title: Different domains control the localization and mobility of LIKE HETEROCHROMATIN PROTEIN1 in Arabidopsis nuclei.
abstract: Plants possess a single gene for the structurally related HETEROCHROMATIN PROTEIN1 (HP1), termed LIKE-HP1 (LHP1). We investigated the subnuclear localization, binding properties, and dynamics of LHP1 proteins in Arabidopsis thaliana cells. Transient expression assays showed that tomato (Solanum lycopersicum) LHP1 fused to green fluorescent protein (GFP; Sl LHP1-GFP) and Arabidopsis LHP1 (At LHP1-GFP) localized to heterochromatic chromocenters and showed punctuated distribution within the nucleus; tomato but not Arabidopsis LHP1 was also localized within the nucleolus. Mutations of aromatic cage residues that recognize methyl K9 of histone H3 abolished their punctuated distribution and localization to chromocenters. Sl LHP1-GFP plants displayed cell type-dependent subnuclear localization. The diverse localization pattern of tomato LHP1 did not require the chromo shadow domain (CSD), whereas the chromodomain alone was insufficient for localization to chromocenters; a nucleolar localization signal was identified within the hinge region. Fluorescence recovery after photobleaching showed that Sl LHP1 is a highly mobile protein whose localization and retention are controlled by distinct domains; retention at the nucleolus and chromocenters is conferred by the CSD. Our results imply that LHP1 recruitment to chromatin is mediated, at least in part, through interaction with methyl K9 and that LHP1 controls different nuclear processes via transient binding to its nuclear sites.
authors.affiliation: Department of Plant Sciences, Weizman Institute of Science, Rehovot, Israel.
authors.forename: Assaf
authors.initials: A
authors.lastname: Zemach
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Hagit
authors.initials: H
authors.lastname: Ben-Meir
authors.forename: Moran
authors.initials: M
authors.lastname: Oliva
authors.forename: Assaf
authors.initials: A
authors.lastname: Mosquna
authors.forename: Vladimir
authors.initials: V
authors.lastname: Kiss
authors.forename: Yigal
authors.initials: Y
authors.lastname: Avivi
authors.forename: Nir
authors.initials: N
authors.lastname: Ohad
authors.forename: Gideon
authors.initials: G
authors.lastname: Grafi
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002503:Centromere / Q000235:genetics / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D006657:Histones / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C443901:like heterochromatin protein 1