Beta-Adrenergic Stimulation of CAV1.2 Channels is Transduced via the IS6-Aid Linker

Abstract

in approximately 1.7 superhelical turns. How this nucleosome-decorated DNA further folds into higher level arrangements has been a subject of intensive study since the discovery of the nucleosome. Models used to account for different experimental properties of chromatin often disagree with one another. We have recently found that these discrepancies may arise from the choice of nucleosome core particle (NCP) structure used in the model. Here we present a survey of the precise DNA folding around the histone core in all high-resolution nucleosome structures currently available in the Protein Data Bank. The subtle differences seen among the different NCP structures lead to significant changes in simulated chromatin fibers. For example, the slight changes in DNA folding between certain models have the same effect on chromatin structure as changing the nucleosome spacing by 2-3 base pairs. Structural changes of this nature alter the patterns of nucleosome association and convert the simulated chromatin structures between compact and extended forms. Consideration of the different nucleosomal DNA pathways takes account of the sedimentation coefficients extracted from ultracentrifugation studies, as well as the long-range communication between regulatory proteins studied under physiological conditions, providing a simple mechanism for modulating DNA accessibility.