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

Proteomes

William K. Ray²  Mark B. Potters²  January D. Haile¹  Peter J. Kennelly² 

[1]Department of Chemistry, Centre College, Danville, KY 40422, USA

[2] E-Mail:

[3]Department of Biochemistry, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA

[4] E-Mails:

关键词: protein phosphorylation;    stress signaling;    crenarchaea;   

DOI  :  10.3390/proteomes3020089

来源: mdpi

【 摘 要 】

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 (K_i 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, K_m, but had little effect on V_max. Autophosphorylation activated SsoPK4 and rendered it insensitive to oxidized Coenzyme A.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.