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CysB in the Multiverse of Functions: Regulatory Roles in Cysteine Biosynthesis and Beyond
1Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
Frontiers in Bioscience (Landmark Edition)
|September 8, 2025
Summary
CysB, a bacterial transcriptional regulator, controls sulfur and cysteine genes. Its DNA binding and effector roles show divergence, regulating diverse genes beyond sulfur metabolism.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- CysB is a LysR-type transcriptional regulator (LTTR) essential for sulfur and cysteine metabolism in bacteria.
- LTTRs typically function as homotetramers with DNA-binding and effector-binding domains.
Purpose of the Study:
- To review CysB's established roles in regulating the cysteine regulon.
- To interpret CysB's DNA binding modes based on recent structural data.
- To explore the functional divergence of CysB orthologs.
Main Methods:
- Structural analysis of full-length CysB.
- Review of established CysB functions.
- Comparative analysis of CysB orthologs and their regulons.
Main Results:
- CysB functions as a homotetramer with distinct DNA-binding and effector-binding domains.
- DNA binding is consistent with the 'sliding dimer' model common to LTTRs.
- CysB orthologs exhibit effector-independent regulation and control genes unrelated to sulfur metabolism, such as hslJ and pqsR.
Conclusions:
- CysB plays a crucial role in sulfur and cysteine homeostasis.
- Structural insights support the 'sliding dimer' model for CysB DNA binding.
- CysB orthologs have evolved diverse regulatory functions beyond sulfur metabolism, integrating into various gene networks.
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