New response regulators involved in Pseudomonas aeruginosa virulence

• Grant number: 13/10385-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: December 01, 2013
• End date: January 31, 2017
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Regina Lúcia Baldini
• Grantee: Gilberto Hideo Kaihami
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Pseudomonas aeruginosa is a gamma proteobacterium that acts as an opportunistic pathogen in humans and it is intrinsically resistant to antibiotics. Among all infection sites, pulmonary infections in intensive care units patients are those with highest mortality rates. The ability of P. aeruginosa to adapt to diverse environments is in part due to the high proportion of regulatory genes in its genome. Among signaling pathways, the two-component systems allow bacteria to sense and respond properly to a series of conditions. Activation of two-component systems begins with an input signal that triggers the auto-phosphorylation of a histidine kinase sensor. The phosphoryl group is then transferred to a response regulator that, once phosphorylated, is able to mediate a response to the signal. There are more than 70 response regulators genes in P. aeruginosa strain PA14 but there are no reports of a global evaluation of their role in virulence, although a few two-component systems are well characterized, such as GacA/GacS. The first defense line in the lungs against P. aeruginosa infection corresponds to macrophages, which detect bacteria by Toll-like receptors that recognize pathogen molecular patterns like flagellin and lipopolysaccharide. This project aims to understand the involvement of the two-component regulatory systems in P. aeruginosa virulence. The involvement of the response regulators in virulence will be examined in vitro using J774 macrophages infected with P. aeruginosa mutants in response regulators´genes . Cytotoxicity, bacterial clearance and cytokine production will be evaluated in this model. Bacterial mutants will be phenotypically characterized regarding virulence-associated traits such as motility, growth in biofilms and production of pyocyanin. Attenuated mutants in the in vitro assays will be tested in vivo in a mouse acute pneumonia model. The two-component systems regulons will be determined by proteomics and/or transcriptomics. Since two-component systems are absent in humans, they represent potential targets for drug development and their understanding may provide important information to P. aeruginosa infections treatment.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

KAIHAMI, Gilberto Hideo. New response regulators involved in Pseudomonas aeruginosa virulence. 2018. Doctoral Thesis - Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) São Paulo.