title: Virulence of Erwinia amylovora, a prevalent apple pathogen: Outer membrane proteins and type III secreted effectors increase fitness and compromise plant defenses.
abstract: Until now, no data are available on the outer membrane (OM) proteome of Erwinia amylovora, a Gram-negative plant pathogen, causing fire blight in most of the members of the Rosaceae family. Since the OM forms the interface between the bacterial cell and its environment it is in direct contact with the host. Additionally, the type III secretion system, embedded in the OM, is a pathogenicity factor of E. amylovora. To assess the influence of the OM composition and the secretion behavior on virulence, a 2D-DIGE analysis and gene expression profiling were performed on a high and lower virulent strain, both in vitro and in planta. Proteome data showed an increase in flagellin for the lower virulent strain in vitro, whereas, in planta several interesting proteins were identified as being differently expressed between both the strains. Further, gene expression of nearly all type III secreted effectors was elevated for the higher virulent strain, both in vitro and in planta. As a first, we report that several characteristics of virulence can be assigned to the OM proteome. Moreover, we demonstrate that secreted proteins prove to be the important factors determining differences in virulence between the strains, otherwise regarded as homogeneous on a genome level.
authors.affiliation: Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Michelle
authors.initials: M
authors.lastname: Holtappels
authors.affiliation: School of Life Sciences, Biomedical Research Institute, Hasselt University and Transnational University Limburg, Hasselt, Belgium.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Noben
authors.affiliation: Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Diepenbeek, Belgium. roland.valcke@uhasselt.be.
authors.forename: Roland
authors.initials: R
authors.lastname: Valcke
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D044084:Erwinia amylovora / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D027845:Malus / Q000382:microbiology* / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology*; D057825:Two-Dimensional Difference Gel Electrophoresis; D000069296:Type III Secretion Systems / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D000069296:Type III Secretion Systems
keywords: 2D-DIGE; Erwinia amylovora; Fire blight; Microbiology; Outer membrane proteome; Type III secreted proteins