Interview with Thiago Rodrigo dos Santos, Molecular Microbiology Poster Award winner at 2nd Workshop in Microbial Molecular Biology in Campinas, Brazil.

Abstract

Molecular Microbiology Poster Award—Thiago Rodrigo dos Santos, master's student at the University of São Paulo for their poster entitled ‘Characterization of an antibacterial Type IV Secretion System effector/inhibitor pair with nuclease activity in Xanthomonas citri’. My name is Thiago Rodrigo dos Santos. I have an undergraduate degree in biochemical engineering from the University of São Paulo (USP). And, I am a final year master's student at the Institute of Chemistry. Bacteria sharing the same niche must compete for nutrients and space. In this project, our goal was to understand the bactericidal type IV secretion system of Xanthomonas citri, an important phytopathogen that causes large damage to citrus crops. The type IV secretion system, which is part of a new family of type IV secretion systems, can transport several types of bactericidal proteins to the periplasm of other bacteria. I work under the supervision of Professor Shaker Chuck Farah, who is a pioneer in the study of this system. In this project, I worked with a putative effector-inhibitor pair of the type IV secretion system. Computational analyses predicted that this effector had nuclease activity, leading us to hypothesize that this effector acts as a toxin that degrades the target cell's DNA. We showed, by using heterologous expression, that the effector protein is toxic on microbial growth. Bacterial competition assays further showed that the effector confers a strong competitive advantage. Using a reporter strain, we then showed that the effector activates the E. coli DNA repair response, and that this protein can degrade plasmids in in vivo assays. We finally showed that the putative related inhibitor can suppress the activity of the effector, confirming that the proteins form an effector-inhibitor pair. After finishing my master's degree, I intend to continue developing studies with bacterial effectors. To this end, I intend to enroll in a doctoral program in biochemistry and molecular biology of microorganisms, probably in another research center, as this would allow me to have a greater variety of academic experiences. Thiago Rodrigo dos Santos, Institute of Chemistry, University of São Paulo. E-mail: [email protected]