Molecular mechanisms of the Xanthomonas citri resistance to Dictyostelium discoideum predation and the role of the type VI secretion system

• Grant number: 22/06555-3
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2022
• End date: August 31, 2026
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Agreement: Swiss National Science Foundation (SNSF)
• Principal Investigator: Cristina Elisa Alvarez Martinez
• Grantee: Cristina Elisa Alvarez Martinez
• Principal researcher abroad: Thierry SOLDATI
• Institution abroad: Université de Genève, Switzerland
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated researchers: Elizabeth Bilsland ; Shaker Chuck Farah
• Associated research grant(s): 23/14811-2 - Dissecting the dynamics of the Xanthomonas citri - Dictyostelium discoideum interaction, AP.R SPRINT
• Associated scholarship(s): 22/15160-2 - In vivo characterization of the Xanthomonas citri - Dictyostelium discoideum dynamics and the function of candidate anti-eukaryotic effectors, BP.PD

Abstract

Bacterial secretion systems are transenvelope protein complexes that promote the translocation of effector proteins directly into target cells or the extracellular milieu, and thus play fundamental roles in environmental adaptation. Type VI secretion systems (T6SS) are widespread in Proteobacteria and target prokaryotic and/or eukaryotic cells, acting as antibacterial weapons or anti-hosts determinants, respectively. Our research group has described a T6SS of the phytopathogenic bacterium Xanthomonas citri pv. citri (Xc) that confers resistance to predation by the bacterivorous amoeba Dictyostelium discoideum (Dd), a hitherto unknown aspect of Xc physiology that possibly increases its environmental fitness. This project aims to dissect the molecular mechanisms involved in the Xc-Dd interactions, characterizing the role of the T6SS in Xc resistance to predation. We will use a combination of state-of-the-art microscopy techniques, biochemical and genetic tools to dissect the dynamics of the Xc-Dd interactions, identify protein effectors targeted to the eukaryotic cell, also characterizing their mode of action, and analyze signals that trigger T6SS gene expression and activation. Results from these studies will expand our understanding of the role of anti-eukaryotic T6SS, possibly revealing new effector functions and anti-host strategies, also contributing to the understanding of mechanisms used by Xc to survive and disseminate in the environment. (AU)