PDBsum entry 4wbb

Transferase

PDB id: 4wbb

Contents

Protein chains

269 a.a.

337 a.a.

Ligands

ADP

Metals

_CA ×2

Waters ×42

PDB id:

4wbb

Name:

Transferase

Title:

Single turnover autophosphorylation cycle of the pka riib holoenzyme

Structure:

Camp-dependent protein kinase type ii-beta regulatory subunit. Chain: a. Engineered: yes. Camp-dependent protein kinase catalytic subunit alpha. Chain: b. Synonym: pka c-alpha. Engineered: yes

Source:

Mus musculus. Mouse. Organism_taxid: 10090. Gene: prkar2b. Expressed in: escherichia coli. Expression_system_taxid: 562. Gene: prkaca, pkaca. Expression_system_taxid: 562

Resolution:

2.80Å R-factor: 0.232 R-free: 0.279

Authors:

P.Zhang,M.J.Knape,L.G.Ahuja,M.M.Keshwani,C.C.King,M.Sastri, F.W.Herberg,S.S.Taylor

Key ref:

P.Zhang et al. (2015). Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme. Plos Biol, 13, e1002192. PubMed id: 26158466 DOI: 10.1371/journal.pbio.1002192

Date:

02-Sep-14 Release date: 20-May-15

Protein chain

P31324  (KAP3_MOUSE) -  cAMP-dependent protein kinase type II-beta regulatory subunit from Mus musculus

Seq: 416 a.a.

Struc: 269 a.a.*

Protein chain

P05132  (KAPCA_MOUSE) -  cAMP-dependent protein kinase catalytic subunit alpha from Mus musculus

Seq: 351 a.a.

Struc: 337 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chain B: E.C.2.7.11.11 - cAMP-dependent protein kinase.
• Reaction:
  1. L-seryl-[protein] + ATP = O-phospho-L-seryl-[protein] + ADP + H⁺
  2. L-threonyl-[protein] + ATP = O-phospho-L-threonyl-[protein] + ADP + H⁺

L-seryl-[protein] + ATP = O-phospho-L-seryl-[protein] (Bound ligand (Het Group name = ADP) corresponds exactly) + ADP + H(+)

L-threonyl-[protein] + ATP = O-phospho-L-threonyl-[protein] (Bound ligand (Het Group name = ADP) corresponds exactly) + ADP + H(+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1371/journal.pbio.1002192

Plos Biol 13:e1002192 (2015)

PubMed id: 26158466

Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme.

P.Zhang, M.J.Knape, L.G.Ahuja, M.M.Keshwani, C.C.King, M.Sastri, F.W.Herberg, S.S.Taylor.

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.