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Published on: August 5, 2016
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Phenotypes controlled by the Brucella abortus two component system BvrR/BvrS are differentially impacted by BvrR
Pamela Altamirano-Silva1, Jazmín Meza-Torres1, Ana Mariel Zúñiga-Pereira1
1Centro de Investigación en Enfermedades Tropicales, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica.
Frontiers in Microbiology
|May 26, 2023
Summary
The Brucella abortus BvrR/BvrS system regulates virulence. Unphosphorylated BvrR controls specific genes, impacting bacterial survival and virulence factor expression differently than phosphorylated BvrR.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Brucella abortus is a zoonotic pathogen requiring intracellular survival for virulence.
- The BvrR/BvrS two-component system regulates essential virulence factors like the type IV secretion system (VirB) and VjbR.
- BvrR phosphorylation is linked to DNA binding and gene transcription control, influencing membrane homeostasis and intracellular survival.
Purpose of the Study:
- To investigate the role of BvrR phosphorylation status in regulating BvrRS-controlled phenotypes and gene expression.
- To differentiate the regulatory mechanisms of phosphorylated versus unphosphorylated BvrR.
- To understand how BvrR phosphorylation impacts bacterial virulence and membrane characteristics.
Main Methods:
- Generated dominant positive and negative BvrR variants mimicking phosphorylated and unphosphorylated states.
- Introduced wild-type and variant BvrR into a BvrR-negative Brucella abortus strain.
- Assessed BvrRS-controlled phenotypes (polymyxin resistance, Omp25 expression, intracellular survival) and protein expression (VjbR, VirB).
- Performed promoter interaction studies and global transcriptional analysis.
Main Results:
- BvrR phosphorylation status differentially affects gene transcription.
- Dominant positive and wild-type BvrR restored polymyxin resistance and Omp25 expression.
- Both wild-type and dominant positive BvrR, along with the dominant negative variant, restored intracellular survival, VjbR, and VirB expression.
- Dominant negative BvrR showed specific promoter interactions with vjbR but not omp25, indicating distinct regulatory roles.
Conclusions:
- BvrR employs diverse strategies for transcriptional control based on its phosphorylation state.
- Unphosphorylated BvrR directly influences the expression of a subset of virulence-related genes.
- The BvrR/BvrS system's regulation is complex, with phosphorylation status dictating specific gene targets and downstream phenotypes.
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