title: Profiling the secretome and extracellular proteome of the potato late blight pathogen Phytophthora infestans.
abstract: Oomycetes are filamentous organisms that cause notorious diseases, several of which have a high economic impact. Well known is Phytophthora infestans, the causal agent of potato late blight. Previously, in silico analyses of the genome and transcriptome of P. infestans resulted in the annotation of a large number of genes encoding proteins with an N-terminal signal peptide. This set is collectively referred to as the secretome and comprises proteins involved in, for example, cell wall growth and modification, proteolytic processes, and the promotion of successful invasion of plant cells. So far, proteomic profiling in oomycetes was primarily focused on subcellular, intracellular or cell wall fractions; the extracellular proteome has not been studied systematically. Here we present the first comprehensive characterization of the in vivo secretome and extracellular proteome of P. infestans. We have used mass spectrometry to analyze P. infestans proteins present in seven different growth media with mycelial cultures and this resulted in the consistent identification of over two hundred proteins. Gene ontology classification pinpointed proteins involved in cell wall modifications, pathogenesis, defense responses, and proteolytic processes. Moreover, we found members of the RXLR and CRN effector families as well as several proteins lacking an obvious signal peptide. The latter were confirmed to be bona fide extracellular proteins and this suggests that, similar to other organisms, oomycetes exploit non-conventional secretion mechanisms to transfer certain proteins to the extracellular environment.
authors.affiliation: From the ‡Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands;
authors.forename: Harold J G
authors.initials: HJ
authors.lastname: Meijer
authors.affiliation: §Proteomics Unit, Center of Genomics Regulation (CRG), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain; ¶Proteomics Unit, Universitat Pompeu Fabra (UPF), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain;
authors.forename: Francesco M
authors.initials: FM
authors.lastname: Mancuso
authors.affiliation: §Proteomics Unit, Center of Genomics Regulation (CRG), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain; ¶Proteomics Unit, Universitat Pompeu Fabra (UPF), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain;
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Espadas
authors.affiliation: From the ‡Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; ‖Centre for BioSystems Genomics, Droevendaalsesteeg, 16708 PB Wageningen, The Netherlands.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Seidl
authors.affiliation: §Proteomics Unit, Center of Genomics Regulation (CRG), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain; ¶Proteomics Unit, Universitat Pompeu Fabra (UPF), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain;
authors.forename: Cristina
authors.initials: C
authors.lastname: Chiva
authors.affiliation: From the ‡Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; ‖Centre for BioSystems Genomics, Droevendaalsesteeg, 16708 PB Wageningen, The Netherlands.
authors.forename: Francine
authors.initials: F
authors.lastname: Govers
authors.affiliation: §Proteomics Unit, Center of Genomics Regulation (CRG), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain; ¶Proteomics Unit, Universitat Pompeu Fabra (UPF), Carrer Dr. Aiguader 88, 08003 Barcelona, Spain; eduard.sabido@crg.cat.
authors.forename: Eduard
authors.initials: E
authors.lastname: Sabidó
mesh_terms: D002473:Cell Wall / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D030562:Databases, Protein; D013058:Mass Spectrometry; D010766:Phosphorylation; D055750:Phytophthora infestans / Q000737:chemistry / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D015800:Protozoan Proteins / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D003470:Culture Media; D015800:Protozoan Proteins