Extrachromosomal circular DNA formation follows a 10.5-bp periodicity reflecting the minor groove orientation around nucleosomes

The authors systematically analysed 25 datasets spanning multiple species, tissues and experimental approaches, finding that eccDNA length shows periodicities of roughly 180 bp and 10.5 bp, corresponding to nucleosome length and the DNA helical repeat, respectively. Breakpoint mapping showed breakpoints occur more often in linker DNA between nucleosomes; within nucleosome-bound DNA, they favour positions where the minor groove faces the histone surface, supporting a role for chromatin geometry in eccDNA biogenesis. DOI: https://doi.org/10.64898/2026.10.19.760212