Biology subjects

Freeman, A. D. J.

Publications and source records attributed to Freeman, A. D. J..

2 recordsLinked to original sources

bioRxiv2025

The ultrafine-bridge-associated endonuclease ANKLE1 is stimulated by tension in DNA to process branch-points

Covalent linkages between chromosomes are naturally formed as a result of recombination or DNA replication. These can persist until late mitosis, resulting in interchromosomal ultrafine bridges, preventing cell division and causing genome instability. The endonuclease ANKLE1, localised at the cell midbody during cytokinesis and selective for DNA branchpoints, is ideally poised to act as an enzyme of last resort to process interchromosomal bridges, enabling cell division to proceed. However, how ANKLE1 cleaves DNA under the tension existing in interchromosomal bridges during mitosis remains unexplored. Using optical tweezers, we show that ANKLE1 is a tension-stimulated endonuclease. High tension in DNA increases the ANKLE1 junction cleavage rate, with a twenty-fold increase at 60 pN. This indicates that ANKLE1 has evolved to respond to tension-induced DNA structural changes, thereby facilitating nucleolytic activity. This novel mechano-enzymological response of ANKLE1 reveals how it is well-suited to process ultrafine-bridges during late mitosis.

biophysics↗

bioRxiv2020

Human ANKLE1 is a nuclease specific for branched DNA

ABSTRACTAll physical connections between sister chromatids must be broken before cells can divide, and eukaryotic cells have evolved multiple ways in which to process branchpoints connecting DNA molecules separated both spatially and temporally. A single DNA link between chromatids has the potential to disrupt cell cycle progression and genome integrity, so it is highly likely that cells require a nuclease that can process remaining unresolved and hemi-resolved DNA junctions and other branched species at the very late stages of mitosis. We argue that ANKLE1 probably serves this function in human cells (LEM-3 in C. elegans). LEM-3 has previously been shown to be located at the cell mid-body, and we show here that human ANKLE1 is a nuclease that cleaves a range of branched DNA species. It thus has the substrate selectivity consistent with an enzyme required to process a variety of unresolved and hemi-resolved branchpoints in DNA. Our results imply that ANKLE1 acts as a catch-all enzyme of last resort that allows faithful chromosome segregation and cell division to occur.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biochemistry↗