J. Bacteriol., Sep 1996, 5144-5152, Vol 178, No. 17
Copyright © 1996, American Society for Microbiology

Plasmid-amplified comS enhances genetic competence and suppresses sinR in Bacillus subtilis

L Liu, MM Nakano, OH Lee and P Zuber
Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, Shreveport, USA.

The establishment of genetic competence in Bacillus subtilis is controlled by a vast signal transduction network involving the products of genes that function in several postexponential-phase processes. Two of these proteins, SinR and DegU, serve as molecular switches that influence a cell's decision to undergo either sporulation or genetic competence development. In order to determine the roles of SinR and DegU in competence control, multicopy suppression experiments with plasmid-amplified comS, SinR, and degU genes were undertaken. Multicopy comS was found to elevate competence gene transcription and transformation efficiency in both wild-type and sinR mutant cells but not in degU mutant cells. Multicopy degU failed to suppress comS or sinR mutations. No suppression of comS or degU by multicopy sinR was observed. The expression of a comS'::'lacZ translational fusion and srf- lacZ operon fusion was examined in sinR cells and cells bearing plasmid- amplified sinR. The expression of comS'::'lacZ gene fusion was reduced by the sinR mutation, but both comS'::'lacZ and srf-lacZ were repressed by multicopy sinR. Cells bearing plasmid-amplified sinR were poorly competent. These results suggest that sinR is required for optimal comS expression but not transcription from the srf promoter and that SinR at high concentrations represses srf transcription initiation.

This article has been cited by other articles:

• Hamoen, L. W., Venema, G., Kuipers, O. P. (2003). Controlling competence in Bacillus subtilis: shared use of regulators. Microbiology 149: 9-17 [Abstract] [Full Text]  
• Piazza, F., Tortosa, P., Dubnau, D. (1999). Mutational Analysis and Membrane Topology of ComP, a Quorum-Sensing Histidine Kinase of Bacillus subtilis Controlling Competence Development. J. Bacteriol. 181: 4540-4548 [Abstract] [Full Text]  
• Liu, J., Zuber, P. (1998). A Molecular Switch Controlling Competence and Motility: Competence Regulatory Factors ComS, MecA, and ComK Control sigma D-Dependent Gene Expression in Bacillus subtilis. J. Bacteriol. 180: 4243-4251 [Abstract] [Full Text]  
• Eppelmann, K., Doekel, S., Marahiel, M. A. (2001). Engineered Biosynthesis of the Peptide Antibiotic Bacitracin in the Surrogate Host Bacillus subtilis. J. Biol. Chem. 276: 34824-34831 [Abstract] [Full Text]