Unique features of HIV-1 Rev protein phosphorylation by protein kinase CK2('casein kinase-2')

The HIV-1 Rev transactivator is phosphorylated in vitro by protein kinase C K2 at two residues, Ser-5 and Ser-8; these sites are also phosphorylated in vivo. Here we show that the mechanism by which CK2 phosphorylates Rev is u nique in several respects, notably: (i) it is fully dependent on the regula tory, beta-subunit of CK2; (ii) it relies on the integrity of an acidic str etch of CE2 beta which down-regulates the phosphorylation of other substrat es; (iii) it is inhibited in a dose-dependent manner by polyamines and othe r polycationic effecters that normally stimulate CK2 activity, In contrast, a peptide corresponding to the amino-terminal 26 amino acids of Rev, inclu ding the phosphoacceptor site, is readily phosphorylated by the catalytic s ubunit of CK2 even in the absence of the beta-subunit, These data, in conju nction with the observation that two functionally inactive derivatives of R ev with mutations in its helis-loop-helix motif are refractory to phosphory lation, indicate the phosphorylation of Rev by CK2 relies on conformational features of distinct regions that are also required for the transactivator 's biological activity. (C) 2000 Federation of European Biochemical Societi es, Published by Elsevier Science B.V. All rights reserved.