Caratterizzazione biochimica e funzionale del complesso 9-1-1 in S. cerevisiae, crocevia tra checkpoint e sistemi di tolleranza al danno

The DNA damage checkpoint is a series of complex mechanisms that monitor cell cycle progression in response to genotoxic insults. Once activated it leads to a cell cycle slowdown and the instauration of a complex protein network involving physical and functional interaction with various DNA metabolism reactions (replication, repair, recombination). Moreover a series of tolerance systems have been developed in case the damage would arrive to S phase. One of those systems is the DNA translesion synthesis that using specialized DNApolymerases is able to replicate over the lesion allowing replication fork progression. Using a variety of different genetic and biochemical approaches such as yeast 2-hybrid, coimmunoprecipitations, in vitro pulldown and coimmunolocalization we characterized the complex formed by the Ddc1, Rad17 and Mec3 proteins (also called 9-1-1 complex) and we were able to detect a possible interaction between the 9-1-1, involved in the first step of the checkpoint signaling cascade, and Rev7 a regulatory subunit of PolZ one of the most important translesion polymerase in yeast. Altogether these interactions strongly support an internal crosstalk between different repair system and cell cycle control.