title: Identification and characterization of plant Haspin kinase as a histone H3 threonine kinase.
abstract: BACKGROUND
  Haspin kinases are mitotic kinases that are well-conserved from yeast to human. Human Haspin is a histone H3 Thr3 kinase that has important roles in chromosome cohesion during mitosis. Moreover, phosphorylation of histone H3 at Thr3 by Haspin in fission yeast, Xenopus, and human is required for accumulation of Aurora B on the centromere, and the subsequent activation of Aurora B kinase activity for accurate chromosome alignment and segregation. Although extensive analyses of Haspin have been carried out in yeast and animals, the function of Haspin in organogenesis remains unclear.
  
  
  RESULTS
  Here, we identified a Haspin kinase, designated AtHaspin, in Arabidopsis thaliana. The purified AtHaspin phosphorylated histone H3 at both Thr3 and Thr11 in vitro. Live imaging of AtHaspin-tdTomato and GFP-α-tubulin in BY-2 cells showed that AtHaspin-tdTomato localized on chromosomes during prometaphase and metaphase, and around the cell plate during cytokinesis. This localization of AtHaspin overlapped with that of phosphorylated Thr3 and Thr11 of histone H3 in BY-2 cells. AtHaspin-GFP driven by the native promoter was expressed in root meristems, shoot meristems, floral meristems, and throughout the whole embryo at stages of high cell division. Overexpression of a kinase domain mutant of AtHaspin decreased the size of the root meristem, which delayed root growth.
  
  
  CONCLUSIONS
  Our results indicated that the Haspin kinase is a histone H3 threonine kinase in A. thaliana. AtHaspin phosphorylated histone H3 at both Thr3 and Thr11 in vitro. The expression and dominant-negative analysis showed that AtHaspin may have a role in mitotic cell division during plant growth. Further analysis of coordinated mechanisms involving Haspin and Aurora kinases will shed new light on the regulation of chromosome segregation in cell division during plant growth and development.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kurihara
authors.forename: Sachihiro
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Omura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Higashiyama
authors.forename: Kiichi
authors.initials: K
authors.lastname: Fukui
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D002478:Cells, Cultured; D032461:Chromosomes, Plant / Q000378:metabolism; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D049452:Green Fluorescent Proteins; D006657:Histones / Q000378:metabolism; D007399:Interphase; D018519:Meristem / Q000166:cytology; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013912:Threonine / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D006657:Histones; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D013912:Threonine; D017346:Protein Serine-Threonine Kinases