The dissociation of nuclear proteins from superhelical DNA

Levin, Jeremy; Jost, Erich; Cook, Peter R.

doi:10.1242/jcs.29.1.103

Cited by 16 publications

(2 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It could also reflect steric strain imposed by the coiled DNA on the H2A-H2B complex. The latter factor would imply a role of H2A and H2B in coiling DNA as suggested by Levin et al (1978) and Kievan et al (1978).…”

Section: Unfolding Of Nuclei By Ureamentioning

confidence: 87%

On the mechanism of nucleosome unfolding

Martinson¹,

True²

1979

Biochemistry

View full text Add to dashboard Cite

We have studied the relative stabilities to urea denaturation of histone-histone binding interactions as they occur both in chromatin and in histone complexes free in solution. We have used the two zero-length contact-site cross-linking agents, tetranitromethane and UV light, to measure the relative degree of H2B-H4 and H2A-H2B association under various conditions. The two interactions were disrupted coordinately when nuclei were treated with increasing concentrations of urea. In contrast, when histone complex in 2 M NaCl were treated with urea, the H2B-H4 interaction was found to be much less stable than the H2A-H2B interaction. We have shown previously that nucleosomes unfold at low ionic strengths such that the H2B-H4 but not the H2A-H2B interaction is broken in the process. We speculate that the preferential rupture of the H2B-H4 contact is of physiological significance.

show abstract

Section: Unfolding Of Nuclei By Ureamentioning

confidence: 87%

On the mechanism of nucleosome unfolding

Martinson¹,

True²

1979

Biochemistry

View full text Add to dashboard Cite

show abstract

“…Nucleoids are DNA-containing and nuclear protein containing structures isolated by the lysis of cells at neutral pH with nonionic detergents and sedimentation in neutral, 1.9 M salt-sucrose gradients (Cook & Brazell, 1975). Histones and most other nonhistone nucleoproteins remain near the top of the gradients while some structural proteins sediment with the DNA (Cook & Brazell, 1975, 1976Levin et al, 1978;Lebkowski & Laemmli, 1982). Removal of nucleosomes accounts for the negative supercoiling of nucleoids (Cook & Brazell, 1975, 1976.…”

mentioning

confidence: 99%

Absence of swiveling at sites of intercalator-induced protein-associated deoxyribonucleic acid strand breaks in mammalian cell nucleoids

et al. 1984

View full text Add to dashboard Cite

The sedimentation of DNA-nuclear protein complexes in 1.9 M salt-neutral sucrose gradients (nucleoid sedimentation) was used to examine the effects of the DNA intercalator 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) on mouse leukemia cell DNA. Mild detergent cell lysis and neutral pH make nucleoid sedimentation an extremely gentle, but sensitive, method to detect DNA scission. DNA breaks reduce the compaction of nucleoids and slow their sedimentation. Nucleoids from m-AMSA-treated cells sedimented as did those from untreated cells, indicating no detectable m-AMSA-dependent alterations in compaction despite an apparent underlying DNA break frequency of approximately 3 per 10(6) nucleotides, as measured by alkaline elution with proteinase. Mild proteinase digestion of cell lysates prior to nucleoid sedimentation unmasked some, but not all, of the underlying breaks. The frequency of DNA-protein cross-links in nucleoids from cells treated with m-AMSA was comparable to the single-strand break frequency produced by m-AMSA in whole cells. These results indicate that m-AMSA-induced DNA-protein cross-links conceal DNA breaks so as to prevent swiveling around the breaks within the nucleoids. This unique sort of DNA scission is consistent with the involvement of topoisomerases in the DNA breaks elicited by intercalators in mammalian cells.

show abstract

Conformational transitions in closed circular DNA molecules II. Biological implications

Luchnik

1980

Mol Biol Rep

View full text Add to dashboard Cite

A model of regulation of gene action based on the theory of conformational transitions in closed circular DNA molecules is proposed and discussed in connection with the mechanisms of cellular differentiation. The model predicts two main types of regulation of gene action (1) the change in the topological linking number of the DNA loops leading to the change in the amount of the DNA segments present in the transcriptionally active A-form and (2) the change of some nucleotide sequences in closed superhelical DNA loops resulting in conformational transitions of some of the other sequences in the same loop. The first type of regulation may explain the mechanism of terminal differentiation of the stem cells and the changes accompanying the malignant transformation. The second one may explain the variegated position effect of the gene and determination of the stem cells during ontogenesis.

show abstract

The dissociation of nuclear proteins from superhelical DNA

Cited by 16 publications

References 35 publications

On the mechanism of nucleosome unfolding

On the mechanism of nucleosome unfolding

Absence of swiveling at sites of intercalator-induced protein-associated deoxyribonucleic acid strand breaks in mammalian cell nucleoids

Conformational transitions in closed circular DNA molecules II. Biological implications

Contact Info

Product

Resources

About