Chromatin fiber polymorphism triggered by variations of DNA linker lengths

Significance The structure of the chromatin fiber remains one of the most fundamental open biological questions because structure dictates many template-directed processes. We use coarse-grained modeling to investigate systematically how variations in the linker DNA length that arise naturally for chromatin in different tissues, species, and cell cycle stages affect fiber architecture. We unravel a natural source of fiber polymorphism, in which irregular interdigitated 10-nm and compact 30-nm fibers coexist. These results suggest how structural diversity can be advantageous for gene regulation activity. Interesting DNA design applications also arise.