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Crystal structure of the SarS protein from Staphylococcus aureus
Ronggui Li1, Adhar C Manna, Shaodong Dai
1Integrated Department of Immunology, National Jewish Medical and Research Center, and Department of Pharmacology, Biomolecular Structure Program, School of Medicine, University of Colorado Health Science Center, Denver, Colorado 80206, USA.
Journal of Bacteriology
|July 3, 2003
Summary
The crystal structure of Staphylococcus aureus SarS reveals a unique winged-helix DNA-binding protein. This finding advances understanding of virulence gene regulation and the SarA/SarS/MarR protein family.
Area of Science:
- Microbiology
- Structural Biology
- Molecular Genetics
Background:
- Bacterial virulence gene expression in Staphylococcus aureus is governed by regulatory loci like sarA and agr.
- The sarS gene encodes a DNA-binding protein that activates protein A (spa) expression.
- The agr locus appears to repress spa by suppressing sarS transcription.
Purpose of the Study:
- To elucidate the three-dimensional structure of the SarS protein.
- To compare the structure of SarS with related regulatory proteins SarA, SarR, and MarR.
- To propose a mechanism for transcriptional regulation mediated by SarS.
Main Methods:
- X-ray crystallography was employed to determine the structure of SarS at 2.2 A resolution.
- Structural comparisons were made with SarR, SarA, and MarR proteins.
- Sequence alignments were performed to identify conserved features and evolutionary relationships.
Main Results:
- The SarS structure reveals two winged-helix DNA-binding domains connected by a loop, similar to SarR and SarA.
- The DNA-binding surface of SarS is positively charged, while opposite surfaces are negatively charged.
- MarR proteins share structural similarities with SarR and SarS, suggesting a common DNA-binding mode within the winged-helix family.
Conclusions:
- SarS represents a distinct subfamily within the winged-helix protein family, alongside SarA and MarR.
- Structural insights into SarS provide a basis for understanding its role in Staphylococcus aureus virulence regulation.
- The study proposes a model for transcriptional regulation involving SarS and related proteins.