Unraveling the biological role of LsfA, a 1-Cys Prx involved in the Pseudomonas aeruginosa virulence

Author(s)

Rogério Luis Aleixo Silva

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2023-11-08

Examining board members

Luis Eduardo Soares Netto; Sayuri Miyamoto; Marcos Antonio de Oliveira; José Freire da Silva Neto

• Advisor: Luis Eduardo Soares Netto

Abstract

Pseudomonas aeruginosa is a ubiquitous, gamma-proteobacteria, which is the main cause of nosocomial infection among all pathogens related to pneumonia in the Intensive Care Unit. We are interested in the redox aspects involved in host-pathogen interactions. PaLsfA belongs to the peroxiredoxin (Prx) family and to the subgroup that contains only one catalytic cysteine (so-called 1-Cys Prx). Prxs are enzymes capable of removing peroxides (including peroxynitrite) at very high rates. As PaLsfA is related to the P. aeruginosa virulence we intended in the present thesis, further advance the characterization of this protein, regarding its biological roles in P. aeruginosa. We first evaluated the rate constant between ascorbate and PaLsfA, the only reductant of this protein until now. Also, the importance of some amino acids related to the reaction between them, which, surprisingly, for some mutants, increased the reactivity around ten times. By different microbiological approaches, we revealed the importance of PaLsfA for the bacterial defense against H2O2 and paraquat (a superoxide generator), but not against SIN-1 (peroxynitrite generator). Using the genetically encoded probe Hyper7 we revealed the capacity of PaLsfA protecting P. aeruginosa against H2O2 and the capacity of ascorbate to act as an intracellular reductant of PaLsfA in this bacterium. Additionally, we first described a phospholipase activity for a bacterial Prx, however the biological implication of this activity remains unclear. Finally, the capacity of PaLsfA influencing the inflammatory process in macrophages is a first description of a bacterial Prx influencing the host inflammatory response, correlating to its involvement with P. aeruginosa virulence. In this way, our findings can enlighten the understanding about how this protein affects the virulence of P. aeruginosai> and make possible future insights into inhibitory mechanisms. (AU)

• FAPESP's process: 20/00845-4 - Unraveling the biological role of LsfA, a 1-Cys Prx involved in the P. aeruginosa virulence
• Grantee: Rogério Luis Aleixo Silva
• Support Opportunities: Scholarships in Brazil - Doctorate