title: Role of fimV in type II secretion system-dependent protein secretion of Pseudomonas aeruginosa on solid medium.
abstract: Although classical type II secretion systems (T2SSs) are widely present in Gram-negative bacteria, atypical T2SSs can be found in some species. In Pseudomonas aeruginosa, in addition to the classical T2SS Xcp, it was reported that two genes, xphA and xqhA, located outside the xcp locus were organized in an operon (PaQa) which encodes the orphan PaQa subunit. This subunit is able to associate with other components of the classical Xcp machinery to form a functional hybrid T2SS. In the present study, using a transcriptional lacZ fusion, we found that the PaQa operon was more efficiently expressed (i) on solid LB agar than in liquid LB medium, (ii) at 25 °C than at 37 °C and (iii) at an early stage of growth. These results suggested an adaptation of the hybrid system to particular environmental conditions. Transposon mutagenesis led to the finding that vfr and fimV genes are required for optimal expression of the orphan PaQa operon in the defined growth conditions used. Using an original culturing device designed to monitor secretion on solid medium, the ring-plate system, we found that T2SS-dependent secretion of exoproteins, namely the elastase LasB, was affected in a fimV deletion mutant. Our findings led to the discovery of an interplay between FimV and the global regulator Vfr triggering the modulation of the level of Vfr and consequently the modulation of T2SS-dependent secretion on solid medium.
authors.affiliation: Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM-UPR9027), CNRS and Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: Gérard P F
authors.initials: GPF
authors.lastname: Michel
authors.affiliation: Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM-UPR9027), CNRS and Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Aguzzi
authors.affiliation: Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM-UPR9027), CNRS and Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Ball
authors.affiliation: Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM-UPR9027), CNRS and Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Soscia
authors.affiliation: Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM-UPR9027), CNRS and Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Bleves
authors.affiliation: Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM-UPR9027), CNRS and Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: Romé
authors.initials: R
authors.lastname: Voulhoux
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000235:genetics / Q000502:physiology*; D003470:Culture Media; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007763:Lac Operon; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D017384:Sequence Deletion
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D003470:Culture Media; D002373:Cyclic AMP Receptor Protein; D026901:Membrane Transport Proteins; C091090:Vfr protein, Pseudomonas aeruginosa; D008666:Metalloendopeptidases; C043859:pseudolysin, Pseudomonas aeruginosa