title: The Prc and RseP proteases control bacterial cell-surface signalling activity.
abstract: Extracytoplasmic function (ECF) sigma factors play a key role in the regulation of vital functions in the bacterial response to the environment. In Gram-negative bacteria, activity of these sigma factors is often controlled by cell-surface signalling (CSS), a regulatory system that also involves an outer membrane receptor and a transmembrane anti-sigma factor. To get more insight into the molecular mechanism behind CSS regulation, we have focused on the unique Iut system of Pseudomonas putida. This system contains a hybrid protein containing both a cytoplasmic ECF sigma domain and a periplasmic anti-sigma domain, apparently leading to a permanent interaction between the sigma and anti-sigma factor. We show that the Iut ECF sigma factor regulates the response to aerobactin under iron deficiency conditions and is activated by a proteolytic pathway that involves the sequential action of two proteases: Prc, which removes the periplasmic anti-sigma domain, and RseP, which subsequently removes the transmembrane domain and thereby generates the ECF active transcriptional form. We furthermore demonstrate the role of these proteases in the regulation of classical CSS systems in which the sigma and anti-sigma factors are two different proteins.
authors.affiliation: Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain; Section of Molecular Microbiology, Department of Molecular Cell Biology, VU University Amsterdam, Amsterdam, The Netherlands.
authors.forename: Karlijn C
authors.initials: KC
authors.lastname: Bastiaansen
authors.forename: Aurelia
authors.initials: A
authors.lastname: Ibañez
authors.forename: Juan L
authors.initials: JL
authors.lastname: Ramos
authors.forename: Wilbert
authors.initials: W
authors.lastname: Bitter
authors.forename: María A
authors.initials: MA
authors.lastname: Llamas
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006877:Hydroxamic Acids / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D019897:Periplasm / Q000378:metabolism; D059748:Proteolysis; D016958:Pseudomonas putida / Q000235:genetics* / Q000378:metabolism; D012808:Sigma Factor / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*
chemical_list: D006877:Hydroxamic Acids; D012808:Sigma Factor; C031819:aerobactin; D007501:Iron; D010450:Endopeptidases