title: Nuclear actin-related proteins at the core of epigenetic control.
abstract: Nuclear Actin-Related Proteins (ARPs) and actin combine as heterodimers to bind a large helicase subunit and form a core complex essential to the assembly and function of most chromatin remodeling and modifying machines. They are the most common shared subunits of these large and diverse assemblies in eukaryotes. We recently argued that most nuclear ARPs evolved directly from actin prior to the divergence of the eukaryotic kingdoms and did not evolve from pre-existing ARPs.2 Arabidopsis plants defective in nuclear ARP4, ARP5, ARP6, or ARP7 have extreme developmental phenotypes. Our recent publication demonstrates that ARP5-defective plants are not only dwarfed and have aberrant cell sizes, but are also hypersensitive to mutagenic agents that cause double strand DNA breaks.5 In Smith et al.6 we show that ARP6-defective plants, in addition to their extreme developmental phenotypes like small organs and early flowering, present an apparent "Phosphate Starvation Response" with strong morphological and molecular phenotypes. Herein, we interpret our latest data in the light of a hypothesis stating that in addition to their roles in overcoming DNA compaction that affects basal gene expression and silencing, nuclear ARP-containing chromatin complexes exert primary epigenetic control over high-level regulatory factors.
authors.affiliation: Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA USA.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Meagher
authors.affiliation: Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA USA.
authors.forename: Muthugapatti K
authors.initials: MK
authors.lastname: Kandasamy
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA.
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Smith
authors.affiliation: Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, GA USA.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: McKinney
mesh_terms: D000199:Actins / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D044127:Epigenesis, Genetic / Q000187:drug effects; D008840:Microfilament Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D010641:Phenotype; D010710:Phosphates / Q000494:pharmacology; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development
chemical_list: C512743:ATARP5 protein, Arabidopsis; D000199:Actins; D029681:Arabidopsis Proteins; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D010710:Phosphates