Linker Histones (linker + histone)

Distribution by Scientific Domains


Selected Abstracts


Chromatin dynamics of unfolding and refolding controlled by the nucleosome repeat length and the linker and core histones

BIOPOLYMERS, Issue 4 2007
Toshiro Kobori
Abstract Chromatin is composed of genomic DNA and histones, forming a hierarchical architecture in the nucleus. The chromatin hierarchy is common among eukaryotes despite different intrinsic properties of the genome. To investigate an effect of the differences in genome organization, chromatin unfolding processes were comparatively analyzed using Schizosaccaromyces pombe, Saccharomyces cerevisiae, and chicken erythrocyte. NaCl titration showed dynamic changes of the chromatin. 400,1000 mM NaCl facilitated beads with ,115 nm in diameter in S. pombe chromatin. A similar transition was also observed in S. cerevisiae chromatin. This process did not involve core histone dissociation from the chromatin, and the persistence length after the transition was ,26 nm for S. pombe and ,28 nm for S. cerevisiae, indicating a salt-induced unfolding to "beads-on-a-string" fibers. Reduced salt concentration recovered the original structure, suggesting that electrostatic interaction would regulate this discrete folding-unfolding process. On the other hand, the linker histone was extracted from chicken chromatin at 400 mM NaCl, and AFM observed the "beads-on-a-string" fibers around a nucleus. Unlike yeast chromatin, therefore, this unfolding was irreversible because of linker histone dissociation. These results indicate that the chromatin unfolding and refolding depend on the presence and absence of the linker histone, and the length of the linker DNA. © 2007 Wiley Periodicals, Inc. Biopolymers 85:295,307, 2007. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]


Development of H1e histone linker-specific antibodies by means of synthetic peptides

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2004
K. Foulon
Abstract:, A large body of data suggests that the linker histones family (H1) affects gene expression. Investigation of the linker histones role is then of a major interest in cell cycle studies with implications in gene therapy. Indeed, it has been shown that in most tissues a switch of histone subtypes occurs when the cells cease to divide. To investigate linker histone role in gene or transgene expression, an antibody against subtypes of H1 would be useful for immunoprecipitation experiments and further assays measuring H1subtypes,DNA interactions in living cells. In order to produce an antibody against the H1e subtype of linker histones, two synthetic peptides derived from two regions of the H1e mouse histone protein were examined for their potential, [as keyhole limpet hemocyanin (KLH) conjugates] to elicit polyclonal anti-H1e antibodies in New Zealand white rabbits. Selection of the peptide sequences was based on amino acid differences within the different classes of histones and between mice and rabbit histones as well. The evaluation of their potential immunogenic properties was based on examination of peptide hydropathy using predicting algorithms. Immunoglobulins (IgG) obtained from immunized and nonimmunized rabbits were tested using enzyme-linked immunosorbent assay (ELISA) procedures, Western immunoblot, and immunofluorescence experiments. Results showed that the selected synthetic peptides gave rise to a high-titer polyclonal antibody able to recognize the H1e histone under various conditions. This polyclonal antibody did not cross-react with other histones. To our knowledge, this is the first antibody produced against the mouse H1e linker histone. [source]


A unique vertebrate histone H1-related protamine-like protein results in an unusual sperm chromatin organization

FEBS JOURNAL, Issue 19 2006
Núria Saperas
Protamine-like proteins constitute a group of sperm nuclear basic proteins that have been shown to be related to somatic linker histones (histone H1 family). Like protamines, they usually replace the chromatin somatic histone complement during spermiogenesis; hence their name. Several of these proteins have been characterized to date in invertebrate organisms, but information about their occurrence and characterization in vertebrates is still lacking. In this sense, the genus Mullus is unique, as it is the only known vertebrate that has its sperm chromatin organized by virtually only protamine-like proteins. We show that the sperm chromatin of this organism is organized by two type I protamine-like proteins (PL-I), and we characterize the major protamine-like component of the fish Mullus surmuletus (striped red mullet). The native chromatin structure resulting from the association of these proteins with DNA was studied by micrococcal nuclease digestion as well as electron microscopy and X-ray diffraction. It is shown that the PL-I proteins organize chromatin in parallel DNA bundles of different thickness in a quite distinct arrangement that is reminiscent of the chromatin organization of those organisms that contain protamines (but not histones) in their sperm. [source]


Characterization of sequence variations in human histone H1.2 and H1.4 subtypes

FEBS JOURNAL, Issue 14 2005
Bettina Sarg
In humans, eight types of histone H1 exist (H1.1,H1.5, H1°, H1t and H1oo), all consisting of a highly conserved globular domain and less conserved N- and C-terminal tails. Although the precise functions of these isoforms are not yet understood, and H1 subtypes have been found to be dispensable for mammalian development, it is now clear that specific functions may be assigned to certain individual H1 subtypes. Moreover, microsequence variations within the isoforms, such as polymorphisms or mutations, may have biological significance because of the high degree of sequence conservation of these proteins. This study used a hydrophilic interaction liquid chromatographic method to detect sequence variants within the subtypes. Two deviations from wild-type H1 sequences were found. In K562 erythroleukemic cells, alanine at position 17 in H1.2 was replaced by valine, and, in Raji B lymphoblastoid cells, lysine at position 173 in H1.4 was replaced by arginine. We confirmed these findings by DNA sequencing of the corresponding gene segments. In K562 cells, a homozygous GCC,GTC shift was found at codon 18, giving rise to H1.2 Ala17Val because the initial methionine is removed in H1 histones. Raji cells showed a heterozygous AAA,AGA codon change at position 174 in H1.4, corresponding to the Lys173Arg substitution. The allele frequency of these sequence variants in a normal Swedish population was found to be 6.8% for the H1.2 GCC,GTC shift, indicating that this is a relatively frequent polymorphism. The AAA,AGA codon change in H1.4 was detected only in Raji cells and was not present in a normal population or in six other cell lines derived from individuals suffering from Burkitt's lymphoma. The significance of these sequence variants is unclear, but increasing evidence indicates that minor sequence variations in linker histones may change their binding characteristics, influence chromatin remodeling, and specifically affect important cellular functions. [source]


Development of H1e histone linker-specific antibodies by means of synthetic peptides

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2004
K. Foulon
Abstract:, A large body of data suggests that the linker histones family (H1) affects gene expression. Investigation of the linker histones role is then of a major interest in cell cycle studies with implications in gene therapy. Indeed, it has been shown that in most tissues a switch of histone subtypes occurs when the cells cease to divide. To investigate linker histone role in gene or transgene expression, an antibody against subtypes of H1 would be useful for immunoprecipitation experiments and further assays measuring H1subtypes,DNA interactions in living cells. In order to produce an antibody against the H1e subtype of linker histones, two synthetic peptides derived from two regions of the H1e mouse histone protein were examined for their potential, [as keyhole limpet hemocyanin (KLH) conjugates] to elicit polyclonal anti-H1e antibodies in New Zealand white rabbits. Selection of the peptide sequences was based on amino acid differences within the different classes of histones and between mice and rabbit histones as well. The evaluation of their potential immunogenic properties was based on examination of peptide hydropathy using predicting algorithms. Immunoglobulins (IgG) obtained from immunized and nonimmunized rabbits were tested using enzyme-linked immunosorbent assay (ELISA) procedures, Western immunoblot, and immunofluorescence experiments. Results showed that the selected synthetic peptides gave rise to a high-titer polyclonal antibody able to recognize the H1e histone under various conditions. This polyclonal antibody did not cross-react with other histones. To our knowledge, this is the first antibody produced against the mouse H1e linker histone. [source]