title: Evidence for monomeric actin function in INO80 chromatin remodeling.
abstract: Actin has well-established functions in the cytoplasm, but its roles in the nucleus remain poorly defined. Here, by studying the nuclear actin-containing yeast INO80 chromatin remodeling complex, we provide genetic and biochemical evidence for a role of monomeric actin in INO80 chromatin remodeling. We demonstrate that, in contrast to cytoplasmic actin, nuclear actin is present as a monomer in the INO80 complex, and its barbed end is not accessible for polymerization. We identify an actin mutation in subdomain 2 affecting in vivo nuclear functions and reducing the chromatin remodeling activity of the INO80 complex in vitro. Notably, the highly conserved subdomain 2 at the pointed end of actin contributes to the interaction of INO80 with chromatin. Our results establish an evolutionarily conserved function of nuclear actin in its monomeric form and suggest that nuclear actin can utilize a fundamentally distinct mechanism from that of cytoplasmic actin.
authors.affiliation: Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, USA.
authors.forename: Prabodh
authors.initials: P
authors.lastname: Kapoor
authors.forename: Mingming
authors.initials: M
authors.lastname: Chen
authors.forename: Duane David
authors.initials: DD
authors.lastname: Winkler
authors.forename: Karolin
authors.initials: K
authors.lastname: Luger
authors.forename: Xuetong
authors.initials: X
authors.lastname: Shen
mesh_terms: D000199:Actins / Q000737:chemistry / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D042002:Chromatin Assembly and Disassembly; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
chemical_list: D000199:Actins; C483404:INO80 complex, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins