Marin O, Sarno S, Boschetti M, Pagano M A, Meggio F, Ciminale V, D'Agostino D M, Pinna L A
Dipartmento di Chimica Biologica and Centro del CNR per lo Studio delle Biomembrane, Università delgi Studi di Padova, Padua, Italy.
FEBS Lett. 2000 Sep 8;481(1):63-7. doi: 10.1016/s0014-5793(00)01971-2.
The HIV-1 Rev transactivator is phosphorylated in vitro by protein kinase CK2 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 unique in several respects, notably: (i) it is fully dependent on the regulatory, beta-subunit of CK2; (ii) it relies on the integrity of an acidic stretch of CK2 beta which down-regulates the phosphorylation of other substrates; (iii) it is inhibited in a dose-dependent manner by polyamines and other polycationic effectors that normally stimulate CK2 activity. In contrast, a peptide corresponding to the amino-terminal 26 amino acids of Rev, including the phosphoacceptor site, is readily phosphorylated by the catalytic subunit of CK2 even in the absence of the beta-subunit. These data, in conjunction with the observation that two functionally inactive derivatives of Rev with mutations in its helix-loop-helix motif are refractory to phosphorylation, indicate the phosphorylation of Rev by CK2 relies on conformational features of distinct regions that are also required for the transactivator's biological activity.
HIV-1 Rev反式激活因子在体外可被蛋白激酶CK2在两个位点（Ser-5和Ser-8）磷酸化；这些位点在体内也会发生磷酸化。在此我们表明，CK2使Rev磷酸化的机制在几个方面具有独特性，尤其是：（i）它完全依赖于CK2的调节性β亚基；（ii）它依赖于CK2β一段酸性序列的完整性，该序列会下调其他底物的磷酸化；（iii）它会被通常刺激CK2活性的多胺和其他聚阳离子效应物以剂量依赖的方式抑制。相反，与Rev氨基末端26个氨基酸对应的肽，包括磷酸化位点，即使在没有β亚基的情况下也能被CK2催化亚基轻易磷酸化。这些数据，结合Rev的螺旋-环-螺旋基序中有两个功能失活衍生物对磷酸化具有抗性这一观察结果，表明CK2对Rev的磷酸化依赖于不同区域的构象特征，而这些特征也是反式激活因子生物活性所必需的。
