H2A.Z and H3.3 histone variants affect nucleosome structure: biochemical and biophysical studies.
Histone variants play important roles in regulation of chromatin structure and function. To understand the structural role played by histone variants H2A.Z and H3.3, both of which are implicated in transcription regulation, we conducted extensive biochemical and biophysical analysis on mononucleosomes reconstituted from either random-sequence DNA derived from native nucleosomes or a defined DNA nucleosome positioning sequence and recombinant human histones. Using established electrophoretic and sedimentation analysis methods, we compared the properties of nucleosomes containing canonical histones and histone variants H2A.Z and H3.3 (in isolation or in combination). We find only subtle differences in the compaction and stability of the particles. Interestingly, both H2A.Z and H3.3 affect nucleosome positioning, either creating new positions or altering the relative occupancy of the existing nucleosome position space. On the other hand, only H2A.Z-containing nucleosomes exhibit altered linker histone binding. These properties could be physiologically significant as nucleosome positions and linker histone binding partly determine factor binding accessibility.
Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071, USA.
Amit
A
Thakar
Pooja
P
Gupta
Toyotaka
T
Ishibashi
Ron
R
Finn
Begonia
B
Silva-Moreno
Susumu
S
Uchiyama
Kiichi
K
Fukui
Miroslav
M
Tomschik
Juan
J
Ausio
Jordanka
J
Zlatanova
D000818:Animals; D001669:Biochemical Phenomena; D055592:Biophysical Phenomena; D002645:Chickens; D042002:Chromatin Assembly and Disassembly; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009707:Nucleosomes / Q000737:chemistry* / Q000378:metabolism*; D009994:Osmolar Concentration; D011485:Protein Binding / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012617:Sea Urchins; D014461:Ultracentrifugation
D006657:Histones; D009707:Nucleosomes; D011994:Recombinant Proteins; C077020:histone H2A.F-Z; D004247:DNA