The stepwise removal of histones from chicken erythrocyte nucleoprotein

Murray, Kenneth; Vidali, G.; Neelin, J. M.

doi:10.1042/bj1070207

Cited by 113 publications

(33 citation statements)

References 20 publications

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“…Chicken erythrocyte nuclei were isolated by the procedure of Murray et al [21]. Chicken blood was collected in 10% citrate buffer and transported on ice.…”

Section: Multimer Preparationmentioning

confidence: 99%

Higher‐Order Structures of Chromatin in Solution

Suau

Bradbury

Baldwin

1979

European Journal of Biochemistry

168

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Neutron scatter studies have been made on gently prepared chicken erythrocyte chromatin over a range of ionic strength. At low ionic strength the mass per unit length of the '10-nm' nucleofilament corresponds to one nucleosome per 8 -12 nm and a DNA packing ratio of between 6 and 9. From the contrast dependence of the cross-section radius of gyration of the nucleofilament the following parameters have been obtained; RgDNA, the cross-section radius of gyration (R,) when DNA dominates the scatter; RgP, the cross-section R, when protein dominates the scatter; R,, the cross-section R, at infinite contrast and a, the constant which describes the dependence of the cross-section R, on contrast variation. From our understanding of the structure of the core particle, various arrangement of core particles in the nucleofilament have been tested. In models consistent with the above parameters the core particles are arranged edge-to-edge or with the faces of the core particles inclined to within 20* to the axis of the nucleofilament. With increase of ionic strength the transition to the second-order chromatin structure has been followed. This gave the interesting result that above 20 mM NaCl or 0.4 mM MgCI2 the cross-section R, increases abruptly to about 9 nm with a packing ratio of 0.2 nucleosome/nm and with further increase of ionic strength the R, increases to 9.5 nm while the packing ratio increases threefold to 0.6 nucleosome/nm. This suggests a family of supercoils of nucleosomes which contract with increasing ionic strength. In its most contracted form the diameter of the hydrated supercoil has been found from the radial distribution function to be 34 nm. Models for the arrangements of core particles in the 34-nm supercoil are discussed.There is now growing evidence that the DNA in metaphase chromosomes and in the interphase nucleus is organised into discrete loops which contain some 30000-90000 basepairsofDNA [1,2]or inchromatin domains of average size 34000 bases of DNA [3,4]. The DNA of these domains or loops when complexed with chromosomal proteins in inactive regions of chromatin and in metaphase chromosomes is highly compacted and several orders of chromatin structure must exist above the linear array of nucleosomes.In the electron microscope chromatin has been visualised as fibrils of different diameters. At low ionic strength the fibrils have a diameter of about 10 nm [5-81. On the addition of monovalent or divalent cations a transition to a higher-order structure is observed and the diameter of the fibril increases to 25 -30 nm IS, 9 -131. From electron microscopy studies a solenoid model has been proposed [ 121 which consists of the 10-nm fibril or nucleofilament coiled with a pitch of 11 nm and a diameter of 30 nm. It has also been shown that the 10-1 I-nm semimeridional arc in the neutron diffraction of H 1 -depleted chromatin [14] and of total chromatin fibres [15] contain maxima which are located off the meridian and these observations have been explained by a coil model with similar parameters. This ty...

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“…Chicken erythrocyte nuclei were isolated by the procedure of Murray et al [21]. Chicken blood was collected in 10% citrate buffer and transported on ice.…”

Section: Multimer Preparationmentioning

confidence: 99%

Higher‐Order Structures of Chromatin in Solution

Suau

Bradbury

Baldwin

1979

European Journal of Biochemistry

168

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“…It has even been suggested [31] that histones F1 (Hl) and F2c (H5) are related in evolution. Both of these histones are more easily removed from chromatin than the other histones and neither are needed to maintain the supercoiled structure of native nucleoprotein [7,32,33]. It has been suggested by Bradbury et al that the two ends of each F1 (Hl) molecule are bound to the DNA in chromatin whereas the central segment of the histone molecule has two conformations, producing dispersed chromatin and condensed chromatin respectively [34].…”

Section: Discussionmentioning

confidence: 99%

“…The collection was made in 400-500-ml lots into buckets containing 50 ml of 10 % (wiv) trisodium citrate and the blood was then transported as quickly as possible to the laboratory where the erythrocytes were sedimented in a refrigerated centrifuge at 4 "C. Nucleohistone was prepared according to the method of Murray et al [7], and the preparation of the individual chicken erythrocyte histone fractions was carried out in collaboration with Dr E. W. Johns [30].…”

Section: Methodsmentioning

confidence: 99%

The Self‐Association of Chicken‐Erythrocyte Histones

Diggle

McVITTIE

Peacocke

1975

European Journal of Biochemistry

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The self-association of the separate histone fractions isolated from chicken erythrocytes has been studied in solution at a number of different pH values and ionic strengths. The apparent molecular weights of the histones were determined over a range of macromolecular concentrations using the techniques of osmotic pressure and sedimentation equilibrium. Histone F2c (H5) did not associate under any of the conditions investigated whereas the other histone fractions all appeared to undergo self-association forming dimers, dimers of dimers, etc. The degree of association increased with the pH and ionic strength of the medium. The tendency to aggregate increased in the order; histone F2c (H5) (non-aggregating), histone F2b (H2B), histone F2a2 (H2A), histone F3 (H3), histone F2al (H4) (highly aggregating).In the case of histone F2a2 (H2A) at pH 3.0 and ionic strength 0.1, the apparent weight-average molecular weight was determined at a number of macromolecular concentrations at five different temperatures. The self-association was analysed according to the method of Adams (published by Beckman Instruments Inc. in 1967) and shown to be a monomer-dimer-tetramer equilibrium. The association constants were evaluated at each of the temperatures studied and from their variation with temperature the values of the enthalpy and entropy of association were calculated. The intermolecular association was characterised by only a small change in enthalpy but a large, positive, change in entropy. This suggests that the association of histones at acid pH is due to hydrophobic interactions between the relatively uncharged segments of like polypeptide chains.Several lines of evidence have implicated the histones in the maintenance of the structural and functional integrity of the chromosome (see, e.g. Crick [2]). The amino-acid sequences have shown that all of the histone fractions possess a marked asymmetric distribution of the basic amino acids. It is suggested by Huberman [3] that the positively charged, basic residues of the histone molecule are associated with the negatively charged DNA-phosphates in nucleohistone, and that non-covalent interactions between the non-basic segments of the histone molecules are responsible for maintaining chromatin in its supercoil configuration. Such interactions could be intermolecular or intramolecular. Isolated histones in solution tend to aggregate [4,5] and it is possible that this aggregation is a result of histone-histone interactions of the type normally responsible for maintaining correct chromosomal structure.We present here the results of an investigation of the factors influencing the aggregation of isolated histone fractions in solution. The variation of the apparent molecular weights of the histone fractions with concentration, pH and ionic strength was first studied and has been published in summary already [6]. It was apparent that the analytical procedures of Adams [l] could be applied to such osmotic pressure and sedimentation results to obtain a measure of the stoichiometry and e...

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“…The resultant homogenates were left at o "C overnight in order to extract completely all ribosomal and soluble proteins. The homogenates were centrifuged at 200g for 10 min, the supernatant liquid was removed, and the pellets were resuspended in 2 ml acetate buffer, pH 2.2, and left for 2 h at o "C. Thereafter, the other fractions were obtained by serial extraction as previously described (Murray et al 1968) by using 2 ml volumes of the appropriate buffers. The amount of proteins in the extracts was measured by determining the extinction at 260 and 2801 nm (Warburg & Christian, 1941).…”

Section: Methodsmentioning

confidence: 99%

Stepwise Accumulation of an Acid-extractable Protein Fraction in the Budding Yeast, Kluyveromyces fragilis, during the Cell Cycle

Duffus¹,

Penman²

1973

Journal of General Microbiology

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S U M M A R YAcid-extractable proteins were obtained from Kluyveromyces fragilis by pH titration, and partially characterized. They differ from mammalian histones and from the proteins obtained from other yeasts by similar methods. The largest fraction, extracted at pH 2-2, appeared to be predominantly of cytoplasmic origin. Quantitative changes in this fraction have been followed through the cell cycle and mapped relative to DNA synthesis, nuclear division and cell division. The total amount of such protein/cell doubled about one-third of a cycle after cell division and at a quarter of a cycle before nuclear division. DNA synthesis did not correspond to these doubling times but was almost simultaneous with cell division.

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The stepwise removal of histones from chicken erythrocyte nucleoprotein

Cited by 113 publications

References 20 publications

Higher‐Order Structures of Chromatin in Solution

Higher‐Order Structures of Chromatin in Solution

The Self‐Association of Chicken‐Erythrocyte Histones

Stepwise Accumulation of an Acid-extractable Protein Fraction in the Budding Yeast, Kluyveromyces fragilis, during the Cell Cycle

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