Characterization of the response to zinc intoxication in Chromobacterium violaceum

• Grant number: 25/00435-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: December 01, 2025
• End date: October 31, 2028
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: José Freire da Silva Neto
• Grantee: Sergio Pereira Lima Neto
• 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

Zinc is a transition metal essential for living organisms, including bacteria, due to its structural, regulatory, and catalytic functions in numerous proteins. However, in excess, zinc is toxic to cells by causing erroneous metallation (mismetallation) of proteins, which can lead to the blocking of metabolic pathways and imbalance in the homeostasis of other metals. In infection contexts, the immune system limits or intoxicates bacteria with zinc. This project aims to discover and characterize new genes and pathways involved in the zinc intoxication response in Chromobacterium violaceum, an opportunistic pathogen capable of causing severe infections in humans. For this, we will use genetic approaches and global gene expression profiling of C. violaceum exposed to excess zinc. A screening of transposon mutants susceptible to excess zinc and Sanger sequencing of the transposon insertion site should reveal genes important for zinc resistance. The isolation of spontaneous mutants resistant to excess zinc in the zntA mutant, which accumulates this metal, followed by NGS sequencing of some isolates, should reveal intracellular targets of zinc intoxication in C. violaceum. The global transcriptional response to zinc excess will be determined by RNAseq and validated by RT-qPCR. Additionally, null mutants of genes of interest will be generated and characterized in terms of growth, virulence, and metal content. The results of this project aim to elucidate how zinc intoxication and resistance occur in C. violaceum, which could contribute to revealing new therapeutic intervention targets against bacterial pathogens.