Network of dynamic interactions between histone H1 and high-mobility-group proteins in chromatin.
Histone H1 and the high-mobility group (HMG) proteins are chromatin binding proteins that regulate gene expression by modulating the compactness of the chromatin fiber and affecting the ability of regulatory factors to access their nucleosomal targets. Histone H1 stabilizes the higher-order chromatin structure and decreases nucleosomal access, while the HMG proteins decrease the compactness of the chromatin fiber and enhance the accessibility of chromatin targets to regulatory factors. Here we show that in living cells, each of the three families of HMG proteins weakens the binding of H1 to nucleosomes by dynamically competing for chromatin binding sites. The HMG families weaken H1 binding synergistically and do not compete among each other, suggesting that they affect distinct H1 binding sites. We suggest that a network of dynamic and competitive interactions involving HMG proteins and H1, and perhaps other structural proteins, constantly modulates nucleosome accessibility and the local structure of the chromatin fiber.
Catez
Frédéric
F
National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Yang
Huan
H
Tracey
Kevin J
KJ
Reeves
Raymond
R
Misteli
Tom
T
Bustin
Michael
M
D000818:Animals; D041702:BALB 3T3 Cells; D001665:Binding Sites; D001667:Binding, Competitive; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins; D006609:High Mobility Group Proteins / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D002843:Chromatin; D006609:High Mobility Group Proteins; D006657:Histones; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins