The SIN domain of the histone octamer is essential for intramolecular folding of nucleosomal arrays.
The SIN domain within histones H3 and H4 is defined by a set of single amino acid substitutions that were initially identified as mutations that alleviate the transcriptional defects associated with inactivation of the SWI/SNF chromatin remodeling complex. Here we use recombinant histones to investigate how Sin- versions of H4 alter the structure of nucleosomal arrays. We find that an R45C substitution within the SIN domain of H4 does not disrupt nucleosome positioning nor does this Sin- version alter the accessibility of nucleosomal DNA. In contrast, we find that the R45C substitution eliminates Mg2+-dependent, intramolecular folding of the nucleosomal arrays. Our results suggest that Sin- versions of histones may alleviate the need for SWI/SNF in vivo by disrupting higher-order chromatin folding.
Horn
Peter J
PJ
Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Crowley
Kimberly A
KA
Carruthers
Lenny M
LM
Hansen
Jeffrey C
JC
Peterson
Craig L
CL
D000255:Adenosine Triphosphate / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D002645:Chickens; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006657:Histones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D009687:Nuclear Proteins; D009690:Nucleic Acid Conformation / Q000187:drug effects; D009707:Nucleosomes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000187:drug effects; D012341:RNA, Ribosomal, 5S / Q000235:genetics; D012492:Salts / Q000494:pharmacology; D012617:Sea Urchins / Q000235:genetics; D013698:Templates, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; D009707:Nucleosomes; D012341:RNA, Ribosomal, 5S; D012492:Salts; D014157:Transcription Factors; D029867:Xenopus Proteins; D000255:Adenosine Triphosphate; D008274:Magnesium