Pilus formation and protein secretion by the same machinery in Escherichia coli.
The secreton (type II secretion) and type IV pilus biogenesis branches of the general secretory pathway in Gram-negative bacteria share many features that suggest a common evolutionary origin. Five components of the secreton, the pseudopilins, are similar to subunits of type IV pili. Here, we report that when the 15 genes encoding the pullulanase secreton of Klebsiella oxytoca were expressed on a high copy number plasmid in Escherichia coli, one pseudopilin, PulG, was assembled into pilus-like bundles. Assembly of the 'secreton pilus' required most but not all of the secreton components that are essential for pullulanase secretion, including some with no known homologues in type IV piliation machineries. Two other pseudopilins, pullulanase and two outer membrane-associated secreton components were not associated with pili. Thus, PulG is probably the major component of the pilus. Expression of a type IV pilin gene, the E.coli K-12 gene ppdD, led to secreton-dependent incorporation of PpdD pilin into pili without diminishing pullulanase secretion. This is the first demonstration that pseudopilins can be assembled into pilus-like structures.
Sauvonnet
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Unité de Génétique Moléculaire (CNRS URA 1773) and Station Centrale de Microscopie Electronique, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France. max@pasteur.fr
Vignon
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G
Pugsley
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AP
Gounon
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P
D001426:Bacterial Proteins / Q000502:physiology*; D004926:Escherichia coli / Q000502:physiology* / Q000648:ultrastructure*; D010861:Fimbriae, Bacterial / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D015398:Signal Transduction
D001426:Bacterial Proteins