ASF1 binds to a heterodimer of histones H3 and H4: a two-step mechanism for the assembly of the H3-H4 heterotetramer on DNA.
The first step in the formation of the nucleosome is commonly assumed to be the deposition of a histone H3-H4 heterotetramer onto DNA. Antisilencing function 1 (ASF1) is a major histone H3-H4 chaperone that deposits histones H3 and H4 onto DNA. With a goal of understanding the mechanism of deposition of histones H3 and H4 onto DNA, we have determined the stoichiometry of the Asf1-H3-H4 complex. We have established that a single molecule of Asf1 binds to an H3-H4 heterodimer using gel filtration, amino acid, reversed-phase chromatography, and analytical ultracentrifugation analyses. We demonstrate that Asf1 blocks formation of the H3-H4 heterotetramer by a mechanism that likely involves occlusion of the H3-H3 dimerization interface.
English
Christine M
CM
Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center at Fitzsimons, Aurora, Colorado 80045, USA.
Maluf
Nasib K
NK
Tripet
Brian
B
Churchill
Mair E A
ME
Tyler
Jessica K
JK
D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000378:metabolism*; D019281:Dimerization; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D018832:Molecular Chaperones; D008970:Molecular Weight; D009707:Nucleosomes / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D014461:Ultracentrifugation
C109731:ASF1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D006657:Histones; D018832:Molecular Chaperones; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA