Phosphorylation of maize eukaryotic translation initiation factor on Ser2 by catalytic subunit CK2.

Alignment of eukaryotic translation initiation factor 5A (eIF5A) sequences has shown, for plants, in contrast to most other eukaryotes, the presence of N-terminal serine residue (Ser2) which could be phosphorylated by CK2. Using point directed mutagenesis, we demonstrate here that in recombinant maize ZmeIF5Awt Ser2 is exclusively phosphorylated by catalytic subunit of CK2 (CK2α), whereas its mutated variant Ser2Ala is not phosphorylated. To shed light on the physiological significance of this Ser2 phosphorylation, transient expression of fluorescence-labeled proteins was performed in maize protoplast.

Relative role of halogen bonds and hydrophobic interactions in inhibition of human protein kinase CK2α by tetrabromobenzotriazole and some C5-substituted analogues.

To examine the relative role of halogen bonding and hydrophobic interactions in the inhibition of human CK2alpha by 4,5,6,7-tetrabromobenzotriazole (TBBt), we have synthesized a series of 5-substituted benzotriazoles (Bt) and the corresponding 5-substituted 4,6,7-tribromobenzotriazoles (Br3Bt) and examined their inhibition of human CK2alpha relative to that of TBBt. The various C(5) substituents differ in size (H and CH3), electronegativity (NH2 and NO2), and hydrophobicity (COOH and Cl). Some substituents were halogen bond donors (Cl, Br), while others were fluorine bond donors (F and CF3).

Phosphorylation of maize eukaryotic translation initiation factor 5A (eIF5A) by casein kinase 2: identification of phosphorylated residue and influence on intracellular localization of eIF5A.

Maize eukaryotic translation initiation factor 5A (ZmeIF5A) co-purifies with the catalytic alpha subunit of protein kinase CK2 and is phosphorylated by this enzyme. Phosphorylated ZmeIF5A was also identified after separation of maize leaf proteins by two-dimensional electrophoresis. Multiple sequence alignment of eIF5A proteins showed that in monocots, in contrast to other eukaryotes, there are two serine/threonine residues that could potentially be phosphorylated by CK2.

A novel splicing variant encoding putative catalytic alpha subunit of maize protein kinase CK2.

A cDNA highly homologous to the known catalytic alpha subunit of protein kinase CK2 was cloned from maize (Zea mays). It was designated ZmCK2alpha-4 (accession no. AAF76187).

Synthesis of new analogs of benzotriazole, benzimidazole and phthalimide--potential inhibitors of human protein kinase CK2.

New derivatives of 4,5,6,7-tetrabromo-1H-1,2,3-benzotriazole (TBBt), 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi), and N-substituted tetrabromophthalimides were synthesized and their effect on the activity of human protein kinase CK2 was examined. The most active were derivatives with N-hydroxypropyl substituents (IC(50) in 0.32-0.

New inhibitors of protein kinase CK2, analogues of benzimidazole and benzotriazole.

Derivatives of 4,5,6,7-tetrabromobenzotriazole (TBBt) and 4,5,6,7-tetrabromobenzimidazole (TBBi) with IC50 in the low micromolar range and with high selectivity belong to the most promising inhibitors of protein kinase CK2 (casein kinase 2). Treatment of various cell lines with TBBt, TBBi or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT) affected cell viability with simultaneous induction of apoptosis. The inhibitory activity of newly synthesized hydroxyalkyl derivatives of TBBi and TBBt depends on the length of the alkyl chain.