Budding yeast Wpl1p regulates cohesin functions in cohesion, condensation and DNA repair by a common mechanism

Cohesin tethers DNA to mediate sister chromatid cohesion, chromosome condensation, and DNA repair. How the cell regulates cohesin to perform these distinct functions remains to be elucidated. One cohesin regulator, Wpl1p, was characterized in the budding yeast, Saccharomyces cerevisiae, as a promoter of cohesion and as an inhibitor of condensation. Here we provide evidence that Wpl1p has an additional function in promoting the timely repair of DNA damage induced during S-phase. In addition to these biological functions, Wpl1p has been implicated as an inhibitor of cohesin9s ability to stably bind DNA by modulating the interface between two subunits (Mcd1p and Smc3p) of the core cohesin complex. We show that Wpl1p likely modulates this interface to regulate all cohesin9s biological functions. Furthermore, we show that Wpl1p regulates cohesion and condensation through the formation of a functional complex with another cohesin-associated factor, Pds5p. In contrast, Wpl1p regulates DNA repair independently of its interaction with Pds5p. Together these results suggest that Wpl1p regulates distinct biological functions of cohesin by Pds5p-dependent and independent modulation of the Smc3p-Mcd1p interface.