Phosphodiesterases Catalyze Hydrolysis of cAMP-bound to Regulatory Subunit of Protein Kinase A and Mediate Signal Termination

Moorthy, Balakrishnan S.; Gao, Yue; Anand, Ganesh S.

doi:10.1074/mcp.m110.002295

Cited by 35 publications

(63 citation statements)

References 51 publications

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“…Recently, Anand and coworkers (37,38) reported that phosphodiesterases (PDEs) can bind to and catalyze cAMP release from PKA RIα. The ligands are channeled from the tandem CBDs to the active sites of a PDE dimer and then hydrolyzed.…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, the other subunit in the PDE dimer can now bind to CBD-B. In the meantime, the C subunit enters the space created between the two domains and displaces the PDE dimer as soon as the B-site cAMP completes channeling (37). Finally, the relative orientation and position of the two domains in the R subunit are further changed around the C subunit to form a stable complex.…”

Section: Discussionmentioning

confidence: 99%

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Unidirectional allostery in the regulatory subunit RIα facilitates efficient deactivation of protein kinase A

Guo

Zhou

2016

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

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The holoenzyme complex of protein kinase A is in an inactive state; activation involves ordered cAMP binding to two tandem domains of the regulatory subunit and release of the catalytic subunit. Deactivation has been less studied, during which the two cAMPs unbind from the regulatory subunit to allow association of the catalytic subunit to reform the holoenzyme complex. Unbinding of the cAMPs appears ordered as indicated by a large difference in unbinding rates from the two sites, but the cause has remained elusive given the structural similarity of the two tandem domains. Even more intriguingly, NMR data show that allosteric communication between the two domains is unidirectional. Here, we present a mechanism for the unidirectionality, developed from extensive molecular dynamics simulations of the tandem domains in different cAMP-bound forms. Disparate responses to cAMP releases from the two sites (A and B) in conformational flexibility and chemical shift perturbation confirmed unidirectional allosteric communication. Community analysis revealed that the A-site cAMP, by forming across-domain interactions, bridges an essential pathway for interdomain communication. The pathway is impaired when this cAMP is removed but remains intact when only the B-site cAMP is removed. Specifically, removal of the A-site cAMP leads to the separation of the two domains, creating room for binding the catalytic subunit. Moreover, the A-site cAMP, by maintaining interdomain coupling, retards the unbinding of the B-site cAMP and stalls an unproductive pathway of cAMP release. Our work expands the perspective on allostery and implicates functional importance for the directionality of allostery.unidirectional allostery | cAMP | molecular dynamics | community analysis | NMR spectroscopy P rotein kinase A (PKA), also known as cAMP-dependent protein kinase, plays an important role in multiple cellular processes by catalyzing protein phosphorylation (1). Its dysregulation is involved in many diseases including cancer and inflammatory disorders (2). The holoenzyme complex, formed by two catalytic (C) subunits bound to a homodimer of regulatory (R) subunits, is inactive. Each regulatory subunit contains two tandem cAMP-binding domains (referred to as CBD-A and CBD-B) (3); in the holoenzyme complex, the A site is masked by the C subunit (4). Activation occurs when two cAMP molecules bind sequentially and cooperatively to the two sites on each R subunit (5). Possible structural changes in the activation process have been constructed from crystallographic studies (4). The first cAMP molecule binds to the B site and makes the A site accessible. Binding of the second cAMP molecule then leads to the release of the C subunit for catalyzing substrate phosphorylation. Deactivation, involving the unbinding of the two cAMP molecules from an R subunit and association of the R and C subunits to reform the holoenzyme complex, has been less studied, and a number of important questions remain open. In particular, kinetic studies have shown that the cAMP un...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Unidirectional allostery in the regulatory subunit RIα facilitates efficient deactivation of protein kinase A

Guo

Zhou

2016

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

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“…Finally, recent work has highlighted the role direct binding between protein kinase A-anchoring proteins and phosphodiesterases plays in PKA activation in vivo (32,33). Therefore, the current model, which is based on in vitro data, cannot fully capture in vivo activity.…”

Section: Discussionmentioning

confidence: 99%

Using Markov State Models to Develop a Mechanistic Understanding of Protein Kinase A Regulatory Subunit RIα Activation in Response to cAMP Binding

Boras

Kornev²,

Taylor

et al. 2014

Journal of Biological Chemistry

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Background: Binding four cAMP molecules activates protein kinase A (PKA). Results: Mechanistic Markov models (MM) show that although one cAMP activates one catalytic subunit four are necessary for full activation. Conclusion: Conformational selection is the predominant mechanism in PKA activation, but heterodimer interactions are also required. Significance: This MM provides a mechanistic foundation for systems models of PKA signaling networks.

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“…Our results showed that the inhibition of PKA by Rp-cAMPS blocked the enhancing effect of NE on the persistence of extinction LTM and activation of the b-receptor-dependent PKA/CREB signaling pathway induced by NE. The cAMP analog Rp-cAMPs might also affect the activity of other cAMP substrates, including cyclic nucleotide-gated ion channels and cAMP hydrolases and cyclic nucleotide phosphodiesterases, two groups of molecules that interact with PKA (Moorthy et al, 2011;Rochais et al, 2004). Nevertheless, in the present study, we showed that the phosphorylation levels of both PKA and GluR1 (Ser 845, a site phosphorylated by PKA) were inhibited by Rp-cAMPs, suggesting that PKA is at least one of the main molecules that mediate the effect of NE on the persistence of extinction LTM.…”

Section: Mechanism That Underlies the Role Of Hippocampal Ne In The Pmentioning

confidence: 99%

Delayed Noradrenergic Activation in the Dorsal Hippocampus Promotes the Long-Term Persistence of Extinguished Fear

Chai

Liu

Xue

et al. 2014

Neuropsychopharmacol

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Fear extinction has been extensively studied, but little is known about the molecular processes that underlie the persistence of extinction long-term memory (LTM). We found that microinfusion of norepinephrine (NE) into the CA1 area of the dorsal hippocampus during the early phase (0 h) after extinction enhanced extinction LTM at 2 and 14 days after extinction. Intra-CA1 infusion of NE during the late phase (12 h) after extinction selectively promoted extinction LTM at 14 days after extinction that was blocked by the b-receptor antagonist propranolol, protein kinase A (PKA) inhibitor Rp-cAMPS, and protein synthesis inhibitors anisomycin and emetine. The phosphorylation levels of PKA, cyclic adenosine monophosphate response element-binding protein (CREB), GluR1, and the membrane GluR1 level were increased by NE during the late phase after extinction that was also blocked by propranolol and Rp-cAMPS. These results suggest that the enhancement of extinction LTM persistence induced by NE requires the activation of the b-receptor/PKA/CREB signaling pathway and membrane GluR1 trafficking. Moreover, extinction increased the phosphorylation levels of Erk1/2, CREB, and GluR1, and the membrane GluR1 level during the late phase, and anisomycin/emetine alone disrupted the persistence of extinction LTM, indicating that the persistence of extinction LTM requires late-phase protein synthesis in the CA1. Propranolol and Rp-cAMPS did not completely disrupt the persistence of extinction LTM, suggesting that another b-receptor/PKA-independent mechanism underlies the persistence of extinction LTM. Altogether, our results showed that enhancing hippocampal noradrenergic activity during the late phase after extinction selectively promotes the persistence of extinction LTM.

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Phosphodiesterases Catalyze Hydrolysis of cAMP-bound to Regulatory Subunit of Protein Kinase A and Mediate Signal Termination

Cited by 35 publications

References 51 publications

Unidirectional allostery in the regulatory subunit RIα facilitates efficient deactivation of protein kinase A

Unidirectional allostery in the regulatory subunit RIα facilitates efficient deactivation of protein kinase A

Using Markov State Models to Develop a Mechanistic Understanding of Protein Kinase A Regulatory Subunit RIα Activation in Response to cAMP Binding

Delayed Noradrenergic Activation in the Dorsal Hippocampus Promotes the Long-Term Persistence of Extinguished Fear

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