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Johnson WC. Circular dichroism and its empirical application to biopolymers. METHODS OF BIOCHEMICAL ANALYSIS 2006; 31:61-163. [PMID: 3894885 DOI: 10.1002/9780470110522.ch2] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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2
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Rexroad J, Wiethoff CM, Green AP, Kierstead TD, Scott MO, Middaugh CR. Structural stability of adenovirus type 5. J Pharm Sci 2003; 92:665-78. [PMID: 12587128 DOI: 10.1002/jps.10340] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Thermally induced structural changes in adenovirus type 5 (Ad) in the presence of either 2 or 10% sucrose were investigated using a variety of biophysical techniques. In solutions containing 2% sucrose, a highly cooperative transition in the structure of the virus was observed at 45 degrees C as detected by tryptophan fluorescence, derivative UV absorption spectroscopy, circular dichroism (CD), and dynamic and static light scattering. This transition resulted in (at least partial) disassembly of the virus and a concomitant increase in the accessibility of the viral DNA to the fluorescent dye, TOTO-1. Capsid disassembly was verified by transmission electron microscopy, which showed ruptured icosahedral vertices near 45 degrees C followed by complete capsid disassembly at higher temperatures. SDS-PAGE of thermally treated Ad suggests that the penton base (protein III) and protein IIIa (located in the peripentonal region) are significantly more labile than other capsid proteins and may be the initial instigators in capsid disassembly. Additional discrete structural transitions were observed in viral proteins using the aforementioned spectroscopic techniques. Thermally induced rearrangements of the condensed DNA at higher temperatures were also detected by the appearance of "psi"-like features in the CD spectra as well as a dramatic decrease in accessibility of DNA to TOTO-1. These transitions corresponded to discrete endothermic events that are also detected by differential scanning calorimetry. By increasing the concentration of sucrose to 10%, secondary and tertiary structural features of adenoviral proteins were significantly stabilized, although loss of quaternary structure at 45 degrees C was still observed.
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Affiliation(s)
- Jason Rexroad
- Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Ave., Lawrence, KS 66047, USA
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3
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Fredericq E, Hacha R, Colson P, Houssier C. Condensation and precipitation of chromatin by multivalent cations. J Biomol Struct Dyn 1991; 8:847-65. [PMID: 2059343 DOI: 10.1080/07391102.1991.10507849] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The condensation and the precipitation of rat liver chromatin upon addition of spermine4+, spermidine3+, hexamminecobalt(III)3+ and Mg2+ cations have been studied using solubility, fluorescence, circular dichroism, melting curves, electric dichroism and spermidine binding measurements, made on both soluble and precipitated complexes. The soluble complexes obtained with tetra- and trivalent cations were depleted from all histones and enriched in other proteins, particularly high mobility group proteins 1 and 2, which brings about an important enhancement of tryptophan fluorescence without modification of its two lifetimes 5.1 and 1.2 ns. In the precipitates the non-histone proteins are eliminated. Under precipitation by Mg2+ ions, the distribution of proteins remains practically unchanged. The electric dichroism and the melting curves indicate that the soluble complexes between polyamines and chromatin undergo important condensation and, at high ratios of cation over phosphate, are constituted by heterogeneous assemblies of non-histone proteins and DNA. On the contrary, the insoluble complexes seem to retain the main features of original chromatin. Precipitation by Mg2+ ions reveal much less drastic changes than those produced by polyamines. Precipitation by spermidine occurs when one cation is bound per eight nucleotides, which in addition to the histone positive charges brings about a complete neutralization of chromatin phosphates.
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Affiliation(s)
- E Fredericq
- Laboratorie de Chimie Macromoléculaire et Chimie Physique, Université de Liège, Belgium
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4
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Erard MS, Belenguer P, Caizergues-Ferrer M, Pantaloni A, Amalric F. A major nucleolar protein, nucleolin, induces chromatin decondensation by binding to histone H1. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 175:525-30. [PMID: 3409881 DOI: 10.1111/j.1432-1033.1988.tb14224.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Using circular dichroism to probe the extent of DNA condensation in chromatin, we have demonstrated that a major nucleolar protein, nucleolin can decondense chromatin. By means of various binding assays we show that nucleolin has a strong affinity for histone H1 and that the phosphorylated N-terminal domain, rich in lengthy stretches of acidic amino acids, is responsible for this ionic interaction. Additional experiments clearly demonstrate that nucleolin is unable to act as a nucleosome core assembly or disassembly factor and hence has little affinity for the core histone octamer. We propose that this nucleolar protein induces chromatin decondensation by binding to histone H1, and that nucleolin can therefore be regarded as a protein of the high-mobility-group type.
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Affiliation(s)
- M S Erard
- Centre de Recherche de Biochimie et de Génétique Cellulaires du CNRS, Toulouse, France
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5
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Fredericq E, Hacha R, Houssier C. Condensation of chromatin films in contact with divalent cation solutions at physiological ionic strength. Int J Biol Macromol 1988. [DOI: 10.1016/0141-8130(88)90067-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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6
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Oohara I, Wada A. Spectroscopic studies on histone-DNA interactions. II. Three transitions in nucleosomes resolved by salt-titration. J Mol Biol 1987; 196:399-411. [PMID: 3656451 DOI: 10.1016/0022-2836(87)90700-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The multiple-step transitions in DNA-histone interactions in chicken erythrocyte nucleosomes with increasing ionic strength are resolved by salt-titration spectroscopy. Both the circular dichroism of the DNA and the fluorescence of the histones in nucleosomes change during the titration process with concentrations of NaCl from 0.1 M to 2.5 M. By differentiating the titration curves, three distinct peaks corresponding to three structural transitions are observed. The two peaks near 0.95 M and 1.45 M-NaCl are common to the circular dichroism and fluorescence curves. The circular dichroism curve has another peak near 0.55 M-NaCl. Because the derivative of the fluorescence titration curve for the DNA-(H3, H4) complex has only one peak near 1.45 M-NaCl, that peak is attributed to the dissociation of the histone dimer (H3, H4). The peak near 0.95 M-NaCl corresponds to the dissociation of the dimer (H2A, H2B) from the DNA-(H3, H4) complex, as shown by binding experiments of (H2A, H2B) to the DNA-(H3, H4) complex at the salt concentration near this peak. The peak near 0.55 M-NaCl reflects some inner-core structural change. As the change of the circular dichroism signal is reversible, salt-titration spectroscopy is applicable to equilibrium studies of the physical chemical properties of DNA-histone interactions. By the assumption of a non-co-operative model, the binding constant for the chicken erythrocyte (H2A, H2B) dimer to the DNA-(H3, H4) complex is calculated as 2.8 X 10(6) M-1 at 1.0 M-NaCl (20 degrees C, pH 7.6). The DNA sequence dependence of the stability of the DNA-(H3, H4) interaction is observed in the salt-titration profiles of reconstituted material. Decreasing stability of the interaction of (H3, H4) is observed following the order: poly[(dG)-(dC)] much greater than chicken erythrocyte DNA greater than poly[(dA)-(dT)]. It is concluded that histones (H3, H4) have a different DNA sequence dependence from histones (H2A, H2B).
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Affiliation(s)
- I Oohara
- Department of Physics, Faculty of Science, University of Tokyo, Japan
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7
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Stone GR, Baldwin JP, Carpenter BG. Polyamines permit the preparation of stable Physarum core particles which have a structure similar to those from higher eukaryotes. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 908:34-45. [PMID: 3801484 DOI: 10.1016/0167-4781(87)90019-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The inherent instability of Physarum nucleosome core particles prepared by micrococcal nuclease digestion in Na+/Ca2+ buffers can be overcome by the addition of 0.15 mM spermine and 0.5 mM spermidine. Neutron scattering, circular dichroism, nuclease digestion and thermal denaturation studies carried out on these stable monosomes show them to be very similar to those obtained from higher eukaryotes.
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8
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Marquet R, Colson P, Houssier C. The condensation of chromatin and histone H1-depleted chromatin by spermine. J Biomol Struct Dyn 1986; 4:205-18. [PMID: 3271439 DOI: 10.1080/07391102.1986.10506340] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
At low ionic strength, spermine induces aggregation of native and H1-depleted chromatin at spermine/phosphate (Sp/P) ratios of 0.15 and 0.3, respectively. Physico-chemical methods (electric dichroism, circular dichroism and thermal denaturation) show that spermine, at Sp/P less than 0.15, does not appreciably alter the conformation of native chromatin and interacts unspecifically with all parts of chromatin DNA (linker as well as regions slightly or tightly bound to histones). In chromatin, the role of spermine could be more important in the stabilization of higher-order structure than in the condensation of the 30 nm solenoid. The addition of spermine to H1-depleted chromatin revealed two important features: (i) spermine can partially mimic the role of histone H1 in the condensation of chromatin; (ii) the core histone octamer does not appear to play any role in the aggregation process by spermine as DNA and H1-depleted chromatin aggregate at the same Sp/P ratio.
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Affiliation(s)
- R Marquet
- Laboratoire de Chimie Macromoléculaire et Chimie Physique Université de Liège, Belgium
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9
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Mithieux G, Roux B, Rousset B. Tubulin-chromatin interactions: evidence for tubulin-binding sites on chromatin and isolated oligonucleosomes. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 888:49-61. [PMID: 3741889 DOI: 10.1016/0167-4889(86)90070-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The interaction of tubulin with chromatin has been studied using a radiolabeled tubulin binding assay and velocity sedimentation analysis on isokinetic sucrose gradients. Soluble chromatin was prepared by mild micrococcal nuclease digestion of rat liver nuclei and tubulin was purified from rat brain by temperature-dependent assembly-disassembly and phosphocellulose chromatography. The tubulin-binding assay is based on the ability of chromatin to precipitate quantitatively at physiological ionic strength allowing separation of free tubulin from chromatin-bound tubulin. The binding of tubulin to unfractionated soluble chromatin was rapid, reversible and saturable. Saturation of binding sites was obtained using tubulin concentrations ranging from 0.5 to 400 micrograms/ml, in the presence of a high concentration (2.5 mg/ml) of another acidic protein, bovine serum albumin. The Scatchard and Hill plots showed that tubulin bound to a single class of non-interacting sites and yielded values of (0.5-0.6) X 10(7) M-1 for an apparent Ka and a maximal binding capacity of 0.8 nmol tubulin/mg DNA, i.e. about 1 molecule of tubulin/10 nucleosomes. Similar binding parameters were obtained when binding experiments were performed with insoluble chromatin in 0.15 M NaCl. Velocity sedimentation analysis of tubulin-chromatin complexes revealed that tubulin bound to all classes of chromatin oligomers, irrespective of the length of the nucleosomal chain. Tubulin-trinucleosome complexes formed from isolated trinucleosome in the presence of an excess of tubulin were separated from free reactants. It was found that 10-15% of the starting oligonucleosomal species reacted with tubulin, in a stoichiometry of about 0.8 molecule of tubulin/nucleosome. Given the characteristics of the binding and the expected cellular free tubulin concentration, the tubulin-chromatin interaction could possibly take place in vivo, when the nuclear membrane breaks down during the first steps of mitosis.
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10
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Calascibetta FG, De Santis P, Morosetti S, Savino M, Scipioni A. DNA topology in a chromatin model system. CELL BIOPHYSICS 1986; 8:177-88. [PMID: 2425975 DOI: 10.1007/bf02788493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The synthetic copolypeptide (Lys33, Leu67)100-Orn20, modeled on some general features of the histone sequences, has been found to supercoil the DNA double helix, wrapping it into a micelle, as a result of cohesive interactions between the polypeptide hydrophobic moieties. X-ray low-angle diffraction of complexes between the polypeptide and DNA is characterized by maxima at 50, 32, and 23 A, reminiscent of the chromatin pattern. The existence of a nucleosome-like structure along the DNA is suggested by gel electrophoresis analysis of DNA fragments after micrococcal nuclease digestion, showing the presence of a fragment of about 100 basepairs (bp) long. Topological experiments on the complexes with supercoiled as well as relaxed circular DNA by two-dimensional gel electrophoresis show the presence of left-handed superhelical turns. The results are in agreement with an intrinsic propensity of B-DNA to writhe into left-handed supercoils.
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11
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Marion C, Hesse-Bezot C, Bezot P, Marion MJ, Roux B, Bernengo JC. The effect of histone H1 on the compaction of oligonucleosomes. A quasielastic light scattering study. Biophys Chem 1985; 22:53-64. [PMID: 4027333 DOI: 10.1016/0301-4622(85)80025-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The structural properties of H1-depleted oligonucleosomes are investigated by the use of quasielastic laser light scattering, thermal denaturation and circular dichroism and compared to those of H1-containing oligomers. To obtain information on the role of histone H1 in compaction of nucleosomes, translational diffusion coefficients (D) are determined for mono-to octanucleosomes over a range of ionic strength. The linear dependences of D on the number of nucleosomes show that the conformation of stripped oligomers is very extended and does not change drastically with increasing the ionic strength while the rigidness of the chain decreases due to the folding of linker DNA. The results prove that the salt-induced condensation is much smaller for H1-depleted than for H1-containing oligomers and that histone H1 is necessary for the formation of a supercoiled structure of oligonucleosomes, already present at low ionic strength.
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12
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Ashikawa I, Kinosita K, Ikegami A, Nishimura Y, Tsuboi M. Increased stability of the higher order structure of chicken erythrocyte chromatin: nanosecond anisotropy studies of intercalated ethidium. Biochemistry 1985; 24:1291-7. [PMID: 3986177 DOI: 10.1021/bi00327a004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Internal motion of the DNA in chicken erythrocyte chromatin fibers was studied by measurement of the fluorescence anisotropy decay of ethidium intercalated in the linker region. A comparison of the decay curves of the dye in chicken erythrocyte chromatin with those of calf thymus chromatin [Ashikawa, I., Kinosita, K., Jr., Ikegami, A., Nishimura, Y., Tsuboi, M., Watanabe, K., Iso, K., & Nakano, T. (1983) Biochemistry 22, 6018-6026] revealed greater suppression of nucleosome movement in chicken erythrocyte chromatin. Furthermore, the transition of this chromatin to the compact (solenoidal) structure occurred at lower solvent concentrations of Na+ or Mg2+ than those for calf thymus chromatin. These results demonstrated increased stability of the higher order structure (the solenoid) of chicken erythrocyte chromatin, which may be related to the reduction of nuclear activity in the chicken erythrocyte cell. In addition to intact chicken erythrocyte chromatin, we studied the structural transitions of H1-depleted and H1,H5-depleted chromatins. The result indicated that histone H5 of this chromatin stabilizes the higher order structure in the presence of magnesium (or divalent) cation and did not induce the transition in the solution containing only sodium cation.
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13
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Mithieux G, Roux B, Marion C. Structural properties of barley nucleosomes. Biophys Chem 1984; 20:111-9. [PMID: 17005150 DOI: 10.1016/0301-4622(84)80011-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/1984] [Revised: 03/01/1984] [Accepted: 03/02/1984] [Indexed: 10/17/2022]
Abstract
The structural properties of barley oligonucleosomes are investigated and compared to those of rat liver oligomers. Extraction of barley chromatin was performed using mild nuclease digestion of isolated nuclei leading to a low ionic strength soluble fraction. Oligonucleosomes were fractionated on sucrose gradients and characterized for DNA and histone content. Physico-chemical studies (sedimentation, circular dichroism and electric birefringence) showed that barley oligonucleosomes exhibit properties very close to those of the H1-depleted rat liver counterparts. Moreover, in situ, barley linker DNA was more sensitive to micrococcal nuclease digestion than that of rat liver. These results suggest that barley oligonucleosomes show a less compact structure than their rat liver counterparts and appear to be in contradiction with the very condensed organization of barley chromatin previously suggested.
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Affiliation(s)
- G Mithieux
- Laboratoire de Physico-Chimie Biologique, Université Claudc Bernard - Lyon I, 69622 Villeurbanne Cedex, France
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14
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Krueger RC. The effect of low ionic strength on the circular dichroic spectrum of chromatin and nucleosomal subunits. Arch Biochem Biophys 1984; 231:183-8. [PMID: 6721497 DOI: 10.1016/0003-9861(84)90376-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Circular dichroism has been used to measure the conformation changes in the DNA of chromatin and chromatin subunits as a function of ionic strength. Transfer of chromatin from 0.15 M to 0.25 mM salt led to an enhancement of the circular dichroic bands at 275 and 285 nm. Removal of histone H1 did not appreciably affect the circular dichroic spectrum when measured in 0.15 M salt, but in 0.25 mM salt H1 depletion led to a marked increase in the ellipticity. Conformation changes due to low ionic strength were also observed with a 145- and a 172-bp chromatin subunit. A linear combination of the ellipticities of the DNA of the two domains in chromatin, namely core and linker, was successful for measurements at 0.15 M salt, but large unexplained discrepancies appeared with the data from measurements in 0.25 mM salt.
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15
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Butler AP, Laughlin TJ, Cadilla CL, Henry JM, Olins DE. Physical structure of gene-sized chromatin from the protozoan Oxytricha. Nucleic Acids Res 1984; 12:3201-17. [PMID: 6718249 PMCID: PMC318739 DOI: 10.1093/nar/12.7.3201] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Oxytricha nova is a hypotrichous ciliate containing a transcriptionally active macronucleus and a transcriptionally inactive micronucleus. Two-dimensional gel electrophoresis shows that macronuclei contain a normal complement of inner histones. However, despite extensive efforts, no classical H1-like protein has been detected. Micrococcal nuclease digestion indicates a nucleosome repeat length of approximately 220 bp for macronuclear chromatin. Thermal denaturation profiles of macronuclear chromatin in 0.2 mM EDTA display four transitions at about 46, 57, 64, and 79 degrees C. The lowest of these shifts to higher temperature as the ionic strength is raised to 3-5 mM Na phosphate. These results are consistent with the absence of H1 and a nucleosome repeat of 220-230 bp. Circular dichroism (CD) results agree with these findings. By contrast, micronuclear chromatin displays a much smaller premelt and a more suppressed DNA CD signal at 285 nm, consistent with a micronuclear chromatin repeat of 165-185 bp as determined by micrococcal nuclease digestion.
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16
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Abstract
The structure of chromatin in the presence of Mg2+ ions was examined by circular dichroism and equilibrium dialysis. Circular dichroism (CD) shows that above 260 nm the intensity of the spectrum of DNA in nucleoproteins decreases as the Mg2+ concentration increases. This change is an intrinsic characteristic of DNA since it is also observed in protein-free DNA and has been attributed to a change in the winding angle of base pairs around the DNA axis. Some structural elements of the DNA in the nucleosome core, therefore, are as movable as those of protein-free DNA. The basic organization of H1-depleted chromatin, 146 base pairs (bp) of DNA wound around core histones and a residual 49 bp in the linker region in the repeating unit, is maintained both in the presence and in the absence of Mg2+ ions, as shown by the fact that the CD spectrum of H1-depleted chromatin has the same type of linear combination between the spectrum of protein-free DNA and that of the nucleosome core in 0.2 mM MgCl2-10 mM triethanolamine (pH 7.8) as it has in 1 mM ethylenediaminetetraacetic acid-10 mM tris(hydroxymethyl) aminomethane (pH 7.8). The ellipticity of chromatin shows a smaller decrease relative to the other nucleoproteins and protein-free DNA upon the addition of Mg2+ ions. Therefore, some structural elements of chromatin are apparently somewhat protected against the conformational change induced by these ions. The spectrum of chromatin becomes almost indistinguishable from that of H1-depleted chromatin in 0.2 mM MgCl2.(ABSTRACT TRUNCATED AT 250 WORDS)
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Abstract
In order to study the chromatin structure of a higher plant we used a high-yield method, which allows one to obtain up to 10(9) nuclei/kg fresh barley leaves. Significant amounts of low-ionic-strength-soluble chromatin can be extracted from these nuclei. Physicochemical properties were examined and discussed. Electric birefringence allowed us to observe the same transition in electro-optical properties as has been observed for animal chromatin, and suggested the existence of a symetrical structure occurring for approximately six nucleosomes. Circular dichroism showed that barley oligonucleosomes exhibit a higher molar ellipticity at 282 nm than total soluble chromatin and than their animal counterparts.
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18
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Guerrero I, Alonso C. Fractionation by micrococcal nuclease digestion of Drosophila embryo chromatin: isolation of a fraction enriched in two major nonhistone proteins. CELL DIFFERENTIATION 1983; 12:307-16. [PMID: 6223703 DOI: 10.1016/0045-6039(83)90009-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Limited digestion of Drosophila melanogaster embryo nuclei with mitochondrial nuclease, followed by selective solubilization in 0.1 M NaCl, yields a soluble nucleoprotein fraction (S3) enriched in two dominant protein bands of apparent molecular weight of 44000 and 48000. The analysis of the nucleosome monomer and multimer peaks, separated on sucrose gradients after slight digestion with micrococcal nuclease, shows that these proteins are associated with chromatin subunits, and that they are principally found in the subnucleosome region of fraction S3. This doublet is tentatively identified as a member of the noncanonical HMG of Drosophila. The thermal denaturation and the circular dichroism spectra of the fraction soluble in 0.1 M NaCl (S3) and insoluble fraction (P3) show that both fractions are also structurally different.
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Grigoryev SA, Krasheninnikov IA. Transient unfolding of trypsin-digested chromatin core particles. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 129:119-25. [PMID: 7160375 DOI: 10.1111/j.1432-1033.1982.tb07029.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Limited digestion of nucleosome core particles with trypsin caused cleavage and removal of N-terminal histone sequences of 10-30 amino acids. The proteolyzed core particles exhibited salt-dependent structural transitions revealed by sedimentation, circular dichroism and nuclease-cutting assays, while the intact nucleosome cores were not affected under the experimental conditions. The results obtained indicate that the observed transitions correspond to the transient unfolding of terminal segments of core particle nucleoprotein caused by the increase of its net negative charge. The excision of the N-terminal histone domains therefore leads to partial destabilization but not to irreversible disruption of the compact nucleosome structure.
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Boulanger P, Loucheux-Lefevbre MH. Structure of adenovirus nucleoprotein core studied by circular dichroism and selective radiochemical labeling. Biochem Biophys Res Commun 1982; 107:470-80. [PMID: 6812580 DOI: 10.1016/0006-291x(82)91515-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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21
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McGhee JD, Felsenfeld G. Reconstitution of nucleosome core particles containing glucosylated DNA. J Mol Biol 1982; 158:685-98. [PMID: 7120415 DOI: 10.1016/0022-2836(82)90254-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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