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Postexponential regulation of sin operon expression in Bacillus subtilis
Sasha H Shafikhani1, Ines Mandic-Mulec, Mark A Strauch
1Department of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720, USA.
Journal of Bacteriology
|December 26, 2001
Summary
Bacillus subtilis sporulation relies on sinIR operon proteins. Key regulators Spo0A and Hpr bind the sinIR P1 promoter, controlling gene expression during early sporulation.
Area of Science:
- Microbiology
- Molecular Biology
- Gene Regulation
Background:
- The sinIR operon is crucial for early Bacillus subtilis sporulation.
- Its gene products are essential for developmental transitions.
- Regulation occurs at the transcriptional level.
Purpose of the Study:
- To investigate the transcriptional regulation of the sinIR operon.
- To identify the regulatory proteins and their binding sites at the P1 promoter.
- To determine the RNA polymerase involved in sinIR transcription.
Main Methods:
- In vivo transcription studies.
- In vitro DNase I footprinting assays.
- Identification of sigma factors.
Main Results:
- Transcription of sinIR from the P1 promoter is induced at the end of exponential growth.
- Hpr represses P1 induction, while phosphorylated Spo0A induces it.
- Hpr, AbrB, and Spo0A bind to the P1 promoter region.
- The P1 promoter is transcribed by the sigma(A) form of RNA polymerase.
Conclusions:
- The sinIR operon's P1 promoter is a key regulatory node in Bacillus subtilis sporulation.
- Spo0A and Hpr act as critical trans-acting factors in controlling sinIR expression.
- Sigma(A)-RNA polymerase is responsible for transcribing the sinIR operon during early sporulation.