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Structural basis for the function of stringent starvation protein a as a transcription factor
Anne-Marie Hansen1, Yijun Gu, Mi Li
1Transcription Control Section, Gene Regulation and Chromosome Biology Laboratory, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702, USA.
The Journal of Biological Chemistry
|March 1, 2005
Summary
Stringent starvation protein A (SspA) is crucial for bacterial stress response and phage development. Its crystal structure reveals a pocket important for protein interactions, essential for acid resistance and phage P1 growth.
Area of Science:
- Microbiology
- Structural Biology
- Bacteriology
Background:
- Stringent starvation protein A (SspA) in Escherichia coli activates transcription for phage P1 lytic development and is vital for stationary phase acid tolerance.
- Yersinia pestis SspA shares high sequence identity and functional complementarity with E. coli SspA.
Purpose of the Study:
- To determine the crystal structure of Yersinia pestis SspA.
- To investigate the functional roles of SspA's structural features, including flexible regions and a conserved surface pocket, in bacterial acid resistance and phage P1 transcription activation.
Main Methods:
- X-ray crystallography was used to determine the SspA structure.
- Functional analysis involved creating and testing deletion and site-directed mutants of SspA in E. coli for acid resistance and phage P1 promoter activity.
Main Results:
- The crystal structure revealed SspA adopts a glutathione S-transferase (GST)-like fold but lacks GST activity.
- Flexible regions (N/C termini, alpha2-helix) were found to be non-critical for function.
- A conserved surface pocket is crucial for both transcriptional activation of the phage P1 late promoter and E. coli acid resistance, suggesting a role in protein-protein interactions.
Conclusions:
- The surface pocket of SspA is a key functional domain mediating protein-protein interactions essential for its roles in phage development and bacterial stress adaptation.
- SspA orthologs exhibit conserved functions in acid resistance across different bacterial species.