Export of the pseudopilin XcpT of the Pseudomonas aeruginosa type II secretion system via the signal recognition particle-Sec pathway.
Type IV pilins and pseudopilins are found in various prokaryotic envelope protein complexes, including type IV pili and type II secretion machineries of gram-negative bacteria, competence systems of gram-positive bacteria, and flagella and sugar-binding structures in members of the archaeal kingdom. The precursors of these proteins have highly conserved N termini, consisting of a short, positively charged leader peptide, which is cleaved off by a dedicated peptidase during maturation, and a hydrophobic stretch of approximately 20 amino acid residues. Which pathway is involved in the inner membrane translocation of these proteins is unknown. We used XcpT, the major pseudopilin from the type II secretion machinery of Pseudomonas aeruginosa, as a model to study this process. Transport of an XcpT-PhoA hybrid was shown to occur in the absence of other Xcp components in P. aeruginosa and in Escherichia coli. Experiments with conditional sec mutants and reporter-protein fusions showed that this transport process involves the cotranslational signal recognition particle targeting route and is dependent on a functional Sec translocon.
Arts
Jorik
J
Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
van Boxtel
Ria
R
Filloux
Alain
A
Tommassen
Jan
J
Koster
Margot
M
D000251:Adenosine Triphosphatases / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism* / Q000502:physiology*; D004926:Escherichia coli / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism* / Q000502:physiology*; D021381:Protein Transport; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D018271:Signal Recognition Particle / Q000502:physiology*
D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle; C082104:XcpT protein, Pseudomonas aeruginosa; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins