PDBsum entry 3qal

Transferase/transferase inhibitor

PDB id: 3qal

Contents

Protein chains

341 a.a.

18 a.a.

Ligands

ATP

Metals

_MG ×2

Waters ×373

PDB id:

3qal

Name:

Transferase/transferase inhibitor

Title:

Crystal structure of arg280ala mutant of catalytic subunit of camp- dependent protein kinase

Structure:

Camp-dependent protein kinase catalytic subunit alpha. Chain: e. Synonym: pka c-alpha. Engineered: yes. Mutation: yes. Protein kinase inhibitor. Chain: i. Fragment: unp residues 6-23. Engineered: yes

Source:

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

Resolution:

1.70Å R-factor: 0.176 R-free: 0.194

Authors:

J.Yang,J.Wu,J.Steichen,S.S.Taylor

Key ref:

J.Yang et al. (2012). A conserved Glu-Arg salt bridge connects coevolved motifs that define the eukaryotic protein kinase fold. J Mol Biol, 415, 666-679. PubMed id: 22138346

Date:

11-Jan-11 Release date: 07-Dec-11

Protein chain

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

Seq: 351 a.a.

Struc: 341 a.a.*

Protein chain

P63248  (IPKA_MOUSE) -  cAMP-dependent protein kinase inhibitor alpha from Mus musculus

Seq: 76 a.a.

Struc: 18 a.a.

* PDB and UniProt seqs differ at 6 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chain E: 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] (Bound ligand (Het Group name = ATP) corresponds exactly) + ATP = O-phospho-L-seryl-[protein] + ADP + H(+)

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

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

reference

J Mol Biol 415:666-679 (2012)

PubMed id: 22138346

A conserved Glu-Arg salt bridge connects coevolved motifs that define the eukaryotic protein kinase fold.

J.Yang, J.Wu, J.M.Steichen, A.P.Kornev, M.S.Deal, S.Li, B.Sankaran, V.L.Woods, S.S.Taylor.

ABSTRACT

Eukaryotic protein kinases (EPKs) feature two coevolved structural segments, the Activation segment, which starts with the Asp-Phe-Gly (DFG) and ends with the Ala-Pro-Glu (APE) motifs, and the helical GHI subdomain that comprises αG-αH-αI helices. Eukaryotic-like kinases have a much shorter Activation segment and lack the GHI subdomain. They thus lack the conserved salt bridge interaction between the APE Glu and an Arg from the GHI subdomain, a hallmark signature of EPKs. Although the conservation of this salt bridge in EPKs is well known and its implication in diseases has been illustrated by polymorphism analysis, its function has not been carefully studied. In this work, we use murine cAMP-dependent protein kinase (protein kinase A) as the model enzyme (Glu208 and Arg280) to examine the role of these two residues. We showed that Ala replacement of either residue caused a 40- to 120-fold decrease in catalytic efficiency of the enzyme due to an increase in K(m)(ATP) and a decrease in k(cat). Crystal structures, as well as solution studies, also demonstrate that this ion pair contributes to the hydrophobic network and stability of the enzyme. We show that mutation of either Glu or Arg to Ala renders both mutant proteins less effective substrates for upstream kinase phosphoinositide-dependent kinase 1. We propose that the Glu208-Arg280 pair serves as a center hub of connectivity between these two structurally conserved elements in EPKs. Mutations of either residue disrupt communication not only between the two segments but also within the rest of the molecule, leading to altered catalytic activity and enzyme regulation.