Xanthomonas citri and Caedibacter taeniospiralis R-bodies: expression and structural characterization

• Grant number: 23/17618-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2024
• End date: May 31, 2025
• Field of knowledge: Biological Sciences - Biochemistry - Biochemistry of Microorganisms
• Principal Investigator: Shaker Chuck Farah
• Grantee: Raphaela Machado Campos Lopes
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/10577-0 - Biology of Bacteria and Bacteriophages Research Center, AP.CEPID

Abstract

R-bodies, or refractile bodies, are polymeric protein structures first characterized in the bacterium Caedibacter taeniospiralis. When exposed to acidic pH, R-bodies drastically change their conformation and size, going from a coiled ribbon of 0.5 µm to an extended one that can exceed 4 µm. The reb genes homologues, which encode the main components of R-bodies, are widely spread in the phylum Proteobacteria, including being present in the genome of Xanthomonas citri, a phytopathogen of economic importance in Brazil. Very little is known about the physiological functions carried out by R-bodies and no information is available regarding their role in the biology of bacteria from the order Xanthomonadales. In this project, we aim to study the R-bodies of X. citri through several techniques, including heterologous expression in Escherichia coli, purification and analysis in transmission electron microscopy (TEM) and also detecting possible conformational changes in the proteins in response to changes in the environment through absorbance, circular dichroism and fluorescence. Finally, the structure of C. taeniospiralis R-bodies will also be studied by cryoelectron microscopy, cryoelectron tomography and mass spectrometry.