Carboxyl-terminal peptides from histone H1 variants: DNA binding characteristics and solution conformation

Abstract

The carboxyl‐terminal domains of the histone H1 proteins bind to DNA and are important in condensation of DNA. Little is known about the details of the interactions between H1 histones and DNA, and in particular, there is little known about differences among variant H1 histones in their interactions with DNA. Questions concerning H1 histone‐DNA affinity and H1 conformation were investigated using peptide fragments from the carboxyl terminal domains of four nonallelic histone H1 variant proteins (mouse H1‐1, H1‐4 and H1°, and rat H1T). Three of the four peptides showed a slight preference for binding to a GC‐rich region of a 214‐base‐pair DNA fragment, rather than to an AT‐rich region. The fourth peptide, H1t, appeared to bind preferentially to the AT‐rich region of the 214‐base‐pair fragment. The results show that these small peptides bind preferentially to a subset of DNA sequences; such sequence preference might be exhibited by the intact H1 histones themselves. CD spectra of the peptides, which are from regions of the proteins that are not compactly folded, showed that the α‐helical content of the peptides was minimal if the peptides were in 10 mM phosphate buffer, but increased if the peptides were in 1 M NaClO4 and 50% trifluoroethanol, conditions that are postulated to approximate certain aspects of binding to DNA. H1‐4 peptide, which was predicted to be 70% α‐helix, but was not α‐helical in 10 mM phosphate buffer, appeared from difference CD spectra to be more α‐helical when it was bound to DNA. The regions of the proteins from which these peptides are derived, which are extended in solution, may fold, forming α‐helices, upon binding to DNA. © 1996 John Wiley & Sons, Inc.

The Requirement of H1 Histones for a Heterodimeric Nuclear Import Receptor

“…This implies that the tendency for aggregation is caused by the nature of the entire C-terminal domain. It has been shown that the C-terminal domain of H1 histone is involved in the formation of higher order chromatin structures (36) by binding to DNA and by interaction with other H1 molecules (37,38). Therefore, it may be that intermolecular interactions of the C-terminal domain or binding to nucleic acids may cause the observed aggregation.…”

Xbp1, a Stress-Induced Transcriptional Repressor of the Saccharomyces cerevisiae Swi4/Mbp1 Family

“…This region may contribute to the DNA-binding activity of Xbp1 and could possibly compensate for the missing HTH motif found in the other family members, since this carboxy-terminal domain of the histone H1 variants is sufficient to bind DNA and efficiently condense chromatin (21,58). This latter property may also provide a clue to the mechanism by which Xbp1 represses transcription.…”

Histone H1 and chromatin interactions in human fibroblast nuclei after H1 depletion and reconstitution with H1 subfractions

“…Recent results have indicated that the C-terminal domains of H1 proteins are primarily responsible for their DNA-binding properties (74), and it has been shown that synthetic peptides from the C-terminal domain of different H1 isoforms, including H1°, do not differ in their affinity for DNA (75). Recent experiments using H1-green fluorescent protein fusion proteins and photobleaching techniques have indicated a continuous and rapid exchange of H1 molecules in living cells (76,77).…”