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Multiple factors regulate the expression of sufCDSUB in Streptococcus mutans
Kassapa Ellepola1, Lauren C Guillot1, Bradley Comeaux1
1Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States.
Frontiers in Cellular and Infection Microbiology
|December 12, 2024
Summary
The sufCDSUB gene cluster in S. mutans is regulated by multiple factors, including PerR and CysR, in response to iron and cysteine availability. This study elucidates the regulatory mechanisms controlling iron-sulfur cluster assembly in this bacterium.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- The sufCDSUB gene cluster is essential for iron-sulfur (Fe-S) cluster assembly in *S. mutans*.
- Fe-S cluster homeostasis is critical for bacterial physiology and adaptation to environmental stress.
Purpose of the Study:
- To investigate the regulatory factors controlling the expression of the *sufCDSUB* gene cluster in *S. mutans*.
- To elucidate the roles of PerR and CysR in the regulation of Fe-S cluster assembly.
Main Methods:
- Luciferase reporter fusion assays to quantify promoter activity.
- Electrophoretic gel mobility shift assays (EMSA) to assess protein-DNA interactions.
- *In vitro* transcription assays (IVT) to determine transcriptional regulation.
Main Results:
- Deletion of *perR* significantly increased *sufCDSUB* promoter activity, indicating PerR acts as a repressor.
- Mutagenesis of the PerR-binding site confirmed its role in repression.
- Cysteine addition strongly induced *sufCDSUB* expression, while deletion of *cysR* reduced it, highlighting CysR's role as an activator.
- Both PerR and CysR directly bind to the *sufCDSUB* promoter region.
Conclusions:
- *S. mutans* employs a complex regulatory network involving PerR and CysR to control *sufCDSUB* expression.
- Regulation is responsive to environmental cues such as iron and cysteine availability.
- These findings provide insights into the intricate mechanisms governing Fe-S cluster biogenesis and its importance in bacterial adaptation.
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