title: Translocation of YopE and YopN into eukaryotic cells by Yersinia pestis yopN, tyeA, sycN, yscB and lcrG deletion mutants measured using a phosphorylatable peptide tag and phosphospecific antibodies.
abstract: Yersinia pestis, the causative agent of plague, exports a set of virulence proteins called Yops upon contact with eukaryotic cells. A subset of these Yops is translocated directly into the cytosol of host cells. In this study, a novel protein tag-based reporter system is used to measure the translocation of Yops into cultured eukaryotic cells. The reporter system uses a small bipartite phosphorylatable peptide tag, termed the Elk tag. Translocation of an Elk-tagged protein into eukaryotic cells results in host cell protein kinase-dependent phosphorylation of the tag at a specific serine residue, which can subsequently be detected with phosphospecific antibodies. The YopN, TyeA, SycN, YscB and LcrG proteins function to prevent Yop secretion before host cell contact. The role of these proteins was investigated in the translocation of Elk-tagged YopE (YopE129-Elk) and YopN (YopN293-Elk) into HeLa cells. Y. pestis yopN, tyeA, sycN and yscB deletion mutants showed reduced levels of YopE129-Elk phosphorylation compared with the parent strain, indicating that these mutants translocate reduced amounts of YopE. We also demonstrate that YopN293-Elk is translocated into HeLa cells and that this process is more efficient in a Yersinia yop polymutant strain lacking the six translocated effector Yops. Y. pestis sycN and yscB mutants translocated reduced amounts of YopN293-Elk; however, tyeA and lcrG mutants translocated higher amounts of YopN293-Elk compared with the parent strain. These data suggest that TyeA and LcrG function to suppress the secretion of YopN before host cell contact, whereas SycN and YscB facilitate YopN secretion and subsequent translocation.
authors.affiliation: Department of Microbiology and Immunology, University of Miami School of Medicine, Miami, FL 33101, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: Day
authors.forename: Franco
authors.initials: F
authors.lastname: Ferracci
authors.forename: Gregory V
authors.initials: GV
authors.lastname: Plano
mesh_terms: D000906:Antibodies / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics; D005057:Eukaryotic Cells / Q000382:microbiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones / Q000235:genetics; D019913:Nuclear Localization Signals / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D052899:Pore Forming Cytotoxic Proteins; D013539:Simian virus 40; D014157:Transcription Factors / Q000737:chemistry; D014774:Virulence; D015010:Yersinia pestis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*
chemical_list: D000906:Antibodies; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C088009:LcrG protein, Yersinia; D008565:Membrane Proteins; D018832:Molecular Chaperones; D019913:Nuclear Localization Signals; D010455:Peptides; D052899:Pore Forming Cytotoxic Proteins; C117910:SycN protein, Yersinia enterocolitica; D014157:Transcription Factors; C112196:TyeA protein, Yersinia; C117911:YscB protein, Yersinia pestis; C063239:yopE protein, Yersinia; C070015:YopN protein, Yersinia