title: Tail wags the dog: activity of krait natriuretic peptide is determined by its C-terminal tail in a natriuretic peptide receptor-independent manner.
abstract: Natriuretic peptides (NPs) are potent vasoactive hormones, which maintain pressure-volume homoeostasis. Snake venom NPs exhibit distinct biological activity compared with mammalian NPs due to subtle changes in their sequences. We recently identified a new NP from krait venom (KNP), with an unusual 38-residue long C-terminal tail, which has a propensity to form an α-helix. KNP mediates vasodilation via NP receptor (NPR) independent mechanisms on pre-contracted aortic strips in contrast with classical NPs. The infusion of KNP in anaesthetized rats resulted in a prolonged and sustained drop in blood pressure (BP) and heart rate (HR) with no renal effects in contrast with mammalian counterparts. Deletion mutant studies have revealed the presence of two functional segments in KNP, namely Ring and Helix. Although the Ring interacts with NPR, its contribution to the activity of KNP is shown to be negligible as both KNP and Helix elicit equipotent endothelium-dependent vasorelaxation. Further, KNP and Helix signalled through endothelial nitric oxide (NO) to mediate NPR-independent vasodilation. Thus, KNP exhibits non-canonical characteristics through its C-terminal tail, despite a functional NP ring. The present study has altered the paradigm of NP biology through the understanding of structure-function relationships and may serve as a lead for the design of novel hypotensive agents.
authors.affiliation: Protein Science Laboratory, Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
authors.forename: Sindhuja
authors.initials: S
authors.lastname: Sridharan
authors.affiliation: Protein Science Laboratory, Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Richmond, VA 23298, U.S.A. School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia dbskinim@nus.edu.sg.
authors.forename: R Manjunatha
authors.initials: RM
authors.lastname: Kini
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002038:Bungarotoxins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D008297:Male; D045265:Natriuretic Peptides / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D017433:Protein Structure, Secondary; D051381:Rats; D017207:Rats, Sprague-Dawley; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D002038:Bungarotoxins; D045265:Natriuretic Peptides
keywords: blood pressure; cGMP secondary messenger; endothelium; nitric oxide-dependent vasorelaxation; snake venom