Investigating FimX protein's role in cell division in bacteria Pseudomonas aeruginosa

• Grant number: 25/06540-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Biological Sciences - Biochemistry - Biochemistry of Microorganisms
• Principal Investigator: Regina Lúcia Baldini
• Grantee: Bárbara Macarini Leite
• 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

Antimicrobial resistance has become an expressive and urgent global health matter that has prompted government agencies around the world to join efforts in studying this issue and searching for new drugs. Pseudomonas aeruginosa is a gamma-proteobacteria that is part of the high-priority group of resistant microorganisms, and consists of an opportunistic pathogen responsible mainly for hospital infections and lung infections in patients with Cystic Fibrosis (CF).An important virulence factor of P. aeruginosa is the type IV pilus (T4P), a filamentous structure responsible for cell adherence and twitching motility. The assembly of this appendage depends on the second messenger c-di-GMP, which controls the transition between a free-living and a sessile lifestyle, in addition to the establishment of biofilms (associated with chronic infections and closely related to antimicrobial resistance). The FimX protein, which has degenerate GGDEF and EAL domains - of diguanylate cyclase and phosphodiesterase activities, respectively - binds with high-affinity to c-di-GMP. This causes conformational changes, resulting in the protein activity over the T4P machinery: FimX binds to the ATPase protein PilB, which acts as a pilus extension motor, and enhances its activity. Like T4P, FimX has a polar localization in the cell, which may indicate an interaction with the diguanylate cyclase responsible for the c-di-GMP pool at the bacterial poles, called DgcP. Preliminary results with ¿fimX mutants, constructed to test this hypothesis, showed relevant differences from data found in the existing literature. Thus, the aim of this project is to complement the deletion mutants by expression of FimX from a single copy of the gene integrated at chromosomal site, in order to deepen the understanding of FimX's role in P. aeruginosa.