title: Rust secreted protein Ps87 is conserved in diverse fungal pathogens and contains a RXLR-like motif sufficient for translocation into plant cells.
abstract: BACKGROUND
  Effector proteins of biotrophic plant pathogenic fungi and oomycetes are delivered into host cells and play important roles in both disease development and disease resistance response. How obligate fungal pathogen effectors enter host cells is poorly understood. The Ps87 gene of Puccinia striiformis encodes a protein that is conserved in diverse fungal pathogens. Ps87 homologs from a clade containing rust fungi are predicted to be secreted. The aim of this study is to test whether Ps87 may act as an effector during Puccinia striiformis infection.
  
  
  RESULTS
  Yeast signal sequence trap assay showed that the rust protein Ps87 could be secreted from yeast cells, but a homolog from Magnaporthe oryzae that was not predicted to be secreted, could not. Cell re-entry and protein uptake assays showed that a region of Ps87 containing a conserved RXLR-like motif [K/R]RLTG was confirmed to be capable of delivering oomycete effector Avr1b into soybean leaf cells and carrying GFP into soybean root cells. Mutations in the Ps87 motif (KRLTG) abolished the protein translocation ability.
  
  
  CONCLUSIONS
  The results suggest that Ps87 and its secreted homologs could utilize similar protein translocation machinery as those of oomycete and other fungal pathogens. Ps87 did not show direct suppression activity on plant defense responses. These results suggest Ps87 may represent an "emerging effector" that has recently acquired the ability to enter plant cells but has not yet acquired the ability to alter host physiology.
authors.affiliation: College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Gu
authors.forename: Shiv D
authors.initials: SD
authors.lastname: Kale
authors.forename: Qinhu
authors.initials: Q
authors.lastname: Wang
authors.forename: Dinghe
authors.initials: D
authors.lastname: Wang
authors.forename: Qiaona
authors.initials: Q
authors.lastname: Pan
authors.forename: Hua
authors.initials: H
authors.lastname: Cao
authors.forename: Yuling
authors.initials: Y
authors.lastname: Meng
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Kang
authors.forename: Brett M
authors.initials: BM
authors.lastname: Tyler
authors.forename: Weixing
authors.initials: W
authors.lastname: Shan
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001487:Basidiomycota / Q000276:immunology*; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D009868:Oomycetes / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D010641:Phenotype; D010802:Phylogeny; D059828:Plant Cells / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D057865:Plant Immunity / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D021382:Protein Sorting Signals; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000382:microbiology*; D014774:Virulence
chemical_list: D005656:Fungal Proteins; D021382:Protein Sorting Signals
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