Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis
Acrodysostosis represents a group of rare genetic disorders characterized by defective skeletal development and is often accompanied by intellectual disabilities. Mutations in the 3′5′cyclic AMP (cAMP)-dependent protein kinase (PKA) type I regulatory subunit isoform α (RIα) and phosphodiesterase (PD...
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Frontiers Media S.A.
2023-09-01
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| Series: | Frontiers in Molecular Biosciences |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmolb.2023.1202268/full |
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| author | Varun Venkatakrishnan Abhijeet Ghode Nikhil K. Tulsian Ganesh S. Anand Ganesh S. Anand |
| author_facet | Varun Venkatakrishnan Abhijeet Ghode Nikhil K. Tulsian Ganesh S. Anand Ganesh S. Anand |
| author_sort | Varun Venkatakrishnan |
| collection | DOAJ |
| description | Acrodysostosis represents a group of rare genetic disorders characterized by defective skeletal development and is often accompanied by intellectual disabilities. Mutations in the 3′5′cyclic AMP (cAMP)-dependent protein kinase (PKA) type I regulatory subunit isoform α (RIα) and phosphodiesterase (PDE) PDE4D have both been implicated in impaired PKA regulation in acrodysostosis. How mutations on PDEs and RIα interfere with the regulation of cAMP-PKA signaling is not understood. cAMP-PKA signaling can be described in two phases. In the activation phase, cAMP binding to RIα dissociates the free C-subunit (Catalytic subunit). PDEs hydrolyze cAMP bound to RIα, priming the cAMP-free RIα for reassociation with the C-subunit, thereby completing one PKA activation cycle. Signal termination is thus critical for resetting PKA to its basal state and promoting adaptation to hormonal hyperstimulation. This proceeds through formation of a transient signal termination RIα: PDE complex that facilitates cAMP channeling from the cAMP-binding domain of RIα to the catalytic site of PDE. Signal termination of cAMP-PKA proceeds in three steps: Step 1) Channeling: translocation of cAMP from the CNB of RIα to the PDE catalytic site for hydrolysis. Step 2) Processivity: binding of free cAMP from the cytosol at both CNBs of RIα. Step 3) Product (5′AMP) release from the PDE hydrolysis site through competitive displacement by a new molecule of cAMP that triggers subsequent activation cycles of PKA. We have identified the molecular basis for two acrodysostosis mutants, PDE (PDE8 T690P) and RIα (T207A), that both allosterically impair cAMP-PKA signal termination. A combination of amide hydrogen/deuterium exchange mass spectrometry (HDXMS) and fluorescence polarization (FP) reveals that PDE8 T690P and RIα T207A both blocked processive hydrolysis of cAMP by interfering with competitive displacement of product 5′AMP release from the nucleotide channel at the end of each round of cAMP hydrolysis. While T690P blocked product 5′AMP release from the PDE, T207A greatly slowed the release of the substrate from RIα. These results highlight the role of processivity in cAMP hydrolysis by RIα: PDE termination complexes for adaptation to cAMP from GPCR hyperstimulation. Impairment of the signal termination process provides an alternate molecular basis for acrodysostosis. |
| first_indexed | 2024-03-11T22:54:34Z |
| format | Article |
| id | doaj.art-5116d8c96920407f986b9c68570756ed |
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| language | English |
| last_indexed | 2024-03-11T22:54:34Z |
| publishDate | 2023-09-01 |
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| spelling | doaj.art-5116d8c96920407f986b9c68570756ed2023-09-21T18:39:55ZengFrontiers Media S.A.Frontiers in Molecular Biosciences2296-889X2023-09-011010.3389/fmolb.2023.12022681202268Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosisVarun Venkatakrishnan0Abhijeet Ghode1Nikhil K. Tulsian2Ganesh S. Anand3Ganesh S. Anand4Department of Chemistry, Pennsylvania State University, University Park, PA, United StatesDepartment of Biological Sciences, National University of Singapore, Singapore, SingaporeDepartment of Biological Sciences, National University of Singapore, Singapore, SingaporeDepartment of Chemistry, Pennsylvania State University, University Park, PA, United StatesThe Huck Institutes of the life sciences, Pennsylvania State University, University Park, PA, United StatesAcrodysostosis represents a group of rare genetic disorders characterized by defective skeletal development and is often accompanied by intellectual disabilities. Mutations in the 3′5′cyclic AMP (cAMP)-dependent protein kinase (PKA) type I regulatory subunit isoform α (RIα) and phosphodiesterase (PDE) PDE4D have both been implicated in impaired PKA regulation in acrodysostosis. How mutations on PDEs and RIα interfere with the regulation of cAMP-PKA signaling is not understood. cAMP-PKA signaling can be described in two phases. In the activation phase, cAMP binding to RIα dissociates the free C-subunit (Catalytic subunit). PDEs hydrolyze cAMP bound to RIα, priming the cAMP-free RIα for reassociation with the C-subunit, thereby completing one PKA activation cycle. Signal termination is thus critical for resetting PKA to its basal state and promoting adaptation to hormonal hyperstimulation. This proceeds through formation of a transient signal termination RIα: PDE complex that facilitates cAMP channeling from the cAMP-binding domain of RIα to the catalytic site of PDE. Signal termination of cAMP-PKA proceeds in three steps: Step 1) Channeling: translocation of cAMP from the CNB of RIα to the PDE catalytic site for hydrolysis. Step 2) Processivity: binding of free cAMP from the cytosol at both CNBs of RIα. Step 3) Product (5′AMP) release from the PDE hydrolysis site through competitive displacement by a new molecule of cAMP that triggers subsequent activation cycles of PKA. We have identified the molecular basis for two acrodysostosis mutants, PDE (PDE8 T690P) and RIα (T207A), that both allosterically impair cAMP-PKA signal termination. A combination of amide hydrogen/deuterium exchange mass spectrometry (HDXMS) and fluorescence polarization (FP) reveals that PDE8 T690P and RIα T207A both blocked processive hydrolysis of cAMP by interfering with competitive displacement of product 5′AMP release from the nucleotide channel at the end of each round of cAMP hydrolysis. While T690P blocked product 5′AMP release from the PDE, T207A greatly slowed the release of the substrate from RIα. These results highlight the role of processivity in cAMP hydrolysis by RIα: PDE termination complexes for adaptation to cAMP from GPCR hyperstimulation. Impairment of the signal termination process provides an alternate molecular basis for acrodysostosis.https://www.frontiersin.org/articles/10.3389/fmolb.2023.1202268/fullacrodysostosisprotein kinase ARIαphosphodiesterasesignal terminationallostery |
| spellingShingle | Varun Venkatakrishnan Abhijeet Ghode Nikhil K. Tulsian Ganesh S. Anand Ganesh S. Anand Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis Frontiers in Molecular Biosciences acrodysostosis protein kinase A RIα phosphodiesterase signal termination allostery |
| title | Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis |
| title_full | Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis |
| title_fullStr | Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis |
| title_full_unstemmed | Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis |
| title_short | Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis |
| title_sort | impaired camp processivity by phosphodiesterase protein kinase a complexes in acrodysostosis |
| topic | acrodysostosis protein kinase A RIα phosphodiesterase signal termination allostery |
| url | https://www.frontiersin.org/articles/10.3389/fmolb.2023.1202268/full |
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