Dataset Information

Probing the Structural Dynamics of the Catalytic Domain of Human Soluble Guanylate Cyclase.

ABSTRACT: In the nitric oxide (NO) signaling pathway, human soluble guanylate cyclase (hsGC) synthesizes cyclic guanosine monophosphate (cGMP); responsible for the regulation of cGMP-specific protein kinases (PKGs) and phosphodiesterases (PDEs). The crystal structure of the inactive hsGC cyclase dimer is known, but there is still a lack of information regarding the substrate-specific internal motions that are essential for the catalytic mechanism of the hsGC. In the current study, the hsGC cyclase heterodimer complexed with guanosine triphosphate (GTP) and cGMP was subjected to molecular dynamics simulations, to investigate the conformational dynamics that have functional implications on the catalytic activity of hsGC. Results revealed that in the GTP-bound complex of the hsGC heterodimer, helix 1 of subunit ? (?:h1) moves slightly inwards and comes close to helix 4 of subunit ? (?:h4). This conformational change brings loop 2 of subunit ? (?:L2) closer to helix 2 of subunit ? (?:h2). Likewise, loop 2 of subunit ? (?:L2) comes closer to helix 2 of subunit ? (?:h2). These structural events stabilize and lock GTP within the closed pocket for cyclization. In the cGMP-bound complex, ?:L2 detaches from ?:h2 and establishes interactions with ?:L2, which results in the loss of global structure compactness. Furthermore, with the release of pyrophosphate, the interaction between ?:h1 and ?:L2 weakens, abolishing the tight packing of the binding pocket. This study discusses the conformational changes induced by the binding of GTP and cGMP to the hsGC catalytic domain, valuable in designing new therapeutic strategies for the treatment of cardiovascular diseases.

SUBMITTER: Khalid RR

PROVIDER: S-EPMC7289801 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Probing the Structural Dynamics of the Catalytic Domain of Human Soluble Guanylate Cyclase.

Khalid Rana Rehan RR Maryam Arooma A Sezerman Osman Ugur OU Mylonas Efstratios E Siddiqi Abdul Rauf AR Kokkinidis Michael M

Scientific reports 20200611 1

In the nitric oxide (NO) signaling pathway, human soluble guanylate cyclase (hsGC) synthesizes cyclic guanosine monophosphate (cGMP); responsible for the regulation of cGMP-specific protein kinases (PKGs) and phosphodiesterases (PDEs). The crystal structure of the inactive hsGC cyclase dimer is known, but there is still a lack of information regarding the substrate-specific internal motions that are essential for the catalytic mechanism of the hsGC. In the current study, the hsGC cyclase heterod ...[more]

PMID: 32528025

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Project description:Eukaryotic nitric oxide (NO) signaling involves modulation of cyclic GMP (cGMP) levels through activation of the soluble isoform of guanylate cyclase (sGC). sGC is a heterodimeric hemoprotein that contains a Heme-Nitric oxide and OXygen binding (H-NOX) domain, a Per/ARNT/Sim (PAS) domain, a coiled-coil (CC) domain, and a catalytic domain. To evaluate the role of these domains in regulating the ligand binding properties of the heme cofactor of NO-sensitive sGC, we constructed chimeras by swapping the rat β1 H-NOX domain with the homologous region of H-NOX domain-containing proteins from Thermoanaerobacter tengcongensis, Vibrio cholerae, and Caenorhabditis elegans (TtTar4H, VCA0720, and Gcy-33, respectively). Characterization of ligand binding by electronic absorption and resonance Raman spectroscopy indicates that the other rat sGC domains influence the bacterial and worm H-NOX domains. Analysis of cGMP production in these proteins reveals that the chimeras containing bacterial H-NOX domains exhibit guanylate cyclase activity, but this activity is not influenced by gaseous ligand binding to the heme cofactor. The rat-worm chimera containing the atypical sGC Gcy-33 H-NOX domain was weakly activated by NO, CO, and O(2), suggesting that atypical guanylate cyclases and NO-sensitive guanylate cyclases have a common molecular mechanism for enzyme activation. To probe the influence of the other sGC domains on the mammalian sGC heme environment, we generated heme pocket mutants (Pro118Ala and Ile145Tyr) in the β1 H-NOX construct (residues 1-194), the β1 H-NOX-PAS-CC construct (residues 1-385), and the full-length α1β1 sGC heterodimer (β1 residues 1-619). Spectroscopic characterization of these proteins shows that interdomain communication modulates the coordination state of the heme-NO complex and the heme oxidation rate. Taken together, these findings have important implications for the allosteric mechanism of regulation within H-NOX domain-containing proteins.

Dataset Information

Probing the Structural Dynamics of the Catalytic Domain of Human Soluble Guanylate Cyclase.

Publications

Probing the Structural Dynamics of the Catalytic Domain of Human Soluble Guanylate Cyclase.

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