Chromatin higher-order folding as influenced by preferred values of linker DNA

Specific values of nucleosome spacing have long been associated with distinct chromatin organization, but recent studies reveal surprising structural and functional consequences of small changes in regular linker DNA length. This opinion article revisits experimental and modeling studies addressing the classic 10n versus 10n + 5 spacing, highlighting how this 5 bp difference can alter nucleosome orientation, fiber topology, and higher-order chromatin behavior. We underscore how differences in model parameters and system design yield different trends for the effect of linker DNA lengths on chromatin architecture. However, chromatin structure in vivo reflects the heterogeneous nucleosome spacing in combination with other cellular variables like salt conditions, epigenetic marks, and protein and RNA binding, which work together to shape gene folding and direct gene regulation.