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

2016 ◽  
Vol 113 (44) ◽  
pp. E6776-E6785 ◽  
Author(s):  
Cong Guo ◽  
Huan-Xiang Zhou
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Structural Similarity ◽  
Community Analysis ◽  
Catalytic Subunit ◽  
Regulatory Subunit ◽  
Allosteric Communication ◽  
Dynamics Simulations ◽  
A Site ◽  
Kinase A

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.

scholarly journals Candida albicans Lacking the Gene Encoding the Regulatory Subunit of Protein Kinase A Displays a Defect in Hyphal Formation and an Altered Localization of the Catalytic Subunit

2004 ◽  
Vol 3 (1) ◽  
pp. 190-199 ◽  
Author(s):  
Alejandro Cassola ◽  
Marc Parrot ◽  
Susana Silberstein ◽  
Beatrice B. Magee ◽  
Susana Passeron ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Protein Kinase ◽  
Fusion Protein ◽  
Protein Kinase A ◽  
Double Mutant ◽  
Catalytic Subunit ◽  
Regulatory Subunit ◽  
Wild Type ◽  
Gfp Fusion Protein ◽  
Kinase A

ABSTRACT The fungal pathogen Candida albicans switches from a yeast-like to a filamentous mode of growth in response to a variety of environmental conditions. We examined the morphogenetic behavior of C. albicans yeast cells lacking the BCY1 gene, which encodes the regulatory subunit of protein kinase A. We cloned the BCY1 gene and generated a bcy1 tpk2 double mutant strain because a homozygous bcy1 mutant in a wild-type genetic background could not be obtained. In the bcy1 tpk2 mutant, protein kinase A activity (due to the presence of the TPK1 gene) was cyclic AMP independent, indicating that the cells harbored an unregulated phosphotransferase activity. This mutant has constitutive protein kinase A activity and displayed a defective germinative phenotype in N-acetylglucosamine and in serum-containing medium. The subcellular localization of a Tpk1-green fluorescent protein (GFP) fusion protein was examined in wild-type, tpk2 null, and bcy1 tpk2 double mutant strains. The fusion protein was observed to be predominantly nuclear in wild-type and tpk2 strains. This was not the case in the bcy1 tpk2 double mutant, where it appeared dispersed throughout the cell. Coimmunoprecipitation of Bcy1p with the Tpk1-GFP fusion protein demonstrated the interaction of these proteins inside the cell. These results suggest that one of the roles of Bcy1p is to tether the protein kinase A catalytic subunit to the nucleus.

A novel activating effect of the regulatory subunit of protein kinase A on catalytic subunit activity

2008 ◽  
Vol 480 (2) ◽  
pp. 95-103 ◽  
Author(s):  
Jimena Rinaldi ◽  
Josefina Ocampo ◽  
Silvia Rossi ◽  
Silvia Moreno
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Catalytic Subunit ◽  
Regulatory Subunit ◽  
Kinase A

scholarly journals Protein kinase A activation: Something new under the sun?

2018 ◽  
Vol 217 (6) ◽  
pp. 1895-1897 ◽  
Author(s):  
F. Donelson Smith ◽  
John D. Scott
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Active Site ◽  
Catalytic Subunit ◽  
Regulatory Subunit ◽  
The Sun ◽  
Type Ii ◽  
Activation Mechanisms ◽  
Kinase A

The role of autophosphorylation of the type II regulatory subunit in activation of protein kinase A (PKA) has been a longstanding question. In this issue, Isensee et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201708053) use antibody tools that selectively recognize phosphorylated RII and the catalytic subunit active site to reexamine PKA holoenzyme activation mechanisms in neurons.

scholarly journals Allosteric pluripotency as revealed by protein kinase A

2020 ◽  
Vol 6 (25) ◽  
pp. eabb1250 ◽  
Author(s):  
J. A. Byun ◽  
M. Akimoto ◽  
B. VanSchouwen ◽  
T. S. Lazarou ◽  
S. S. Taylor ◽  
...  
Keyword(s):  
Free Energy ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Regulatory Subunit ◽  
Resonance Spectroscopy ◽  
Threshold Values ◽  
Activation Threshold ◽  
Domain Interactions ◽  
Dynamics Simulations ◽  
Kinase A

The functional response of a signaling system to an allosteric stimulus often depends on subcellular conditions, a phenomenon known as pluripotent allostery. For example, a single allosteric modulator, Rp-cAMPS, of the prototypical protein kinase A (PKA) switches from antagonist to agonist depending on MgATP levels. However, the mechanism underlying such pluripotent allostery has remained elusive for decades. Using nuclear magnetic resonance spectroscopy, ensemble models, kinase assays, and molecular dynamics simulations, we show that allosteric pluripotency arises from surprisingly divergent responses of highly homologous tandem domains. The differential responses perturb domain-domain interactions and remodel the free-energy landscape of inhibitory excited states sampled by the regulatory subunit of PKA. The resulting activation threshold values are comparable to the effective free energy of regulatory and catalytic subunit binding, which depends on metabolites, substrates, and mutations, explaining pluripotent allostery and warranting a general redefinition of allosteric targets to include specific subcellular environments.

scholarly journals Targeting the Regulatory Subunit R2Alpha of Protein Kinase A in Human Glioblastoma through shRNA-Expressing Lentiviral Vectors

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1361
Author(s):  
Maira Zorzan ◽  
Claudia Del Vecchio ◽  
Stefania Vogiatzis ◽  
Elisa Saccon ◽  
Cristina Parolin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Lentiviral Vectors ◽  
Brain Parenchyma ◽  
Regulatory Subunit ◽  
Glioblastoma Cells ◽  
Cellular Models ◽  
Therapeutic Setting ◽  
Promising Target ◽  
Kinase A

Glioblastoma is the most malignant and most common form of brain tumor, still today associated with a poor 14-months median survival from diagnosis. Protein kinase A, particularly its regulatory subunit R2Alpha, presents a typical intracellular distribution in glioblastoma cells compared to the healthy brain parenchyma and this peculiarity might be exploited in a therapeutic setting. In the present study, a third-generation lentiviral system for delivery of shRNA targeting the regulatory subunit R2Alpha of protein kinase A was developed. Generated lentiviral vectors are able to induce an efficient and stable downregulation of R2Alpha in different cellular models, including non-stem and stem-like glioblastoma cells. In addition, our data suggest a potential correlation between silencing of the regulatory subunit of protein kinase A and reduced viability of tumor cells, apparently due to a reduction in replication rate. Thus, our findings support the role of protein kinase A as a promising target for novel anti-glioma therapies.

The crystal structure of yeast regulatory subunit reveals key evolutionary insights into Protein Kinase A oligomerization

2021 ◽  
pp. 107732
Author(s):  
Nicolás González Bardeci ◽  
Enzo Tofolón ◽  
Felipe Trajtenberg ◽  
Julio Caramelo ◽  
Nicole Larrieux ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Regulatory Subunit ◽  
Kinase A
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