title: Comparative Proteomic Profiling of Ehrlichia ruminantium Pathogenic Strain and Its High-Passaged Attenuated Strain Reveals Virulence and Attenuation-Associated Proteins.
abstract: The obligate intracellular bacterium Ehrlichia ruminantium (ER) causes heartwater, a fatal tick-borne disease in livestock. In the field, ER strains present different levels of virulence, limiting vaccine efficacy, for which the molecular basis remains unknown. Moreover, there are no genetic tools currently available for ER manipulation, thus limiting the knowledge of the genes/proteins that are essential for ER pathogenesis and biology. As such, to identify proteins and/or mechanisms involved in ER virulence, we performed the first exhaustive comparative proteomic analysis between a virulent strain (ERGvir) and its high-passaged attenuated strain (ERGatt). Despite their different behaviors in vivo and in vitro, our results from 1DE-nanoLC-MS/MS showed that ERGvir and ERGatt share 80% of their proteins; this core proteome includes chaperones, proteins involved in metabolism, protein-DNA-RNA biosynthesis and processing, and bacterial effectors. Conventional 2DE revealed that 85% of the identified proteins are proteoforms, suggesting that post-translational modifications (namely glycosylation) are important in ER biology. Strain-specific proteins were also identified: while ERGatt has an increased number and overexpression of proteins involved in cell division, metabolism, transport and protein processing, ERGvir shows an overexpression of proteins and proteoforms (DIGE experiments) involved in pathogenesis such as Lpd, AnkA, VirB9 and B10, providing molecular evidence for its increased virulence in vivo and in vitro. Overall, our work reveals that ERGvir and ERGatt proteomes are streamlined to fulfill their biological function (maximum virulence for ERGvir and replicative capacity for ERGatt), and we provide both pioneering data and novel insights into the pathogenesis of this obligate intracellular bacterium.
authors.affiliation: Instituto de Biologia Experimental e Tecnológica (iBET), Oeiras, Portugal.|Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-UNL), Oeiras, Portugal.|CIRAD, UMR CMAEE, F-97170, Petit-Bourg, Guadeloupe, France.|INRA, UMR1309 CMAEE, F-34398, Montpellier, France.
authors.forename: Isabel
authors.initials: I
authors.lastname: Marcelino
authors.affiliation: Instituto de Biologia Experimental e Tecnológica (iBET), Oeiras, Portugal.|Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-UNL), Oeiras, Portugal.
authors.forename: Miguel
authors.initials: M
authors.lastname: Ventosa
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-UNL), Oeiras, Portugal.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Pires
authors.affiliation: Proteome Informatics, Swiss Institute of Bioinformatics (SIB), Geneva, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Müller
authors.affiliation: Proteome Informatics, Swiss Institute of Bioinformatics (SIB), Geneva, Switzerland.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Lisacek
authors.affiliation: CIRAD, UMR CMAEE, F-34398, Montpellier, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Lefrançois
authors.affiliation: CIRAD, UMR CMAEE, F-97170, Petit-Bourg, Guadeloupe, France.|INRA, UMR1309 CMAEE, F-34398, Montpellier, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vachiery
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-UNL), Oeiras, Portugal.
authors.forename: Ana Varela
authors.initials: AV
authors.lastname: Coelho
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D016995:Ehrlichia ruminantium / Q000254:growth & development / Q000472:pathogenicity; D006031:Glycosylation; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D037521:Virulence Factors