-binding domain complexed with full-length ANP, truncated mutants of ANP, and dendroaspis natriuretic peptide (DNP) isolated from the venom of the green Mamba snake, Dendroaspis angusticeps. The bound peptides possessed pseudo-two-fold symmetry, despite the lack of two-fold symmetry in the primary sequences, which enabled the tight coupling of the peptide to the receptor, and evidently contributes to guanylyl cyclase activity. The binding of DNP to the NPR-A was essentially identical to that of ANP; however, the affinity of DNP for NPR-A was higher than that of ANP owing to the additional interactions between distinctive sequences in the DNP and NPR-A. Consequently, our findings provide valuable insights that can be applied to the development of novel agonists for the treatment of various human diseases.