title: Novel CK2α and CK2β subunits in maize reveal functional diversification in subcellular localization and interaction capacity.
abstract: In plants, CK2α/β subunits are encoded by multigenic families. They assemble as heterotetrameric holoenzymes or remain as individual subunits and are usually located in distinct cell compartments. Here we revise the number of maize CK2α/β genes, bringing them up to a total of eight (four CK2α catalytic and four CK2β regulatory subunits). We characterize CK2β4, which presents nuclear localization and interacts with CK2α1, CK2α3, CK2β1, and CK2β3. We also describe two CK2α isoforms (CK2α2 and CK2α4) containing N-terminal extensions that correspond to putative cTPs (chloroplast transit peptides). These cTPs are functional and responsible for the subcellular localization of CK2α2 and CK2α4 in chloroplasts. Phylogenetic analysis of the CK2α gene family, further supported by the gene structure and architecture of conserved protein domains, reveals the evolutionary expansion and diversification of this family. The subcellular localization of all four CK2α isoforms was found to be altered when were co-expressed with CK2β, thereby pointing to the latter as regulators of CK2α localization.
authors.affiliation: Center for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB Consortium, Campus UAB - Edifici CRAG, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain.
authors.forename: I C
authors.initials: IC
authors.lastname: Vélez-Bermúdez
authors.affiliation: Center for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB Consortium, Campus UAB - Edifici CRAG, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Carretero-Paulet
authors.affiliation: Center for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB Consortium, Campus UAB - Edifici CRAG, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain.
authors.forename: T
authors.initials: T
authors.lastname: Legnaioli
authors.affiliation: Center for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB Consortium, Campus UAB - Edifici CRAG, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Ludevid
authors.affiliation: Center for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB Consortium, Campus UAB - Edifici CRAG, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Pagès
authors.affiliation: Center for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB Consortium, Campus UAB - Edifici CRAG, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain. Electronic address: marta.riera@cragenomica.es.
authors.forename: M
authors.initials: M
authors.lastname: Riera
mesh_terms: D000595:Amino Acid Sequence; D005075:Biological Evolution; D047390:Casein Kinase II / Q000235:genetics* / Q000378:metabolism; D060365:Chloroplast Proteins / Q000378:metabolism; D017343:Genes, Plant; D042541:Intracellular Space; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana; D003313:Zea mays / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
chemical_list: D060365:Chloroplast Proteins; D010940:Plant Proteins; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D021122:Protein Subunits; C078737:chloroplast transit peptides; D047390:Casein Kinase II
keywords: Chloroplast localization; Maize; Protein kinase CK2