title: Processing of cell-surface signalling anti-sigma factors prior to signal recognition is a conserved autoproteolytic mechanism that produces two functional domains.
abstract: Cell-surface signalling (CSS) enables Gram-negative bacteria to transduce an environmental signal into a cytosolic response. This regulatory cascade involves an outer membrane receptor that transmits the signal to an anti-sigma factor in the cytoplasmic membrane, allowing the activation of an extracytoplasmic function (ECF) sigma factor. Recent studies have demonstrated that RseP-mediated proteolysis of the anti-sigma factors is key to σ(ECF) activation. Using the Pseudomonas aeruginosa FoxR anti-sigma factor, we show here that RseP is responsible for the generation of an N-terminal tail that likely contains pro-sigma activity. Furthermore, it has been reported previously that this anti-sigma factor is processed in two separate domains prior to signal recognition. Here, we demonstrate that this process is common in these types of proteins and that the processing event is probably due to autoproteolytic activity. The resulting domains interact and function together to transduce the CSS signal. However, our results also indicate that this processing event is not essential for activity. In fact, we have identified functional CSS anti-sigma factors that are not cleaved prior to signal perception. Together, our results indicate that CSS regulation can occur through both complete and initially processed anti-sigma factors.
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, The Netherlands.
authors.forename: Karlijn C
authors.initials: KC
authors.lastname: Bastiaansen
authors.affiliation: Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain.
authors.forename: Joaquín R
authors.initials: JR
authors.lastname: Otero-Asman
authors.affiliation: Section of Molecular Microbiology, Department of Molecular Cell Biology, VU University, Amsterdam, The Netherlands.
authors.forename: Joen
authors.initials: J
authors.lastname: Luirink
authors.affiliation: Section of Molecular Microbiology, Department of Molecular Cell Biology, VU University, Amsterdam, The Netherlands.
authors.forename: Wilbert
authors.initials: W
authors.lastname: Bitter
authors.affiliation: Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain.
authors.forename: María A
authors.initials: MA
authors.lastname: Llamas
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D059647:Gene-Environment Interaction; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012808:Sigma Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D011956:Receptors, Cell Surface; D012808:Sigma Factor; C072460:foxR protein, bacteria