4WBB

Single Turnover Autophosphorylation Cycle of the PKA RIIb Holoenzyme

Summary for 4WBB

• Entry DOI: 10.2210/pdb4wbb/pdb
• Descriptor: cAMP-dependent protein kinase type II-beta regulatory subunit, cAMP-dependent protein kinase catalytic subunit alpha, CALCIUM ION, ... (5 entities in total)
• Functional Keywords: pka, complex, single turnover, oscillations, transferase
• Biological source: Mus musculus (Mouse); More
• Total number of polymer chains: 2
• Total formula weight: 87518.60

Authors

Zhang, P.,Knape, M.J.,Ahuja, L.G.,Keshwani, M.M.,King, C.C.,Sastri, M.,Herberg, F.W.,Taylor, S.S. (deposition date: 2014-09-02, release date: 2015-05-20, Last modification date: 2024-10-30)

Primary citation

Zhang, P.,Knape, M.J.,Ahuja, L.G.,Keshwani, M.M.,King, C.C.,Sastri, M.,Herberg, F.W.,Taylor, S.S.
Single Turnover Autophosphorylation Cycle of the PKA RII beta Holoenzyme.
Plos Biol., 13:e1002192-e1002192, 2015

PubMed Abstract: 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.

PubMed: 26158466
DOI: 10.1371/journal.pbio.1002192

Experimental method

X-RAY DIFFRACTION (2.8 Å)