title: Phosphorylation of maize eukaryotic translation initiation factor on Ser2 by catalytic subunit CK2.
abstract: 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. Wild-type ZmeIF5A was distributed evenly between nucleus and cytoplasm, but the replacement of Ser2 by aspartic acid, which mimics the phosphorylated serine, influences its intracellular localization. We postulate that phosphorylation of Ser2 in maize eIF5A, and most probably in other plant cells, plays a role in specific regulation of nuclear export of eIF5A-bound mRNAs.
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warszawa, Poland.
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Lewandowska-Gnatowska
authors.forename: Lidia
authors.initials: L
authors.lastname: Szymona
authors.forename: Maja
authors.initials: M
authors.lastname: Łebska
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Szczegielniak
authors.forename: Grażyna
authors.initials: G
authors.lastname: Muszyńska
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D003313:Zea mays / Q000201:enzymology*; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D050505:Mutant Proteins; D010448:Peptide Initiation Factors; D010768:Phosphoserine; D010940:Plant Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A