Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme.
To provide tight spatiotemporal signaling control, the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) holoenzyme typically nucleates a macromolecular complex or a "PKA signalosome." Using the RIIβ holoenzyme as a prototype, we show how autophosphorylation/dephosphoryl...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2015-07-01
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| Series: | PLoS Biology |
| Online Access: | https://doi.org/10.1371/journal.pbio.1002192 |
| _version_ | 1818578186780278784 |
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| author | Ping Zhang Matthias J Knape Lalima G Ahuja Malik M Keshwani Charles C King Mira Sastri Friedrich W Herberg Susan S Taylor |
| author_facet | Ping Zhang Matthias J Knape Lalima G Ahuja Malik M Keshwani Charles C King Mira Sastri Friedrich W Herberg Susan S Taylor |
| author_sort | Ping Zhang |
| collection | DOAJ |
| description | To provide tight spatiotemporal signaling control, the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) holoenzyme typically nucleates a macromolecular complex or a "PKA signalosome." Using the RIIβ holoenzyme as a prototype, we show how autophosphorylation/dephosphorylation of the RIIβ subunit, as well as cAMP and metal ions, contribute to the dynamics of PKA signaling. While we showed previously that the RIIβ holoenzyme could undergo a single turnover autophosphorylation with adenosine triphosphate and magnesium (MgATP) and trap both products in the crystal lattice, we asked here whether calcium could trap an ATP:RIIβ holoenzyme since the RIIβ holoenzyme is located close to ion channels. The 2.8Å structure of an RIIβp2:C2:(Ca2ADP)2 holoenzyme, supported by biochemical and biophysical data, reveals a trapped single phosphorylation event similar to MgATP. Thus, calcium can mediate a single turnover event with either ATP or adenosine-5'-(β,γ-imido)triphosphate (AMP-PNP), even though it cannot support steady-state catalysis efficiently. The holoenzyme serves as a "product trap" because of the slow off-rate of the pRIIβ subunit, which is controlled by cAMP, not by phosphorylation of the inhibitor site. By quantitatively defining the RIIβ signaling cycle, we show that release of pRIIβ in the presence of cAMP is reduced by calcium, whereas autophosphorylation at the phosphorylation site (P-site) inhibits holoenzyme reassociation with the catalytic subunit. Adding a single phosphoryl group to the preformed RIIβ holoenzyme thus creates a signaling cycle in which phosphatases become an essential partner. This previously unappreciated molecular mechanism is an integral part of PKA signaling for type II holoenzymes. |
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| id | doaj.art-f3af226096054bbfacdf5c8046e4a3ce |
| institution | Directory Open Access Journal |
| issn | 1544-9173 1545-7885 |
| language | English |
| last_indexed | 2024-12-16T06:41:49Z |
| publishDate | 2015-07-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Biology |
| spelling | doaj.art-f3af226096054bbfacdf5c8046e4a3ce2022-12-21T22:40:40ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852015-07-01137e100219210.1371/journal.pbio.1002192Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme.Ping ZhangMatthias J KnapeLalima G AhujaMalik M KeshwaniCharles C KingMira SastriFriedrich W HerbergSusan S TaylorTo provide tight spatiotemporal signaling control, the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) holoenzyme typically nucleates a macromolecular complex or a "PKA signalosome." Using the RIIβ holoenzyme as a prototype, we show how autophosphorylation/dephosphorylation of the RIIβ subunit, as well as cAMP and metal ions, contribute to the dynamics of PKA signaling. While we showed previously that the RIIβ holoenzyme could undergo a single turnover autophosphorylation with adenosine triphosphate and magnesium (MgATP) and trap both products in the crystal lattice, we asked here whether calcium could trap an ATP:RIIβ holoenzyme since the RIIβ holoenzyme is located close to ion channels. The 2.8Å structure of an RIIβp2:C2:(Ca2ADP)2 holoenzyme, supported by biochemical and biophysical data, reveals a trapped single phosphorylation event similar to MgATP. Thus, calcium can mediate a single turnover event with either ATP or adenosine-5'-(β,γ-imido)triphosphate (AMP-PNP), even though it cannot support steady-state catalysis efficiently. The holoenzyme serves as a "product trap" because of the slow off-rate of the pRIIβ subunit, which is controlled by cAMP, not by phosphorylation of the inhibitor site. By quantitatively defining the RIIβ signaling cycle, we show that release of pRIIβ in the presence of cAMP is reduced by calcium, whereas autophosphorylation at the phosphorylation site (P-site) inhibits holoenzyme reassociation with the catalytic subunit. Adding a single phosphoryl group to the preformed RIIβ holoenzyme thus creates a signaling cycle in which phosphatases become an essential partner. This previously unappreciated molecular mechanism is an integral part of PKA signaling for type II holoenzymes.https://doi.org/10.1371/journal.pbio.1002192 |
| spellingShingle | Ping Zhang Matthias J Knape Lalima G Ahuja Malik M Keshwani Charles C King Mira Sastri Friedrich W Herberg Susan S Taylor Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme. PLoS Biology |
| title | Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme. |
| title_full | Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme. |
| title_fullStr | Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme. |
| title_full_unstemmed | Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme. |
| title_short | Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme. |
| title_sort | single turnover autophosphorylation cycle of the pka riiβ holoenzyme |
| url | https://doi.org/10.1371/journal.pbio.1002192 |
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