Nitric Oxide Activation of Guanylate Cyclase Pushes the α1 Signaling Helix and the β1 Heme-binding Domain Closer to the Substrate-binding Site

Busker, Mareike; Neidhardt, Inga; Behrends, Sönke

doi:10.1074/jbc.m113.504472

Cited by 21 publications

(23 citation statements)

References 32 publications

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“…The PAS—helical junction may serve as a flexible pivot point for releasing the inhibitory inter-domain contacts. In support of this model, a recent study employing Förster resonance energy transfer revealed NO-induced proximity changes between the sGC H-NOX and catalytic domains (Busker et al, 2013). On the other hand, the possibility that the PAS—helical junction exerts long-range effects through helical domain conformational changes cannot be ruled out (Figure 6B).…”

Section: Discussionmentioning

confidence: 75%

Nitric Oxide-Induced Conformational Changes in Soluble Guanylate Cyclase

et al. 2014

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SUMMARY Soluble guanylate cyclase (sGC) is the primary mediator of nitric oxide (NO) signaling. NO binds the sGC heme cofactor stimulating synthesis of the second messenger cyclic-GMP (cGMP). As the central hub of NO/cGMP signaling pathways, sGC is important in diverse physiological processes such as vasodilation and neurotransmission. Nevertheless, the mechanisms underlying NO-induced cyclase activation in sGC remain unclear. Here, hydrogen/deuterium exchange mass spectrometry (HDX-MS) was employed to probe the NO-induced conformational changes of sGC. HDX-MS revealed NO-induced effects in several discrete regions. NO binding to the heme-NO/O2-binding (H-NOX) domain perturbs a signaling surface implicated in Per/Arnt/Sim (PAS) domain interactions. Furthermore, NO elicits striking conformational changes in the junction between the PAS and helical domains that propagate as perturbations throughout the adjoining helices. Ultimately, NO-binding stimulates the catalytic domain by contracting the active site pocket. Together, these conformational changes delineate an allosteric pathway linking NO-binding to activation of the catalytic domain.

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Section: Discussionmentioning

confidence: 75%

Nitric Oxide-Induced Conformational Changes in Soluble Guanylate Cyclase

et al. 2014

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“…Interestingly, in our maps of both unliganded and NO-bound sGC we observe that the H-NOX domain can make direct contact with the catalytic domain, which could contribute to allosteric control of the catalytic domain by the H-NOX. Busker et al (28) recently proposed a mechanism whereby sGC activation is mediated by both direct interaction between the H-NOX and catalytic domains as well as allosteric interactions through the intervening PAS and helical domains (28). The apparent crucial role of flexible linkers as well as their dynamic fluctuations observed for sGC are common themes among signaling proteins (29).…”

Section: Discussionmentioning

confidence: 99%

Single-particle EM reveals the higher-order domain architecture of soluble guanylate cyclase

Campbell

Underbakke

Potter

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Soluble guanylate cyclase (sGC) is the primary nitric oxide (NO) receptor in mammals and a central component of the NO-signaling pathway. The NO-signaling pathways mediate diverse physiological processes, including vasodilation, neurotransmission, and myocardial functions. sGC is a heterodimer assembled from two homologous subunits, each comprised of four domains. Although crystal structures of isolated domains have been reported, no structure is available for full-length sGC. We used single-particle electron microscopy to obtain the structure of the complete sGC heterodimer and determine its higher-order domain architecture. Overall, the protein is formed of two rigid modules: the catalytic dimer and the clustered Per/Art/Sim and heme-NO/O 2 -binding domains, connected by a parallel coiled coil at two hinge points. The quaternary assembly demonstrates a very high degree of flexibility. We captured hundreds of individual conformational snapshots of free sGC, NO-bound sGC, and guanosine-5′-[(α,β)-methylene]triphosphate-bound sGC. The molecular architecture and pronounced flexibility observed provides a significant step forward in understanding the mechanism of NO signaling.N itric oxide (NO) has emerged as an integral signaling molecule in biology. Soluble guanylate cyclase (sGC), the primary receptor of NO in mammals, binds NO via an Fe II heme cofactor leading to a several hundred-fold increase in 3,5-cyclic guanosine monophosphate (cGMP) synthesis. cGMP then acts as a second messenger, targeting phosphodiesterases, ion-gated channels, and cGMP-dependent protein kinases. These target proteins go on to regulate many critical physiological functions including vasodilation, platelet aggregation, neurotransmission, and myocardial functions (1, 2). Disruptions in NO signaling have been linked to hypertension, erectile dysfunction, neurodegeneration, stroke, and heart disease (3, 4). sGC has been the focus of small-molecule modulators of activity for therapeutic advantage. Riociguat, which is a stimulator of sGC, has recently been approved for treatment of pulmonary hypertension (5). However, the mechanistic details underlying the modulation of sGC catalytic activity by NO and other small molecules remain largely unknown. Determining the structure of the full-length sGC, free and in complex with NO, is therefore a prerequisite to understanding its function and for the design and improvement of therapeutics for treatment of diseases involving the NO/cGMP pathway.The most extensively studied and physiologically relevant isoform of sGC is the 150-kDa heterodimer containing one α1 and one β1 subunit. Each subunit is comprised of four modular domains: the N-terminal heme-NO/O 2 -binding (H-NOX), the Per/Arnt/Sim (PAS), the helical, and the C-terminal catalytic domain (Fig. 1). No structure of the complete holoenzyme is available to date, and its absence precludes answering key questions such as how NO occupancy of the N-terminal β H-NOX sensor domain is communicated to the C-terminal cyclase domain. Atomic models of isola...

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“…Endogenous Trp residues located in βHNOX (Trp22), βGC cat (Trp602), αPAS (Trp352), αCC (Trp466), and αGC cat (Trp669) were used as FRET donors, and MANT-dGTP bound to the catalytic domain was used as a FRET acceptor [99]. While the low quantum yield of Trp residues make them suboptimal FRET partners [100], changes in FRET efficiency were observed in this study.…”

Section: Protein-protein Interactions Regulating Gc-1 Activitymentioning

confidence: 95%

Structure/function of the soluble guanylyl cyclase catalytic domain

Childers

Garcin

2018

Nitric Oxide

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Soluble guanylyl cyclase (GC-1) is the primary receptor of nitric oxide (NO) in smooth muscle cells and maintains vascular function by inducing vasorelaxation in nearby blood vessels. GC-1 converts guanosine 5′-triphosphate (GTP) into cyclic guanosine 3′,5′-monophosphate (cGMP), which acts as a second messenger to improve blood flow. While much work has been done to characterize this pathway, we lack a mechanistic understanding of how NO binding to the heme domain leads to a large increase in activity at the C-terminal catalytic domain. Recent structural evidence and activity measurements from multiple groups have revealed a low-activity cyclase domain that requires additional GC-1 domains to promote a catalytically-competent conformation. How the catalytic domain structurally transitions into the active conformation requires further characterization. This review focuses on structure/function studies of the GC-1 catalytic domain and recent advances various groups have made in understanding how catalytic activity is regulated including small molecules interactions, Cys-S-NO modifications and potential interactions with the NO-sensor domain and other proteins.

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Nitric Oxide Activation of Guanylate Cyclase Pushes the α1 Signaling Helix and the β1 Heme-binding Domain Closer to the Substrate-binding Site

Cited by 21 publications

References 32 publications

Nitric Oxide-Induced Conformational Changes in Soluble Guanylate Cyclase

Nitric Oxide-Induced Conformational Changes in Soluble Guanylate Cyclase

Single-particle EM reveals the higher-order domain architecture of soluble guanylate cyclase

Structure/function of the soluble guanylyl cyclase catalytic domain

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