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Mechanism of secretion of TcpF by the Vibrio cholerae toxin-coregulated pilus
Many bacteria possess dynamic filaments called Type IV pili (T4P) that perform diverse functions in colonization and dissemination, including host cell adhesion, DNA uptake, and secretion of protein substrates-exoproteins-from the periplasm to the extracellular space. The toxin-coregulated pilus (TC...
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Published in: | Proceedings of the National Academy of Sciences - PNAS 2023-04, Vol.120 (16), p.e2212664120-e2212664120 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites |
Online Access: | Get full text |
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Summary: | Many bacteria possess dynamic filaments called Type IV pili (T4P) that perform diverse functions in colonization and dissemination, including host cell adhesion, DNA uptake, and secretion of protein substrates-exoproteins-from the periplasm to the extracellular space. The
toxin-coregulated pilus (TCP) and the enterotoxigenic
CFA/III pilus each mediates export of a single exoprotein, TcpF and CofJ, respectively. Here, we show that the disordered N-terminal segment of mature TcpF is the export signal (ES) recognized by TCP. Deletion of the ES disrupts secretion and causes TcpF to accumulate in the
periplasm. The ES alone can mediate export of
FbpA by
in a T4P-dependent manner. The ES is specific for its autologous T4P machinery as CofJ bearing the TcpF ES is exported by
, whereas TcpF bearing the CofJ ES is not. Specificity is mediated by binding of the ES to TcpB, a minor pilin that primes pilus assembly and forms a trimer at the pilus tip. Finally, the ES is proteolyzed from the mature TcpF protein upon secretion. Together, these results provide a mechanism for delivery of TcpF across the outer membrane and release into the extracellular space. |
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ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.2212664120 |