Yeast Elf1 factor is phosphorylated and interacts with protein kinase CK2

Abstract

One of the biggest group of proteins influenced by protein kinase CK2 is formed by factors engaged in gene expression. Here we have reported recently identified yeast transcription elongation factor Elf1 as a new substrate for both monomeric and tetrameric forms of CK2. Elf1 serves as a substrate for both the recombinant CK2α′ (Km 0.38 μM) and holoenzyme (Km 0.13 μM). By MALDI-MS we identified the two serine residues at positions 95 and 117 as the most probable in vitro phosphorylation sites. Co-immunoprecypitation experiments show that Elf1 interacts with catalytic (α and α′) as well as regulatory (β and β′) subunits of CK2. These data may help to elucidate the role of protein kinase CK2 and Elf1 in the regulation of transcription elongation.