title: Polar secretion of proteins via the Xcp type II secretion system in Pseudomonas aeruginosa.
abstract: The subcellular localization of the major type II secretion system of Pseudomonas aeruginosa, the Xcp system, was studied microscopically using a biarsenical ligand that becomes fluorescent upon binding to a tetracysteine motif (Lumio tag), which was fused to several Xcp components. Fusion of the Lumio tag to the C termini of the XcpR and XcpS proteins did not affect the functionality of these proteins. Fluorescence microscopy showed that they were predominantly localized to the poles of P. aeruginosa cells, when produced at levels comparable to chromosomally encoded XcpR and XcpS. In most labelled cells, the proteins were found at one of the poles, although bipolar localization was also observed. When produced in the absence of other Xcp components, labelled XcpS was still found to locate at the poles, whereas XcpR was evenly distributed in the cell. These data suggest that XcpS, but not XcpR, contains information required for polar localization. The polar location of the Xcp machinery was further confirmed by the visualization of protease secretion with an intramolecularly quenched casein conjugate.
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands.
authors.forename: Freya
authors.initials: F
authors.lastname: Senf
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Tommassen
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands.
authors.forename: Margot
authors.initials: M
authors.lastname: Koster
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism* / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D049452:Green Fluorescent Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010196:Pancreatic Elastase / Q000378:metabolism; D010957:Plasmids; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; C082573:xcpR protein, Pseudomonas aeruginosa; D049452:Green Fluorescent Proteins; D010450:Endopeptidases; D010196:Pancreatic Elastase; C087822:alkaline protease