Role of type II secretion system in physiology and virulence of Chromobacterium violaceum

• Grant number: 18/03351-2
• Support type: Scholarships in Brazil - Doctorate
• Effective date (Start): January 01, 2019
• Effective date (End): December 31, 2021
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal researcher: José Freire da Silva Neto
• Grantee: Kelly Cristina Martins Barroso
• Home Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Secretion systems are specialized nanomachines for protein export through the bacterial cell envelope. The type II secretion system (T2SS) is utilized by many Gram-negative bacteria to translocate folded proteins from the periplasm to the extracellular milieu, including various toxins and degrading enzymes. Chromobacterium violaceum, an opportunistic human pathogen commonly found in the environment, has an operon of 12 genes encoding a potential T2SS. Although it is known that C. violaceum secretes exoproteins, the secretion mechanism is still unknown. In this work, we intend to characterize the T2SS of C. violaceum, focusing on the discovery of its substrates and how it is regulated. For this, we will construct mutant strains with single gene deletion or deletion of the entire T2SS operon. These mutant strains will be characterized by biofilm formation assays and determination of chitinase, protease, lecithinase, lipase and hemolysin activities. The involvement of T2SS in virulence will be analyzed in a mice infection model. The identification of T2SS-dependent secreted proteins will be done through proteomic analysis, comparing the secretome of the wide type and mutant strains. The regulation of the T2SS will be investigated by analyzing the expression of the T2SS operon promoter in luciferase reporter system. The results of this project should highlight the role of T2SS for adaptation and survival of C. violaceum in the environment and in the host. (AU)