Next Article in Journal
Partial-Body Irradiation in Patients with Prostate Cancer Treated with IMRT Has Little Effect on the Composition of Serum Proteome
Next Article in Special Issue
Fluorescent Reporters and Biosensors for Probing the Dynamic Behavior of Protein Kinases
Previous Article in Journal
Regional Specializations of the PAZ Proteomes Derived from Mouse Hippocampus, Olfactory Bulb and Cerebellum
Article Menu

Export Article

Open AccessArticle
Proteomes 2015, 3(2), 89-116;

Activation of SsoPK4, an Archaeal eIF2α Kinase Homolog, by Oxidized CoA

Department of Biochemistry, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
Department of Chemistry, Centre College, Danville, KY 40422, USA
Author to whom correspondence should be addressed.
Academic Editor: Lee M. Graves
Received: 11 February 2015 / Revised: 30 April 2015 / Accepted: 5 May 2015 / Published: 15 May 2015
(This article belongs to the Special Issue Probing the Dynamic Properties of the Kinome)
Full-Text   |   PDF [2169 KB, uploaded 15 May 2015]   |  


The eukaryotic protein kinase (ePK) paradigm provides integral components for signal transduction cascades throughout nature. However, while so-called typical ePKs permeate the Eucarya and Bacteria, atypical ePKs dominate the kinomes of the Archaea. Intriguingly, the catalytic domains of the handful of deduced typical ePKs from the archaeon Sulfolobus solfataricus P2 exhibit significant resemblance to the protein kinases that phosphorylate translation initiation factor 2α (eIF2α) in response to cellular stresses. We cloned and expressed one of these archaeal eIF2α protein kinases, SsoPK4. SsoPK4 exhibited protein-serine/threonine kinase activity toward several proteins, including the S. solfataricus homolog of eIF2α, aIF2α. The activity of SsoPK4 was inhibited in vitro by 3ʹ,5ʹ-cyclic AMP (Ki of ~23 µM) and was activated by oxidized Coenzyme A, an indicator of oxidative stress in the Archaea. Activation enhanced the apparent affinity for protein substrates, Km, but had little effect on Vmax. Autophosphorylation activated SsoPK4 and rendered it insensitive to oxidized Coenzyme A. View Full-Text
Keywords: protein phosphorylation; stress signaling; crenarchaea protein phosphorylation; stress signaling; crenarchaea

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Ray, W.K.; Potters, M.B.; Haile, J.D.; Kennelly, P.J. Activation of SsoPK4, an Archaeal eIF2α Kinase Homolog, by Oxidized CoA. Proteomes 2015, 3, 89-116.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Proteomes EISSN 2227-7382 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top