The helicase/SUMO-targeted ubiquitin ligase Uls1 interacts both physically and functionally with the Holliday junction resolvase Yen1
(English)Manuscript (preprint) (Other academic)
Yen1 is nuclease that can cleave the Holliday junction (HJ), an important DNA intermediate formed during homologous recombination. Here, we show that Yen1 interacts molecularly with Uls1, a SUMO targeted ubiquitin ligase that also belongs to the SWI/SNF-family of DNA-dependent ATPases. We demonstrate that Yen1 is SUMO modified in its carboxyl terminus and that this modification strengthens the interaction between Yen1 and Uls1. Absence of Uls1 increased the steady-state levels of Yen1, but only after extensive DNA damage, suggesting that Uls1 has a role in damage-induced degradation of Yen1. Consistent with a shared role for Uls1 and Yen1, mutations in the two enzymes display similar phenotypes. Both uls1 and yen1 have a negative genetic interaction with the alternative HJ-cleaving nuclease Mus81. This negative genetic interaction is manifested in supersensitivity to DNA damaging agents, but also in a meiotic defect. Neither mus81 uls1 nor mus81 yen1 double mutant diploids can complete meiosis. Moreover, both uls1 and yen1 exacerbates the chromosome mis-segregation phenotype of mus81. However, the mus81 uls1 yen1 triple mutant strain was slightly more sensitive to DNA damage compared to any double mutant combination, indicating that Uls1 and Yen1 also have independent roles in DNA repair. Point mutant alleles of Uls1 (uls1K975R and uls1C1330S/C1333S) that inactivates the ATPase and potential ubiquitin ligase activities are also supersensitive to DNA damage when combined with mus81, indicating that both activities of Uls1 are essential for function. We suggest that Yen1 and Uls1 are involved in an alternative pathway that is responsible for resolving complex DNA repair intermediates in the absence of Mus81.
Research subject Developmental Biology
IdentifiersURN: urn:nbn:se:su:diva-81361OAI: oai:DiVA.org:su-81361DiVA: diva2:561116