title: Functional characterization of the diatom cyclin-dependent kinase A2 as a mitotic regulator reveals plant-like properties in a non-green lineage.
abstract: BACKGROUND
  Cyclin-dependent kinases (CDKs) are crucial regulators of cell cycle progression in eukaryotes. The diatom CDKA2 was originally assigned to the classical A-type CDKs, but its cell cycle phase-specific transcription at the G2-to-M phase transition is typical for plant-specific B-type CDKs.
  
  
  RESULTS
  Here, we report the functional characterization of CDKA2 from the diatom Phaeodactylum tricornutum. Through a yeast two-hybrid library screen, CDKA2 was found to interact with the G2/M-specific CDK scaffolding factor CKS1. Localization of CDKA2 was found to be nuclear in interphase cells, while in cells undergoing cytokinesis, the signal extended to the cell division plane. In addition, overexpression of CDKA2 induced an overall reduction in the cell growth rate. Expression analysis of cell cycle marker genes in the overexpression lines indicates that this growth reduction is primarily due to a prolongation of the mitotic phase.
  
  
  CONCLUSIONS
  Our study indicates a role for CDKA2 during cell division in diatoms. The functional characterization of a CDK with clear CDKB properties in a non-green organism questions whether the current definition of B-type CDKs being plant-specific might need revision.
authors.affiliation: Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. marie.huysman@psb.vib-ugent.be.|Department of Plant Systems Biology, VIB, and Bioinformatics, Ghent University, 9052, Ghent, Belgium. marie.huysman@psb.vib-ugent.be.|Protistology and Aquatic Ecology, Department of Biology, Ghent University, 9000, Ghent, Belgium. marie.huysman@psb.vib-ugent.be.|Environmental and Evolutionary Genomics Section, Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8186, Institut National de la Santé et de la Recherche Médicale U1024, Ecole Normale Supérieure, 75230, Paris, Cedex 05, France. marie.huysman@psb.vib-ugent.be.
authors.forename: Marie J J
authors.initials: MJ
authors.lastname: Huysman
authors.affiliation: Environmental and Evolutionary Genomics Section, Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8186, Institut National de la Santé et de la Recherche Médicale U1024, Ecole Normale Supérieure, 75230, Paris, Cedex 05, France. tanaka@fsc.hokudai.ac.jp.|Current address: Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, Hokkaido, 051-0013, Japan. tanaka@fsc.hokudai.ac.jp.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Environmental and Evolutionary Genomics Section, Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8186, Institut National de la Santé et de la Recherche Médicale U1024, Ecole Normale Supérieure, 75230, Paris, Cedex 05, France. cbowler@biologie.ens.fr.
authors.forename: Chris
authors.initials: C
authors.lastname: Bowler
authors.affiliation: Protistology and Aquatic Ecology, Department of Biology, Ghent University, 9000, Ghent, Belgium. Wim.Vyverman@UGent.be.
authors.forename: Wim
authors.initials: W
authors.lastname: Vyverman
authors.affiliation: Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. lieven.deveylder@psb.vib-ugent.be.|Department of Plant Systems Biology, VIB, and Bioinformatics, Ghent University, 9052, Ghent, Belgium. lieven.deveylder@psb.vib-ugent.be.
authors.forename: Lieven
authors.initials: L
authors.lastname: De Veylder
mesh_terms: D020418:Algal Proteins / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000502:physiology*; D017377:Diatoms / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D008938:Mitosis; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D020418:Algal Proteins; D018844:Cyclin-Dependent Kinases