Involvement of histone H1 in the organization of the nucleosome and of the salt-dependent superstructures of chromatin.

Thoma, Fritz; Koller, Th.; Klug, A.

doi:10.1083/jcb.83.2.403

Cited by 1,500 publications

(1,072 citation statements)

References 55 publications

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“…However, the X‐ray diffraction data of Widom and Klug 12 supporting a low‐pitch structure was obtained using hexamminecobalt as one of the condensing cations. In general such multivalent cations are more effective condensing agents than the sodium ion used in the initial studies of chromatin condensation [30, 31, 32, 33; see also 34] and would be expected to reduce the pitch angle of the chromatin fibre by favouring the closer approach of the two nucleosome stacks.…”

Section: Relation To Previous Workmentioning

confidence: 99%

A metastable structure for the compact 30‐nm chromatin fibre

McGeehan

Travers

2016

FEBS Letters

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The structure of compact 30‐nm chromatin fibres is still debated. We present here a novel unified model that reconciles all experimental observations into a single framework. We propose that compact fibres are formed by the interdigitation of the two nucleosome stacks in a 2‐start crossed‐linker structure to form a single stack. This process requires that the dyad orientation of successive nucleosomes relative to the helical axis alternates. The model predicts that, as observed experimentally, the fibre‐packing density should increase in a stepwise manner with increasing linker length. This model structure can also incorporate linker DNA of varying lengths.

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Section: Relation To Previous Workmentioning

confidence: 99%

A metastable structure for the compact 30‐nm chromatin fibre

McGeehan

Travers

2016

FEBS Letters

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“…Whether the helical form of the 30-nm fiber is a 1-start helix or solenoid (Finch and Klug 1976;Thoma et al 1979;Felsenfeld and McGhee 1986) with a single stack of nucleosomes, a 2-start helix with two continuous stacks (Williams et al 1986;Bordas et al 1986a, b;Woodcock et al 1984;Worcel et al 1981) analogous to DNA, or a multi-start helix (Daban and Bermúdez 1998), or whether fibers with different NRLs differ in topology (Wong et al 2007) has been extensively debated. There is now compelling experimental evidence that the '30-nm' fiber can adopt a 2-start structure.…”

Section: -Nm Fibermentioning

confidence: 99%

The regulatory role of DNA supercoiling in nucleoprotein complex assembly and genetic activity

Muskhelishvili

Travers

2016

Biophys Rev

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We argue that dynamic changes in DNA supercoiling in vivo determine both how DNA is packaged and how it is accessed for transcription and for other manipulations such as recombination. In both bacteria and eukaryotes, the principal generators of DNA superhelicity are DNA translocases, supplemented in bacteria by DNA gyrase. By generating gradients of superhelicity upstream and downstream of their site of activity, translocases enable the differential binding of proteins which preferentially interact with respectively more untwisted or more writhed DNA. Such preferences enable, in principle, the sequential binding of different classes of protein and so constitute an essential driver of chromatin organization.Keywords DNA supercoiling . DNA translocases . Chromatin organization . Superhelicity gradients . DNA untwisting . DNAwrithing Dynamic changes of DNA supercoiling act as a driving force behind the alterations of genetic activity and DNA compaction both in eukaryotes and prokaryotes. Both these processes involve formation of spatially organized nucleoprotein structures by DNA architectural proteins. Whereas in eukaryotes the paradigmal example is the histone octamer, in prokaryotes a similar function is attributed to a small class of highly abundant nucleoid-associated proteins. We argue that, depending on the primary sequence organization, the changes of superhelicity elicit various alterations of local DNA geometry, while these, in turn, facilitate the assembly of distinct nucleoprotein structures pertinent to genetic function. Genome-wide conversion of the superhelical energy into various three-dimensional DNA structures thus acts as an analogue code coordinating the energy supply with the genetic expression of the chromosome.Recent studies make it increasingly clear that the DNA double helix carries at least two types of encoded information and that these include the well-known genetic code and the structural information determining the form and physical properties of the double helix itself. Since both these information types are inscribed in the same DNA sequence, and yet one is discrete whereas the other is continuous, they have been respectively dubbed the digital and analog DNA codes (Marr et al. 2008;Travers et al. 2012;Muskhelishvili and Travers 2013). The potential of the DNA to adopt distinct configurations is strongly modulated by DNA supercoiling, which is increasingly recognized as one of the major forces coordinating the cellular DNA transactions in both prokaryotes (including Archaea) and eukaryotes.DNA supercoiling can be generated by the simple application of torque to the double helix (Strick et al. 1998) but, importantly, because the DNA molecule itself possesses chirality-it is, after all, a right-handed double helix-the local structures stabilized by changes in superhelical density depend on both the sign and strength of the applied torque. For example, both positive and negative torque (respectively overand underwinding of the double helix) can change the intrinsic coiling of ...

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“…Approximately 10 g liver from rats was homogenized in the presence of 1 mM phenylmethylsulphonylfluoride (PMSF) and the nuclei were purified by centrifugation through sucrose cushions (Thoma, Roller & Klug, 1979;Hecker & Gander, 1985). T. b. brucei STIB 345 AB were harvested, and 2-3 x 10 10 exponentially growing procyclic cells resuspended in hypotonic buffer containing 0-5 M 2-methyl-2,4-pentandiol (hexylene glycol), 2-5 mM CaCl 2 , 1 mM PMSF.…”

Section: Purification Of Nucleimentioning

confidence: 99%

Trypanosoma brucei brucei: differences in the nuclear chromatin of bloodstream forms and procyclic culture forms

et al. 1993

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SUMMARYNucleosome filaments of two stages of the life-cycle of Trypanosoma brucei brucei, namely bloodstream forms and procyclic culture forms, were investigated by electron microscopy. Chromatin of bloodstream forms showed a salt-dependent condensation. The level of condensation was higher than that shown by chromatin from procyclic culture forms, but 30 nm fibres as formed in rat liver chromatin preparations were not found. Analysis of histones provided new evidence for the existence of HI-like proteins, which comigrated in the region of the core histones in SDS-PAGE and in front of the core histones in Triton acid urea gels. Differences were found between the HI-like proteins of the two trypanosome stages as well as between the core histones in their amount, number of bands and banding pattern. It can be concluded that T. b. brucei contains a full set of histones, including HI-like proteins, and that the poor condensation of its chromatin is not due to the absence of H1, but most probably due to histone-DNA interaction being weak. It is obvious that structural and functional differences of the chromatin exist not only between T. b. brucei and higher eukaryotes, but also between various stages of the life-cycle of the parasite. It is therefore not adequate to investigate the chromatin only of the procyclic culture forms as a model for all stages of the life-cycle of T. b. brucei.

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Involvement of histone H1 in the organization of the nucleosome and of the salt-dependent superstructures of chromatin.

Cited by 1,500 publications

References 55 publications

A metastable structure for the compact 30‐nm chromatin fibre

A metastable structure for the compact 30‐nm chromatin fibre

The regulatory role of DNA supercoiling in nucleoprotein complex assembly and genetic activity

Trypanosoma brucei brucei: differences in the nuclear chromatin of bloodstream forms and procyclic culture forms

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