The Twin-Arginine Signal Peptide of Bacillus subtiis YwbN Can Direct either Tat- or Sec-Dependent Secretion of Different Cargo Proteins: Secretion of Active Subtilisin via the B. subtilis Tat Pathway

• Published in: Applied and environmental microbiology 2008-12, Vol.74 (24), p.7507
• Main Authors: Kolkman, Marc A B, van der Ploeg, René, Bertels, Michael, van Dijk, Maurits, van der Laan, Joop, van Dijl, Jan Maarten, Ferrari, Eugenio
• Format: Article
• Language: English
• Subjects: Amino acids; Gram-positive bacteria; Microbiology; Peptides; Protein folding; Proteins; Signal transduction
• ISSN: 0099-2240; 1098-5336

Proteins that are produced for commercial purposes in Bacillus subtilis are commonly secreted via the Sec pathway. Despite its high secretion capacity, the secretion of heterologous proteins via the Sec pathway is often unsuccessful. Alternative secretion routes, like the Tat pathway, are therefore of interest. Two parallel Tat pathways with distinct specificities have previously been discovered in B. subtilis. To explore the application potential of these Tat pathways, several commercially relevant or heterologous model proteins were fused to the signal peptides of the known B. subtilis Tat substrates YwbN and PhoD. Remarkably, the YwbN signal peptide directed secretion of active subtilisin, a typical Sec substrate, via the B. subtilis TatAyCy route. In contrast, the same signal peptide directed Tat-independent secretion of the Bacillus licheniformis α-amylase (AmyL). Moreover, the YwbN signal peptide directed secretion of SufI, an Escherichia coli Tat substrate, in a Tat-independent manner, most likely via Sec. Our results suggest that cytoplasmic protein folding prior to translocation is probably a major determinant of Tat-dependent protein secretion in B. subtilis, as is the case with E. coli. We conclude that future applications for the Tat system of B. subtilis will most likely involve commercially interesting proteins that are Sec incompatible. [PUBLICATION ABSTRACT]