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Proteomes 2015, 3(2), 89-116; doi:10.3390/proteomes3020089

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

1
Department of Biochemistry, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
2
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)
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Abstract

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
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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.

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