Principal Investigator: Dr Milorad Kojic

            This proposal is mainly about two pivotal cellular functions (genome integrity control and protein oxidative damage control) and it centrally concerns Dss1 protein. Elucidating the role of Dss1 in these processes is of fundamental scientific interest. Moreover, the knowledge will have important implications for understanding and possibly treatment of numerous human disorders and diseases.  In recent years the investigations of the Dss1 has largely been focused on its essential role in BRCA2-driven recombinational DNA repair. BRCA2 has emerged as the product of a breast cancer susceptibility gene in human and then came to be realized as a central component of the homologous recombination system. Although these studies clearly demonstrated the importance of the Dss1 protein for the number of BRCA2 functions, it remained mostly enigmatic how their interplay is coordinated with other cellular events to ensure the controlled maintenance of genetic integrity. Furthermore, the Dss1’s role in the detection and clearing of oxidatively damaged proteins was discovered fairly recently. This novel type of posttranslational protein modification (named as DSSylation) is conditionally induced by free radicals via an ATPase-mediated process. Like many other intriguing breakthrough study, this one too provided more questions than answers. Hence, this project seeks to shift emphasis from BRCA2-Dss1 interplay and to broaden our perspective of how homologous recombination is connected to other pivotal cellular events. The fundamental assumption is that Dss1 might well be the conduit that connects DNA repair to the protein oxidative damage control.  We plan to use the Ustilago maydis experimental system for this study because the facility it offers for performing rapid molecular genetic operations will provide a powerful means for attacking the problems. Specifically, we propose to: 1) perform an innovative screen to identify suppressors that could bypass cellular requirement for Dss1,  2) investigate the role of Dss1 in cellular response to oxidative insult,  3) identify new factors cooperating with Dss1 in its modifier activity, 4) identify the ATP-ase that catalyzes the binding of DSS1 to the oxidized proteins. The factors and processes studied in the project will significantly enhance our knowledge of the networks that govern cellular response to DNA damage and oxidative stress.  We therefore anticipate that our findings will greatly contribute towards further understanding of a number of human disorders (aging) and diseases (raging from inflammation to cancer). They should also help shape strategies for preventative diagnosis and therapy by providing insight into possible drug targets.