Phosphodiester bonds between polypeptides and chromosomal DNA

High salt- and SDS-stable DNA binding protein complexes with ATPase and protein kinase activity retained in chromatin-depleted nuclei

“…2b). Thus, at present, we have no experimental evidence for a potential relationship between the polypeptides co-isolating with DNA during the salting-out procedure and those bound to DNA by covalent nucleotide-peptide bonds previously detected in phenol-extracted DNA (4,5).…”

“…Previously we found that a small but persistent amount of nuclear polypeptides remains associated with eukaryotic DNA submitted to the most rigorous deproteinization methods, including treatment with SDS, proteinase K and phenol. The chemical stability of this DNA-peptide interaction is apparently based on covalent bonds between hydroxy amino acid residues:in polypeptides and internucleotide phosphates (4,5). Complexes of this type seem to reside preferentially on highly repetitive DNA sequences which have been cloned (6)(7)(8) and shown to be highly enriched in residual nuclear matrix DNA (9).…”

Highly sensitive sites for guanine-O6 ethylation in rat brain DNA exposed to N-ethyl-N-nitrosourea in vivo.

“…The overall alkylation level in rat mitochondrial DNA ex- posed to methylating N-nitroso compounds (N,N-dimethylnitrosamine, N-methyl-N-nitrosourea) exceeds that of rat nuclear DNA by a factor of s5 (Wunderlich et al, 1971;Wilkie and Evans, 1982 The fact that clustered O6-EtdGuo sites were only observed in DNA fragments contained in a fraction of DNA isolated by virtue of its association with specific polypeptides may be explained by two alternative hypotheses. (i) The tightly bound polypeptides found in chromosomal DNA (Bodnar et al, 1983;Krauth and Werner, 1979;Neuer et al, 1983;Werner et al, 1981a) may be involved in a nuclear structure and/or function which renders the vicinal DNA more accessible to the ethyldiazonium ions generated from EtNU (see, e.g., the putative mechanisms a -d mentioned above). (ii) It may be argued that by virtue of particular structural properties of its own, a small fraction of DNA might be more sensitive to ethylation by EtNU.…”

“…As previously shown, highly purified chromosomal DNA still contains distinct types of polypeptides (Bodnar et al, 1983;Krauth and Werner, 1979;Werner et al, 1981a) which are covalently bound to internal ends of DNA molecules (Neuer et al, 1983). DNA fragments containing such DNA-protein complexes may be essential constituents of higher order chromatin structures and/or be involved in the anchorage of DNA in nuclear structures (Bodnar et al, 1983;Werner et al, 1980Werner et al, , 1981a.…”

“…Using a high-affinity anti-(06-EtdGuo) monoclonal antibody (ER-6;Rajewsky et al, 1980;Adamkiewicz et al, 1982) (Bodnar et al, 1983;Spiess et al, 1982). The material specifically adsorbed to the filters was recovered and, in parallel with equal amounts of the material that had passed through the filters, was radiolabeled with 1251I exclusively on tyrosines (Neuer et al, 1983). Iodinated polypeptides from both types of material were then analyzed by SDS-PAGE and autoradiography.…”