Highly preferential nucleation of histone H1 assembly on scaffold-associated regions.
Scaffold-associated regions (SARs) are A + T-rich DNA regions of several hundred base-pairs that are known to bind specifically to nuclear or metaphase scaffolds. Surprisingly, histone H1 specifically associates with SARs. Under conditions of high co-operativity, at input ratios of H1 to DNA up to 15% (w/w), histone H1 binds preferentially to those DNA molecules harboring a SAR, leaving the non-SAR fragments free. Our experiments identify SARs as cis-acting sequences that nucleate co-operative H1 assembly along the SAR into the flanking non-SAR DNA. Experiments with simple DNA polymers implicate homopolymeric oligo(dA).oligo(dT) tracts in preferential histone H1 assembly. The homopolymer oligo(dA).oligo(dT) is, above a critical length of 130 base-pairs, a highly specific nucleator of H1 assembly. SARs may control the conformation of chromatin domains via a regulated H1 assembly and set up the potential transcriptional repertoire of the cell.
Izaurralde
E
E
Department of Molecular Biology, University of Geneva, Switzerland.
Käs
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E
Laemmli
U K
UK
D000818:Animals; D001483:Base Sequence; D002843:Chromatin / Q000648:ultrastructure*; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism*; D003852:Deoxyribonucleoproteins / Q000648:ultrastructure; D006657:Histones / Q000378:metabolism*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009687:Nuclear Proteins / Q000378:metabolism*; D010957:Plasmids; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid
D002843:Chromatin; D003852:Deoxyribonucleoproteins; D006657:Histones; D009687:Nuclear Proteins; D004247:DNA