eccDNA formation follows 10.5-bp periodicity tied to nucleosome minor-groove orientation
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A preprint posted on bioRxiv reports that extrachromosomal circular DNA (eccDNA) is not formed at random sites: its length and breakpoints reflect chromatin structure. Across 25 datasets spanning multiple species, tissues and experimental approaches, eccDNA length showed periodicities of about 180 bp and 10.5 bp, corresponding to nucleosome length and the DNA helical repeat. Breakpoint mapping showed breaks occur more often in linker DNA between nucleosomes, and within nucleosome-bound DNA they prefer positions where the minor groove faces the histone surface. The findings support a mechanism in which chromatin geometry helps determine where eccDNA forms. The work is a preprint and has not yet been peer reviewed, and the extent to which the periodicity generalises across tumour types and conditions remains open.
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- bioRxivExtrachromosomal 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
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