Pulling a single chromatin fiber reveals the forces that maintain its higher-order structure
AUTOR(ES)
Cui, Yujia
FONTE
The National Academy of Sciences
RESUMO
Single chicken erythrocyte chromatin fibers were stretched and released at room temperature with force-measuring laser tweezers. In low ionic strength, the stretch-release curves reveal a process of continuous deformation with little or no internucleosomal attraction. A persistence length of 30 nm and a stretch modulus of ≈5 pN is determined for the fibers. At forces of 20 pN and higher, the fibers are modified irreversibly, probably through the mechanical removal of the histone cores from native chromatin. In 40–150 mM NaCl, a distinctive condensation-decondensation transition appears between 5 and 6 pN, corresponding to an internucleosomal attraction energy of ≈2.0 kcal/mol per nucleosome. Thus, in physiological ionic strength the fibers possess a dynamic structure in which the fiber locally interconverting between “open” and “closed” states because of thermal fluctuations.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=26627Documentos Relacionados
- Higher-order structure of Saccharomyces cerevisiae chromatin.
- Higher-order structure of long repeat chromatin.
- Distinctive higher-order chromatin structure at mammalian centromeres
- Higher-order structure of nucleosome oligomers from short-repeat chromatin.
- Higher-order structure of human mitotic chromosomes.