Temporal expression of the Bacillus subtilis secA gene, encoding a central component of the preprotein translocase.
In Bacillus subtilis, the secretion of extracellular proteins strongly increases upon transition from exponential growth to the stationary growth phase. It is not known whether the amounts of some or all components of the protein translocation apparatus are concomitantly increased in relation to the increased export activity. In this study, we analyzed the transcriptional organization and temporal expression of the secA gene, encoding a central component of the B. subtilis preprotein translocase. We found that secA and the downstream gene (prfB) constitute an operon that is transcribed from a vegetative (sigmaA-dependent) promoter located upstream of secA. Furthermore, using different independent methods, we found that secA expression occurred mainly in the exponential growth phase, reaching a maximal value almost precisely at the transition from exponential growth to the stationary growth phase. Following to this maximum, the de novo transcription of secA sharply decreased to a low basal level. Since at the time of maximal secA transcription the secretion activity of B. subtilis strongly increases, our results clearly demonstrate that the expression of at least one of the central components of the B. subtilis protein export apparatus is adapted to the increased demand for protein secretion. Possible mechanistic consequences are discussed.
Herbort
M
M
Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
Klein
M
M
Manting
E H
EH
Driessen
A J
AJ
Freudl
R
R
D000251:Adenosine Triphosphatases / Q000235:genetics*; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D001426:Bacterial Proteins / Q000235:genetics*; D001692:Biological Transport; D002874:Chromosome Mapping; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D007700:Kinetics; D026901:Membrane Transport Proteins; D009876:Operon; D010454:Peptide Termination Factors / Q000235:genetics; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013171:Spores, Bacterial; D013997:Time Factors; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D010454:Peptide Termination Factors; D012329:RNA, Bacterial; D012333:RNA, Messenger; D000069816:SEC Translocation Channels; C041460:peptide chain termination release factor 2; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins