Hyperacetylated histones facilitate chromatin assembly in vitro (original) (raw)
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Modulation of the Nucleosome Structure by Histone Acetylation
European Journal of Biochemistry, 1980
A rapid procedure for the isolation of core particles from Chinese hamster ovary cells is described which permits measurements, usually at the day of their preparation. Particles of 145 f 5 base pairs, derived from interphase cells, will be compared with the analogue specimens from butyrate-treated cells, metaphase cells and a standard preparation from chicken erythrocytes. Butyrate cause an increase in the acetylation of histones H3 and H4, which induces alterations of the interhistone and histone-DNA interactions. Changes in the interhistone contacts, correlated to an extension of a-helical segments, lead to an altered accessibility of the H3 cysteine side-chains and to a different histone displacement by protamines. On the other hand, histone-DNA contacts are loosened in parts and this is particularly evident from the changes in the premelting region of a thermaldenaturation profile.
Histone H1 deposition and histone-DNA interactions in replicating chromatin
Proceedings of the National Academy of Sciences, 1993
An immunochemical method for analyzing protein interactions with BrdUrd-substituted DNA was used to study binding of histones to nascent DNA in nuclei. The results indicate that in Ehrlich ascites tumor (EAT) cells, histone Hi deposits on newly replicated DNA simultaneously with or immediately after core histone deposition so that in chromatin replicated for 3 min, the stoichiometry of the histones is the same as in bulk chromatin. All histones, and especially histone Hi, interact with nascent DNA more weakly than with bulk
Assembly of new histones into nucleosomes and their distribution in replicating chromatin
Proceedings of the National Academy of Sciences, 1982
We studied the assembly of new histones into nucleosomes and their distribution in replicating chromatin in growing P815 mouse cells. New histones and new DNA were density-labeled with '3C,'5N,2H-substituted amino acids together with [3H]arginine or with 5-iododeoxyuridine and [3H]thymidine, respectively, for 1 hr (=20O% of S phase). Mono-, di-, tri-, tetraand larger oligonucleosomes were isolated by sucrose gradient centrifugation of micrococcal nuclease-digested chromatin, and their density distribution was analyzed, without fixation, in metrizamide/triethanolamine density gradients Nucleic Acids Res. 3, 697-707] in which monoand oligonucleosomes containing dense amino acids or 5-iododeoxyuridine separate from the corresponding normal nucleosomes. Under these conditions, 474% of the new histones are found in nucleosomes on newly replicated DNA, and the remainder are on unreplicated DNA. The majority of new histones form entirely new nucleosomes; a minor fraction may form hybrid nucleosomes that also contain preexisting histones. New nucleosomes are distributed to both new daughter DNA molecules with approximately equal probability, and our evidence suggests, but does not prove, that they are distributed in a random manner along new DNA.
European Journal of Biochemistry, 2005
Poly(ADP-ribose) [poly(ADP-Rib)] polymerase of HeLa nucleosomes has been shown in vitro, to catalyze the synthesis of a complex of histone H1 containing 2 H1 histones and 15-16 units of oligo(ADP-Rib). The synthesis of the H1 complex in vitro was compared in polynucleosome populations of various sizes (3-16 and > 30) released from HeLa nuclei following micrococcal nuclease digestion. Poly(ADP-Rib) was synthesized from [32P]NAD and the poly(ADP-ribosy1)ation of H1 was studied by selective H1 extraction, gel electrophoresis and autoradiography. Quantitative differences in H1 complex formation occurred when either chromatin concentration or polynucleosome length was varied. The data indicated that H1 complex formation in vitro was favored in polynucleosomes 16 nucleosomes long as compared to 8 nucleosomes. A series of partially ADP-ribosylated H1 species was also detected. Partially modified H1 species migrate more slowly than pure H1 in dodecylsulfate gels. The reduced mobility is a function of the number of attached ADP-Rib moieties. Thus, molecules containing one molecule of HI and various numbers of ADP-Rib residues can be separated. When the partially modified H1 species were incubated in alkali to cleave the linkage of ADP-Rib to protein, (ADP-Ribl-15) were detected by chain length analysis on 15% polyacrylamide gels. The intermediate H1 species could be chased, in vitro, into as H1 complex with NAD and thus were determined to be successive precursors in the formation of the H1 complex. Evidence is presented that the H1 complex is synthesized in intact cells permeabilized with lysolecithin. A chromatin-associated enzyme, poly(ADP-Rib) polymerase, catalyzes the successive transfer of the ADP-Rib moiety of NAD to various nuclear protein acceptors, including histone H1, core histone H2A, H2B and H3 and other non-histones. Several reviews have recently appeared on this enzyme system [1,2]. Transient modification of the core histones by acetylases and protein kinases appears to play a role in the assembly of nucleosome cores during replication and transcription [3,4], and it is likely that modification of other chromatin structural proteins plays an important role in the organization of higher-ordered folding during DNA synthesis and/or other functional periods of the cell cycle. Histone H1 has been implicated in condensation of the spacer regions of DNA between core particles [5] and in stabilizing higher-Abbreviations. ADP-Rib, adenosine diphosphate ribose; PhMeS02F, phenylmethylsulfonyl fluoride.