Functional Studies on Xanthomonas citri Type VI Secretion System and Gene Regulation by Alternative Sigma Factors

• Grant number: 18/01852-4
• Support Opportunities: Regular Research Grants
• Duration: June 01, 2018 - March 31, 2021
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Cristina Elisa Alvarez Martinez
• Grantee: Cristina Elisa Alvarez Martinez
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated researchers: Suzete Aparecida Lanza Destéfano
• Associated scholarship(s): 19/17185-0 - Studies on the mechanisms of Xanthomonas citri subsp. citri resistance against predation by Dictyostelium discoideum, BP.TT

Abstract

Bacterial type VI secretion systems (T6SS) are multiprotein complexes that translocate protein effectors and/or toxins to target cells, playing major roles in interspecies competition, virulence and environmental adaptation in several bacteria. Xanthomonas citri subsp. citri is the causative agent of citrus canker disease, infecting all citrus crops. Previous studies by our research group have demonstrated that the X. citri T6SS is required for resistance to predation by the soil amoeba Dictyostelium discoideum, which potentially have important impact on X. citri persistence and dissemination in the environment. This project will further characterize the molecular mechanisms involved in resistance to amoeba predation and the signaling pathways that promote activation of the T6SS in X. citri. For that, we will perform in vivo translocation assays and yeast two-hybrid assays to identify proteins secreted by the T6SS. Characterization of two X. citri alternative sigma factors named EcfK and EcfL has shown that EcfK is required for transcriptional activation of T6SS genes, while EcfL regulates a small set of genes of unknown function. Bacterial alternative sigma factors are important regulators of environmental responses in bacteria. To further characterize these regulators, we will identify the signaling pathway that activates EcfK and the function of EcfL in X. citri physiology. To reach these goals we will use several bacterial genetics and biochemical approaches, including phenotypic analysis of knock-out strains, transcriptional fusions to reporter genes and biochemical characterization of proteins of interest. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

SGRO, GERMAN G.; OKA, GABRIEL U.; SOUZA, DIORGE P.; CENENS, WILLIAM; BAYER-SANTOS, ETHEL; MATSUYAMA, BRUNO Y.; BUENO, NATALIA F.; DOS SANTOS, THIAGO RODRIGO; ALVAREZ-MARTINEZ, CRISTINA E.; SALINAS, ROBERTO K.; et al. Bacteria-Killing Type IV Secretion Systems. FRONTIERS IN MICROBIOLOGY, v. 10, MAY 21 2019. (17/17303-7, 18/01852-4, 17/02178-2)

BAYER-SANTOS, ETHEL; CESETI, LUCAS DE MORAES; FARAH, CHUCK SHAKER; ALVAREZ-MARTINEZ, CRISTINA ELISA. Distribution, Function and Regulation of Type 6 Secretion Systems of Xanthomonadales. FRONTIERS IN MICROBIOLOGY, v. 10, JUL 17 2019. (18/04553-8, 17/17303-7, 17/02178-2, 18/01852-4, 17/02318-9)

CESETI, LUCAS M.; DE SANTANA, ELIANE S.; RATAGAMI, CAMILA Y.; BARREIROS, YASMIN; LIMA, LIDIA DOS PASSOS; DUNGER, GERMAN; FARAH, CHUCK S.; ALVAREZ-MARTINEZ, CRISTINA E.. The Xanthomonas citri pv. citri Type VI Secretion System is Induced During Epiphytic Colonization of Citrus. Current Microbiology, v. 76, n. 10, p. 1105-1111, OCT 2019. (11/22571-4, 16/08400-6, 14/19720-6, 17/02318-9, 18/01852-4, 14/25261-4, 11/07777-5)