Cooperativity in nucleosomes assembly on supercoiled pBR322 DNA.
AUTOR(ES)
Forte, P
RESUMO
Many studies have shown that in reconstituted chromatin model systems, containing only purified DNA and histone octamer, nucleosomes can adopt well defined locations with respect to DNA nucleotide sequence. Recently, nucleosome-nucleosome interactions were suggested as one of the factors underlying preferential nucleosomes positioning. In the present paper this aspect has been studied by topological analysis and electron microscopy visualization of minichromosomes reconstituted at different histone/DNA ratios. Both methods suggest that cooperativity plays a role in nucleosomes formation. A linear cooperative model in which nucleosomes are formed on discrete sites with cooperative interactions occurring only between nearest neighbours allows to calculate the cooperative constant. The reported results show that basic interactions, which are of relevance in the process of chromatin folding, are present also in very simple model system.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=335036Documentos Relacionados
- Ozonolysis of supercoiled pBR322 DNA resulting in strand scission to open circular DNA.
- Influence of DNA topology and histone tails in nucleosome organization on pBR322 DNA.
- Altered DNA conformations detected by mung bean nuclease occur in promoter and terminator regions of supercoiled pBR322 DNA.
- Deletion mutants defining the Escherichia coli replication factor Y effector site sequences in pBR322 DNA.
- Conservative integration of bacteriophage Mu DNA into pBR322 plasmid.
