The zinc finger of DNA ligase 3α binds to nucleosomes via an arginine anchor.

ABSTRACT: Ligation of DNA single strand breaks is critical for maintaining genome integrity during DNA replication and repair. DNA Ligase III (LIG3α) forms an important complex with X-ray cross complementing protein 1 (XRCC1) during single strand break and base excision repair. We utilize a real time single molecule approach to quantify DNA binding kinetics of HaloTag-LIG3α and XRCC1-YFP from nuclear extracts on long DNA substrates containing nicks, nucleosomes or nicks embedded in nucleosomes. LIG3α displays higher affinity for nicks than XRCC1 with the LIG3α catalytic core and N-terminal zinc finger (ZnF) competing for nick engagement. Surprisingly, compared to single strand breaks in naked DNA, LIG3α binds even more avidly to an undamaged nucleosome reconstituted on the 601-sequence, with binding

SUBMITTER: Nagpal A 

PROVIDER: S-EPMC12748704 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature