Swi3p controls SWI/SNF assembly and ATP-dependent H2A-H2B displacement.
Yeast SWI/SNF is a multisubunit, 1.14-MDa ATP-dependent chromatin-remodeling enzyme required for transcription of a subset of inducible genes. Biochemical studies have demonstrated that SWI/SNF uses the energy from ATP hydrolysis to generate superhelical torsion, mobilize mononucleosomes, enhance the accessibility of nucleosomal DNA and remove H2A-H2B dimers from mononucleosomes. Here we describe the ATP-dependent activities of a SWI/SNF sub complex that is composed of only three subunits, Swi2p, Arp7p and Arp9p. Whereas this sub complex is fully functional in most remodeling assays, Swi2p-Arp7p-Arp9p is defective for ATP-dependent removal of H2A-H2B dimers. We identify the acidic N terminus of the Swi3p subunit as a novel H2A-H2B-binding domain required for ATP-dependent dimer loss. Our data indicate that H2A-H2B dimer loss is not an obligatory consequence of ATP-dependent DNA translocation, and furthermore they suggest that SWI/SNF is composed of at least four interdependent modules.
Yang
Xiaofang
X
Interdisciplinary Graduate Program, Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Zaurin
Roser
R
Beato
Miguel
M
Peterson
Craig L
CL
D000255:Adenosine Triphosphate / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly / Q000235:genetics* / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D019281:Dimerization; D006657:Histones / Q000378:metabolism*; D007700:Kinetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
D006657:Histones; D009687:Nuclear Proteins; D009707:Nucleosomes; C072981:SWI3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D000255:Adenosine Triphosphate