Magnetic Resonance Studies of Deoxyribonucleoprotein

Bradbury, E. Morton; Carpenter, Brian; Rattle, H. W. E.

doi:10.1038/241123a0

Cited by 171 publications

(47 citation statements)

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“…1 , The densitometer scans were retraced and the areas under the curves were cut and weighed to obtain relative amounts of the histone fraction. The resul; were expressed as mean percentage k standard error from 10 independent isolations of whole chromatin and 5 independent isolations of tRNA- 131 histone has been shown by several authors [2, 3,8]. Consistent with these reports, the solubility of saltextracted chromatin (i.e., HI-depleted chromatin extracted in 0.6 M NaCI) (Fig.…”

Section: Resultssupporting

confidence: 73%

“…Furthermore, Bradbury et al [3] reported that chromatin gel contracted in 0.15 M NaCl to about 15 2, of its original volume. Salt extraction of HI histone caused the contracted gel to relax to its original volume.…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

“…But the function of H1 histone in chromatin is evidently distinct from that of the other histones. By analyzing selectively dehystonized chromatin it has been suggested that H1 histone is responsible for chromatin contraction and precipitation in 0.1 5 M NaCl [2,3] as well as for the cross-linking of chromatin fibers that results in massive condensation such as heterochromatization [4-61. However, the extraction of H1 histone is usually accompanied by the removal of considerable portion of non-histone proteins [7-101. Since the techniques used to remove H1 histone also result in a loss of nonhistone proteins, it is difficult to ascribe changes in properties of H1 -depleted chromatin purely to the loss of histone H1. It is generally believed that non-histone (EC 2.7.7.6).…”

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Changes in Chromatin Properties after Partial Extraction of Non‐histone Proteins

Bokhon'ko

Razumova²

1978

European Journal of Biochemistry

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By treatment with tRNA in the presence of 1 mM MgC12, a chromatin preparation was obtained containing all five major histone fractions but lacking a considerable portion of non-histone proteins. This chromatin preparation as well as chromatin extracted with 0.6 M NaCl (depleted of H1 histone and some non-histone proteins) were characterized in respect of solubility and chromatin DNA accessibility.Both samples possessed practically the same solubility in the presence of 0.15 M NaCl and 1 mM MgC12. The solubility of tRNA-treated chromatin in 5 and 10 mM MgClz was higher than that of salt-extracted chromation.The accessibility of the DNA of these chromatin preparations was tested with DNA-dependent RNA polymerase of Escherichia coli as a probe, using procedure that permits measurement of binding site frequency. Both tRNA-treated and salt-extracted chromatin contained as many as 33 '%, and untreated chromatin as few as 4 ;/; of the number of binding sites found on protein-free DNA.These results demonstrate that at least in part the non-histone proteins are responsible for saltinduced insolubility and low DNA accessibility of chromatin, thus revealing the importance of nonhistone proteins in the maintainance of an overall Chromatin structure.The precise role played by histones and nonhistone protein in the structure and function of chromatin is still not clear. Morphological and biochemical evidence strongly supports the concept that the four small histones form the structural repeating unit of chromatin : the nucleosome (for review see [l]). But the function of H1 histone in chromatin is evidently distinct from that of the other histones. By analyzing selectively dehystonized chromatin it has been suggested that H1 histone is responsible for chromatin contraction and precipitation in 0.1 5 M NaCl [2,3] as well as for the cross-linking of chromatin fibers that results in massive condensation such as heterochromatization [4-61.However, the extraction of H1 histone is usually accompanied by the removal of considerable portion of non-histone proteins [7-101. Since the techniques used to remove H1 histone also result in a loss of nonhistone proteins, it is difficult to ascribe changes in properties of H1 -depleted chromatin purely to the loss of histone H1. It is generally believed that non-histone (EC 2.7.7.6).proteins play an important role in regulating transcription of DNA [l]. Moreover, recently Ide et al. [I 11 have shown that non-histone proteins participated in supercoiled folding of chromatin DNA. Therefore, it would be of interest to examine the influence of selective removal of some non-histone proteins on the properties of chromatin.In this paper we describe the preparation of chromatin in which only part of the non-histone proteins was removed without the loss of five major histone fractions. The structural properties of this chromatin preparation as well as of 0.6 M NaCI-extracted chromatin (depleted of H1 histone and some non-histone proteins) are characterized in respect of solubility and chromatin DNA ...

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Section: Resultssupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Changes in Chromatin Properties after Partial Extraction of Non‐histone Proteins

Bokhon'ko

Razumova²

1978

European Journal of Biochemistry

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“…In this respect, a recently proposed model for chromatin structure [ l ] considers that this histone is not involved in the core of its globular subunits [ 2 , 3 ] . On the other hand there is evidence supporting the view that the presence of histone Hl is a basic requirement for the packing of DNA within the nucleoprotein [4]. In this context, modification 'in vivo' of a few residues of this histone seems to be related to the changes in chromatin contraction before mitosis [5].…”

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confidence: 55%

Studies on the Role and Mode of Operation of the Very‐Lysine‐Rich Histones in Eukaryote Chromatin

Puigdoménech

Martı́nez

Cabré

et al. 1976

European Journal of Biochemistry

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Proton magnetic resonance and other measurements have been carried out in order to study the behaviour of the lysine-rich histones cp 1 in the sperm chromatin of certain marine invertebrates. Well defined particles (12 S) have been obtained from this chromatin by nuclease treatment. Chromatin solubility as a function of ionic strength shows a relaxation at salt concentrations higher than in the case of calf thymus nucleoprotein. Nuclear magnetic resonance (NMR) studies show that the release of histone from DNA occurs both in chromatin and in the reconstituted complexes at practically the same ionic strength as solubility relaxation. The higher the arginine content of a given q 1, the higher the ionic strength at which both effects take place. The NMR results demonstrate that arginine residues are bound more strongly than lysine residues. The data overall show that the q 1 histones play a role in the contraction mechanism of sperm chromatin similar to that of H 1 histone in calf thymus chromatin. The highly contracted state of sperm chromatin is directly related to the increased arginine content of the cp 1 histone.Histone H1 appears to play an important role in the control of the structure of chromatin. In this respect, a recently proposed model for chromatin structure [ l ] considers that this histone is not involved in the core of its globular subunits [ 2 , 3 ] . On the other hand there is evidence supporting the view that the presence of histone Hl is a basic requirement for the packing of DNA within the nucleoprotein [4]. In this context, modification 'in vivo' of a few residues of this histone seems to be related to the changes in chromatin contraction before mitosis [5]. Studies on calf thymus chromatin including high-resolution NMR [4,6] have shown that the release of histone H1 is accompanied by a relaxation effect of contracted chromatin. In addition H1-depleted chromatin does not show the typical conl-raction behaviour of chromatin with an increase of salt concentration [4].Sperm chromatin is a highly condensed material, packed within the spermatozoa head. The X-ray diffraction patterns of sperm nucleohistone show only slight differences among different species [7]. It is also -~ ~~ Abbreviutit?n. NMR, nuclear magnetic resonance well known that the basic proteins bound to sperm DNA are very different in different species, and in echinoderms they are closely related to somatic histones; in sea urchin sperm, for instance, the five typical fractions are found, with some modifications in amino acid composition when compared with calf thymus histones [8].The H1-like histones extracted from the sperm of some echinoderms and molluscs, called histones cp 1, show a number of differences in their amino acid composition with respect to calf thymus H1. Notable is a greater arginine content in most cpl histones. The cpl histones used in the present work were extracted from the sea urchins Arhacia lixula and Paracentrotus lividus, the sea cucumber Holothuria tubulosa, and the sea mussel Mytilus eddis. NMR studies ...

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

Wellman¹

1998

Biopolymers

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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.

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Magnetic Resonance Studies of Deoxyribonucleoprotein

Cited by 171 publications

References 14 publications

Changes in Chromatin Properties after Partial Extraction of Non‐histone Proteins

Changes in Chromatin Properties after Partial Extraction of Non‐histone Proteins

Studies on the Role and Mode of Operation of the Very‐Lysine‐Rich Histones in Eukaryote Chromatin

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

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