Irreversible Changes Occur in Chromatin Structure Upon Dissociation Of Histone H1

Hacques, Marie‐Françoise; Marion, Christian

doi:10.1080/07391102.1990.10507815

Cited by 5 publications

(2 citation statements)

References 64 publications

(97 reference statements)

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“…We have reported previously ( [24] and references cited therein) that native animal chromatin exhibits clearly positive birefringence (Fig. 2c), in contrast to the negative birefringence of DNA and nucleosomes (Fig.…”

Section: Electric-birefringence Propertiesmentioning

confidence: 85%

“…), as compared to that of rat liver or chicken erythocyte chromatin [12,23,241. Indeed, by assuming the values of Kerr's constant determined previously for the core particle and for H1-depleted nucleosomes [24], the amplitude of birefringence of 7: brucei brucei chromatin only corresponds to that of an H1-depleted rat liver nucleosome (-0.0715 e.s.u.). This means that, although i?…”

Section: Discussionmentioning

confidence: 99%

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Structural analysis of Trypanosoma brucei brucei chromatin by limited proteolysis

Michalon

Couturier

Bender

et al. 1993

European Journal of Biochemistry

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The sensitive electric-birefringence method was used to reveal structural differences between the soluble chromatin of procyclic Trypanosomu brucei brucei and the chromatin of the higher eukaryotes. The orientation of the nucleosomal chains and the presence of extended DNA were analysed from the sign and amplitude of the steady-state birefringence, and the conformational properties (overall dimensions and flexibility) were studied in relation to the orientational relaxation times.In contrast to the higher eukaryotes, the birefringence of I: brucei brucei is negative and of low amplitude, corresponding to that of H1-depleted rat liver nucleosomes. Furthermore, the relaxation times are very small, about 10 ps. If salt is added, the birefringence as well as the relaxation time decreases dramatically, indicating that condensation affects T brucei brucei chromatin although it behaves like nucleosome filaments, with less stable DNA-protein interaction than for the higher eukaryotes. However, this condensation does not induce the formation of regular higher-order stmcture. This complies with the hypothesis that typical histone H1 is absent from ir: brucei brucei chromatin and that a protein or protein domain fulfils the role of histone H1.The accessibility and structural role of histone-like proteins in 7: brucei brucei chromatin were also investigated using limited proteolysis with enzymes covalently bound to nylon spheres. The analysis of protein products obtained after digestion with immobilized trypsin and subtilisin shows that proteins a and d, which are classified as H3 and H4 histones, respectively, are the first to be attacked.The changes in chromatin conformation indicate that chromatin undergoes a structural transition, leading to decondensation, as indicated by increases in negative birefringence and relaxation time, and to a change in its orientation mechanism, indicated by the appearance of a permanent moment.This result is very interesting since, in rat liver, H4 was very resistant and was the last histone to be attacked, suggesting internal location and its involvement in nucleosome stabilization rather than higher-order condensation.Therefore, in i ? brucei brucei chromatin, the characteristic properties of proteins a and d (their composition and interaction with DNA), as well as their external location on the nucleosome surface, suggest that if these proteins play a role similar to that played by H3 and H4 in higher eukaryotes, probably through their N-terminal regions and interaction either with DNA or protein domains, the mechanisms involved in chromatin compaction are quite different. Since there is no binding with H1, it may be hypothesized that a (non-histone) protein, or core protein domains, may play a part in chromatin compaction and gene expression regulation comparable to that of H1 in higher eukaryotes.

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Section: Electric-birefringence Propertiesmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Structural analysis of Trypanosoma brucei brucei chromatin by limited proteolysis

Michalon

Couturier

Bender

et al. 1993

European Journal of Biochemistry

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A Method for Efficient Extraction of Bovine Papilloma Virus-Based Minichromosomes that Preserves Native Chromatin Structure

Карпова

Tchirkova²,

Vorobiev³

et al. 1999

DNA and Cell Biology

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Aiming to create an adequate model for investigation of the molecular mechanisms involved in transcriptional regulation by steroid hormones, a number of cell lines carrying bovine papilloma virus (BPV) based constructs containing the mouse mammary tumor virus long terminal repeat (LTR) were established (Ostrowski et al., Mol. Cell. Biol. 3, 2945-2957, 1983). However, all our attempts to extract from the cells such minichromosomes as nucleoprotein complexes using a method previously described (Ostrowski, Nucleic Acids Res. 15, 6957-6971, 1987) failed. Here, we show that this failure was attributable to DNA rearrangements in most of the cell lines, resulting in the integration of the BPV-based constructs into the host cell genome. We have identified two cell lines where the constructs are episomal. Micrococcal nuclease digestion of the nuclei demonstrated the presence of nucleosomes positioned over the episomal MMTV LTR. We managed to optimize conditions for preparation of nuclei and minichromosomes, which allowed extraction of approximately 40% of the minichromosomes, most of them being in circular superhelical form. Our data show clearly that the main factor preventing the release of minichromosomes from the nuclei is the presence of polyamines in the cell lysis buffer. The organization of MMTV promoter chromatin was unaffected by the extraction procedure, suggesting that these minichromosomes could be valuable templates for in vitro transcription studies and to identify proteins involved in chromatin remodeling during transcription.

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Changes in chromatin structure associated with germination of maize and their relation with desiccation tolerance

Leprince

Colson

Houssier

et al. 1995

Plant Cell & Environment

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Morphological and physicochemical measurements of chromatin condensation were made on germinating maize (Zea mays L.) radicles to determine whether the loss of genetic activities that occurs during the loss of desiccation tolerance is linked to irreversible changes in chromatin condensation. Chromatin samples were compared at different stages of germination (0, 24 and 72 h after imbibition), before (control) and after 24 h of desiccation. Morphological changes in chromatin structure and condensation were characterized by a qualitative and quantitative electron microscope study of chromatin which was allowed to spread in 0.2 mol m−3 EDTA and then laid on coated microscope grids. The experiments showed similar levels of chromatin condensation in quiescent embryos and 24‐h‐old radicles (desiccation‐tolerant material). After 72 h of imbibition, when radicle emergence and desiccation intolerance had ceased, the chromatin underwent a major decondensation towards various lower order folded structures. Regardless of the desiccation tolerance stage, an in vivo drying treatment of 24‐ and 72‐h‐old radicles before chromatin extraction did not induce significant changes in the extent of condensation compared to their respective controls. Similar conclusions were drawn from measurements of several spectroscopy properties (absorbance ratios: A260/A240, A260/A400; thermal denaturation, and linear electric dichroism) of chromatin fragments that were obtained after nuclease digestion and then dissolved in 0‐2 mol m−3 EDTA. In quiescent and 24‐h‐old material, chromatin fragments were poorly soluble but highly stable during thermal denaturation. Chromatin fragments were 3‐5‐fold more soluble and less thermally stable in 72‐h‐old material than in 24‐h‐old material. In vivo desiccation had no significant effects on these properties compared to the respective controls. Collectively these data suggest that desiccation did not induce irreversible changes in the condensation properties of chromatin. The likelihood that the decondensation process occurring during germination is linked to the loss of desiccation tolerance is discussed.

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Irreversible Changes Occur in Chromatin Structure Upon Dissociation Of Histone H1

Cited by 5 publications

References 64 publications

Structural analysis of Trypanosoma brucei brucei chromatin by limited proteolysis

Structural analysis of Trypanosoma brucei brucei chromatin by limited proteolysis

A Method for Efficient Extraction of Bovine Papilloma Virus-Based Minichromosomes that Preserves Native Chromatin Structure

Changes in chromatin structure associated with germination of maize and their relation with desiccation tolerance

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