title: The type II secretion system (Xcp) of Pseudomonas putida is active and involved in the secretion of phosphatases.
abstract: The genome of the Gram-negative bacterium Pseudomonas putida harbours a complete set of xcp genes for a type II protein secretion system (T2SS). This study shows that expression of these genes is induced under inorganic phosphate (Pi ) limitation and that the system enables the utilization of various organic phosphate sources. A phosphatase of the PhoX family, previously designated UxpB, was identified, which was produced under low Pi conditions and transported across the cell envelope in an Xcp-dependent manner demonstrating that the xcp genes encode an active T2SS. The signal sequence of UxpB contains a twin-arginine translocation (Tat) motif as well as a lipobox, and both processing by leader peptidase II and Tat dependency were experimentally confirmed. Two different tat gene clusters were detected in the P. putida genome, of which one, named tat-1, is located adjacent to the uxpB and xcp genes. Both Tat systems appeared to be capable of transporting the UxpB protein. However, expression of the tat-1 genes was strongly induced by low Pi levels, indicating a function of this system in survival during Pi starvation.
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, 3584 CH, Utrecht, The Netherlands.
authors.forename: Florian
authors.initials: F
authors.lastname: Putker
authors.forename: Ria
authors.initials: R
authors.lastname: Tommassen-van Boxtel
authors.forename: Michiel
authors.initials: M
authors.lastname: Stork
authors.forename: José J
authors.initials: JJ
authors.lastname: Rodríguez-Herva
authors.forename: Margot
authors.initials: M
authors.lastname: Koster
authors.forename: Jan
authors.initials: J
authors.lastname: Tommassen
mesh_terms: D058947:Bacterial Secretion Systems / Q000235:genetics*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism*; D021381:Protein Transport; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism; D016958:Pseudomonas putida / Q000201:enzymology* / Q000235:genetics*
chemical_list: D058947:Bacterial Secretion Systems; D026901:Membrane Transport Proteins; D010710:Phosphates; D010744:Phosphoric Monoester Hydrolases