title: Arabidopsis kinetochore null2 is an upstream component for centromeric histone H3 variant cenH3 deposition at centromeres.
abstract: The centromeric histone H3 variant cenH3 is an essential centromeric protein required for assembly, maintenance, and proper function of kinetochores during mitosis and meiosis. We identified a kinetochore null2 (KNL2) homolog in Arabidopsis thaliana and uncovered features of its role in cenH3 loading at centromeres. We show that Arabidopsis KNL2 colocalizes with cenH3 and is associated with centromeres during all stages of the mitotic cell cycle, except from metaphase to mid-anaphase. KNL2 is regulated by the proteasome degradation pathway. The KNL2 promoter is mainly active in meristematic tissues, similar to the cenH3 promoter. A knockout mutant for KNL2 shows a reduced level of cenH3 expression and reduced amount of cenH3 protein at chromocenters of meristematic nuclei, anaphase bridges during mitosis, micronuclei in pollen tetrads, and 30% seed abortion. Moreover, knl2 mutant plants display reduced expression of suppressor of variegation 3-9 homologs2, 4, and 9 and reduced DNA methylation, suggesting an impact of KNL2 on the epigenetic environment for centromere maintenance.
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany.
authors.forename: Inna
authors.initials: I
authors.lastname: Lermontova
authors.forename: Markus
authors.initials: M
authors.lastname: Kuhlmann
authors.forename: Swetlana
authors.initials: S
authors.lastname: Friedel
authors.forename: Twan
authors.initials: T
authors.lastname: Rutten
authors.forename: Stefan
authors.initials: S
authors.lastname: Heckmann
authors.forename: Michael
authors.initials: M
authors.lastname: Sandmann
authors.forename: Dmitri
authors.initials: D
authors.lastname: Demidov
authors.forename: Veit
authors.initials: V
authors.lastname: Schubert
authors.forename: Ingo
authors.initials: I
authors.lastname: Schubert
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002503:Centromere / Q000378:metabolism*; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D035264:Flowers / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D017930:Genes, Reporter; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D018386:Kinetochores / Q000378:metabolism*; D008540:Meiosis; D008938:Mitosis; D016254:Mutagenesis, Insertional; D010641:Phenotype; D011401:Promoter Regions, Genetic; D046988:Proteasome Endopeptidase Complex; D036226:Seedlings / Q000166:cytology / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D006657:Histones; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D046988:Proteasome Endopeptidase Complex