Industrial and Pharmaceutical Microbiology

Biography

Biography: Gyanendra Singh

Abstract

Epstein-Barr virus (EBV) infects around 95% of human population and its causal association with B-cell lymphomas in children from Sub-Saharan African countries has been established by various epidemiological and molecular studies. Epstein-Barr nuclear antigen 1 (EBNA1), an EBV protein is required for immortalization and transformation of B-cells and results in wide spectrum of diseases that range from infectious mononucleosis to malignancies such as Hodgkin's lymphoma, non-Hodgkin's lymphoma, AIDS related immunoblastic lymphomas, gastric carcinoma, post-transplant lymphomas etc. It is known that transcription activation requires a domain of EBNA1 that binds AT-rich DNA and a second domain termed unique region 1 (UR1) that is conserved in the EBNA1 orthologs of other EBV-like gammaherpesviruses. We have shown in earlier studies that EBNA1's ability to activate transcription is zinc dependent and the two conserved cysteines within UR1 domain are absolutely required for zinc coordination and also respond to the change in the redox microenvironment. We have used bimolecular fluorescence complementation and co-immunoprecipitation techniques to demonstrate that zinc is essential for EBNA1 to transactivate. In addition to zinc regulation, the two critical cysteines within conserved UR1 region are also subject to redox regulation. Oxidative stress conditions are known to cause cysteine oxidation and results in reduced EBNA1's ability to transactivate. We wanted to know whether by over expression of redox proteins such as apurinic/apyrimidinic endonuclease redox effector factor-1 (APE1/Ref-1) modulates EBNA1's ability to transactivate and counteracts the effect of oxidative stress on EBNA1. Our results identify a novel mechanism by which redox regulators modulates EBNA1's ability to transactivate and counteracts the effect of oxidative stress on EBNA1.