Mechanisms of regulation and transport of manganese and their relationship with the virulence of Chromobacterium violaceum

• Grant number: 23/03796-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: June 01, 2023
• End date: May 31, 2026
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: José Freire da Silva Neto
• Grantee: Maria Fernanda Cavenague Pereira
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 21/06894-0 - Bacterial transcription factors involved in metal homeostasis, oxidative stress and virulence: investigating how Chromobacterium violaceum switches from the environment to the host, AP.JP2

Abstract

The transition metal manganese (Mn) is an important micronutrient in the host-pathogen interaction, but still little studied in relation to other metals such as iron and zinc. During an infection, vertebrate hosts limit bacterial access to manganese by sequestering it in the protein calprotectin. Bacteria evade this nutritional immunity mechanism in different ways. In this project, we propose to study the mechanisms of manganese homeostasis in thebacterium Chromobacterium violaceum, an opportunistic human pathogen. Our groupdemonstrated the importance of iron and zinc in the virulence of C. violaceum, but the role of manganese has not yet been investigated. Genes differentially expressed in response to manganese will be identified by RNA sequencing (RNAseq) of the wild-type strain of C. violaceum grown in limitation or excess of this metal. These data will be validated by quantitative PCR. Null mutants will be obtained with deletion of specific genes identified by RNAseq or by in silico analysis as potentially involved in manganese homeostasis, focusing on transport systems for uptake or export of this metal. The mutants will be characterized in vitro for the growth profile, cellular manganese content, resistance to oxidative stress, and tolerance to calprotectin, and in vivo in a model of infection in mice. The data obtained in this project will contribute to understanding how C. violaceum maintains manganese homeostasis and what is the importance of this metal for the physiology and virulence of this bacterium. Considering the distinct repertoire of predicted manganese regulators and transporters in C. violaceum, this project has the potential to reveal new mechanisms of manganese homeostasis in bacteria and possible new targets for interference in bacterial virulence.