title: Identification of a new quorum-sensing-controlled virulence factor in Erwinia carotovora subsp. atroseptica secreted via the type II targeting pathway.
abstract: Two-dimensional polyacrylamide gel electrophoresis of the secreted proteins of Erwinia carotovora subsp. atroseptica revealed a low-abundance protein that was identified by mass spectrometry as a homologue of a Xanthomonas campestris avirulence protein with unknown function. The predicted Svx protein has an N-terminal signal sequence and zinc binding-region signature, and the mature protein is post-translationally modified. A 2D difference gel electrophoresis (DIGE) showed that the protein is secreted by the type II (out) secretion apparatus, which is also responsible for the secretion of the major known virulence factors, PelC and CelV. Transcription of the svx gene is under N-acyl-homoserine lactone-mediated quorum-sensing control. The svx gene was inactivated by transposon insertion. The mutant showed a decrease in virulence in potato plant assays, demonstrating a role for Svx in the pathogenicity of E. carotovora subsp. atroseptica. These results show that Svx is a previously unidentified virulence determinant which is secreted by the out machinery and is regulated by quorum sensing, two systems employed by several other virulence factors. Thus, the type II secretory machine is a conduit for virulence factors other than the main pectinnases and cellulase in E. carotovora subsp. atroseptica.
authors.affiliation: Department of Biochemistry, University of Cambridge, CB2 1QW, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Corbett
authors.forename: Sam
authors.initials: S
authors.lastname: Virtue
authors.forename: Kenneth
authors.initials: K
authors.lastname: Bell
authors.forename: Paul
authors.initials: P
authors.lastname: Birch
authors.forename: Tom
authors.initials: T
authors.lastname: Burr
authors.forename: Lysbeth
authors.initials: L
authors.lastname: Hyman
authors.forename: Kathryn
authors.initials: K
authors.lastname: Lilley
authors.forename: Susannah
authors.initials: S
authors.lastname: Poock
authors.forename: Ian
authors.initials: I
authors.lastname: Toth
authors.forename: George
authors.initials: G
authors.lastname: Salmond
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D016297:Mutagenesis, Site-Directed; D016973:Pectobacterium carotovorum / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D030821:Plants, Genetically Modified; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D011198:Solanum tuberosum / Q000235:genetics / Q000382:microbiology; D014774:Virulence; D037521:Virulence Factors / Q000032:analysis*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D037521:Virulence Factors