Volume 16 Supplement 1

Abstracts from the 7th International Conference on cGMP Generators, Effectors and Therapeutic Implications

Open Access

NMR study of a soluble Guanylate Cyclase (sGC) human homologue: the H-NOX domain from Nostoc sp.

  • Aikaterini Argyriou1,
  • Marina Bantzi2,
  • Athanassios Giannis2,
  • Andreas Papapetropoulos1, 3Email author and
  • Georgios A Spyroulias1
BMC Pharmacology and Toxicology201516(Suppl 1):A73

DOI: 10.1186/2050-6511-16-S1-A73

Published: 2 September 2015

Heme-nitric oxide/oxygen binding (H-NOX) motifs can be found as proteins of approximately 200 amino acids in length or can exist as a domain within larger proteins, such as soluble guanylate cyclase. The H-NOX domain is conserved across eukaryotes and bacteria; within sGC, the H-NOX domain functions as a sensor for the gaseous signaling agent nitric oxide (NO). Soluble guanylate cyclase (sGC) contains a heme-binding N-terminal domain that regulates the catalytic site contained within the C-terminal end of the enzyme. sGC is a heterodimer, consisting of α1 or α2 subunit bound to β1 and catalyzes the conversion of GTP to GMP. Activation of NO by sGC increases its activity several hundred-fold, promoting vasodilation and inhibiting platelet aggregation. Under pathophysiological conditions characterized by oxidative stress, sGC suffers heme loss, becomes unresponsive to NO and is tagged for degradation by the ubiquitin-proteasome pathway, leading to compromised NO signaling and cardiovascular disease. Ligands, such as BAY 58-2667, activate sGC in a heme-independent manner and protect heme-oxidized sGC from proteasome degradation. Herein, we present a preliminary NMR investigation of the conformational and electronic properties of the heme-bound H-NOX protein from Nostoc sp., which shares a 35% sequence identity with the H-NOX domain of human sGC. Additionally, we use UV-visible and heteronuclear NMR spectroscopy in order to investigate the structural integrity, the conformational variations and the dynamics of the H-NOX polypeptide during oxidation of the Fe(II) ion, while data on the changes/destabilization of the heme moiety upon the addition of a number of ligands and oxidizing agents (NO, BAY 58-2667, ODQ) are acquired through NMR. Monitoring the dynamical behavior of the H-NOX domain and the alterations occurring in its structure triggered by the changes in the oxidation status of the Fe(II)-Protporphyrin IX prosthetic group in solution by NMR, may provide valuable insights for sGC activation/stimulation and NO signaling.



We acknowledge partial support from EU FP7-REGPOT-2011 “SEE-DRUG” (nr. 285950 to A.P. & G.S.).

Authors’ Affiliations

Department of Pharmacy, University of Patras
Institute of Organic Chemistry, Leipzig University
School of Health Sciences, Faculty of Pharmacy, University of Athens


© Argyriou et al. 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.