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Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria
Published on: February 23, 2014
The pneumococcal MgaSpn virulence transcriptional regulator generates multimeric complexes on linear double-stranded
Virtu Solano-Collado1, Rudi Lurz, Manuel Espinosa
1Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, E-28040 Madrid, Spain.
Nucleic Acids Research
|June 1, 2013
Summary
The MgaSpn regulator in Streptococcus pneumoniae binds DNA differently based on its location. This finding provides new insights into how this virulence factor controls gene expression.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- The MgaSpn transcriptional regulator is crucial for Streptococcus pneumoniae virulence.
- MgaSpn belongs to the Mga/AtxA family of global regulators.
- MgaSpn activates the P1623B promoter, which is divergent from its own Pmga promoter, requiring a specific 70-bp region (PB activation region).
Purpose of the Study:
- To investigate the DNA-binding properties and specificity of the MgaSpn protein.
- To elucidate the mechanism by which MgaSpn regulates gene expression in Streptococcus pneumoniae.
Main Methods:
- Purification of untagged MgaSpn protein.
- Gel retardation and footprinting assays to analyze DNA binding.
- Electron microscopy to visualize protein-DNA complexes.
Main Results:
- Purified MgaSpn exists as dimers in solution.
- MgaSpn binds the PB activation region when internal on DNA, but prefers the Pmga promoter when at a DNA end.
- MgaSpn binding leads to the formation of multimeric complexes and spreads along adjacent DNA.
- Electron microscopy confirmed PB activation region as the preferred internal target and visualized DNA-protein interactions.
Conclusions:
- MgaSpn exhibits distinct DNA-binding preferences based on DNA end accessibility.
- The protein's ability to spread along DNA suggests complex regulatory mechanisms.
- MgaSpn may recognize specific DNA conformations for binding specificity, impacting Streptococcus pneumoniae virulence.
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