title: Interactions between the nucleosome histone core and Arp8 in the INO80 chromatin remodeling complex.
abstract: Actin-related protein Arp8 is a component of the INO80 chromatin remodeling complex. Yeast Arp8 (yArp8) comprises two domains: a 25-KDa N-terminal domain, found only in yeast, and a 75-KDa C-terminal domain (yArp8CTD) that contains the actin fold and is conserved across other species. The crystal structure shows that yArp8CTD contains three insertions within the actin core. Using a combination of biochemistry and EM, we show that Arp8 forms a complex with nucleosomes, and that the principal interactions are via the H3 and H4 histones, mediated through one of the yArp8 insertions. We show that recombinant yArp8 exists in monomeric and dimeric states, but the dimer is the biologically relevant form required for stable interactions with histones that exploits the twofold symmetry of the nucleosome core. Taken together, these data provide unique insight into the stoichiometry, architecture, and molecular interactions between components of the INO80 remodeling complex and nucleosomes, providing a first step toward building up the structure of the complex.
authors.affiliation: Chester Beatty Laboratories,  Institute of Cancer Research, London SW3 6JB,  United Kingdom.
authors.forename: Matheshwaran
authors.initials: M
authors.lastname: Saravanan
authors.forename: Jochen
authors.initials: J
authors.lastname: Wuerges
authors.forename: Daniel
authors.initials: D
authors.lastname: Bose
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: McCormack
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Cook
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhang
authors.forename: Dale B
authors.initials: DB
authors.lastname: Wigley
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D001665:Binding Sites; D042002:Chromatin Assembly and Disassembly; D018360:Crystallography, X-Ray / Q000379:methods; D019281:Dimerization; D006657:Histones / Q000737:chemistry*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008840:Microfilament Proteins / Q000737:chemistry*; D008958:Models, Molecular; D009707:Nucleosomes / Q000737:chemistry / Q000378:metabolism*; D009711:Nucleotides / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*
chemical_list: C521742:ARP8 protein, S cerevisiae; D006657:Histones; C483404:INO80 complex, S cerevisiae; D008840:Microfilament Proteins; D009707:Nucleosomes; D009711:Nucleotides; D029701:Saccharomyces cerevisiae Proteins; D000244:Adenosine Diphosphate