Characterization of FimV and its involvement with polar definition in Xanthomonas citri

• Grant number: 25/09306-2
• Support Opportunities: Scholarships in Brazil - Master
• Start date: December 01, 2025
• End date: November 30, 2027
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Henrique Ferreira
• Grantee: Letícia Menegatti Calegari
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Associated research grant: 21/10577-0 - Biology of Bacteria and Bacteriophages Research Center, AP.CEPID

Abstract

Xanthomonas citri subsp. citri (X. citri), the etiological agent of citrus canker, has been extensively studied in terms of its epidemiology and pathology. However, its essential molecular systems remain limitedly understood. Previous studies have demonstrated that X. citri exhibits asymmetric chromosome segregation, similar to Caulobacter crescentus and Vibrio cholerae. This asymmetry is due to the ori-ter chromosome orientation pattern, in which the origin of replication (oriC) is positioned near one of the cell poles and the end of replication (ter) at the opposite pole. As a consequence of this arrangement, cellular components and proteins are unevenly distributed along the cell, resulting in cell polarity. This polarity is regulated by the action of proteins that are located at the cell poles and bind to regions close to the oriC, assisting the cells in pole recognition and in recruiting other molecules to form protein complexes. A protein homologous to HubP from Vibrio cholerae, named FimV, was identified in Xanthomonas citri. FimV has been described in Pseudomonas aeruginosa, where it functions as a polar organizing center, coordinating the localization and activities of Type IV pilus (T4P) components. In bacteria of the genus Vibrio, HubP controls the polar localization of the chromosomal replication origin, the chemotactic machinery and the flagellum. Therefore, this project intends to investigate the function and verify the essentiality of the gene encoding FimV in X. citri. For this, the gene deletion technique and a subcellular localization assay using GFP (green fluorescent protein) will be applied to confirm its polar localization. Furthermore, the immunoprecipitation technique will be used to identify FimV-GFP interactors in X. citri in order to explore the protein network that surrounds it. These data may confirm the involvement of FimV in pole marking in X. citri and contribute to the understanding of how this marking occurs.