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Category: Microbial Genetics and Molecular Biology; Bacterial Pathogenesis
Yops of the Pathogenic Yersinia spp., Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818340/9781555810825_Chap24-1.gif /docserver/preview/fulltext/10.1128/9781555818340/9781555810825_Chap24-2.gifAbstract:
During their interaction with host cells, the pathogenic Yersinia spp. export a set of proteins known as the Yersinia outer membrane proteins, or Yops. This chapter reviews the work that led to the discovery of the Yops and discusses recent progress made in understanding the expression and function of these proteins. Bacterial infection of the lungs results in pneumonic plague, a form of the disease that is transmissible by aerosolization and that is often fatal. Yersinia enterocolitica is responsible for a variety of human illnesses ranging in severity from mild gastroenteritis to acute terminal ileitis. Various rodents, farm animals, and birds are the normal reservoirs for Y. pseudotuberculosis. The product of yscC shares significant homology with PulD, a protein required for the export of pullulanase by Klebsiella pneumoniae. A number of additional polypeptides (later to be identified as the Yops) were detected in sucrose gradient-purified outer membranes from pYV-containing Y. enterocolitica and Yersinia pseudotuberculosis grown under LCR conditions. The ability of Yersinia strains to induce rounding and detachment of cultured mammalian cells has been referred to as "cytotoxicity". A partial cytotoxic activity is reconstituted if these protein preparations are introduced into HeLa cells by the use of glass carrier beads. This indicates that YopE must enter the cytoplasm of the host cell to be active. Signal transduction is critically involved in a number of cellular host responses to microbial infection.
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SDS-PAGE analysis of Y. enterocolitica outer membrane polypeptides. Lane A, strain 9576 grown at 25°C; lane B, strain 9576-c grown at 25°C; lane C, strain 9576 grown at 37°C; lane D, strain 9576-c grown at 37°C. From Portnoy et al. ( 45 ).
SDS-PAGE analysis of Y. enterocolitica outer membrane polypeptides. Lane A, strain 9576 grown at 25°C; lane B, strain 9576-c grown at 25°C; lane C, strain 9576 grown at 37°C; lane D, strain 9576-c grown at 37°C. From Portnoy et al. ( 45 ).
Y. pseudotuberculosis inv strains harboring the virulence plasmid and pregrown at 28°C are localized intracellular in HEp-2 cells. Bacterial strains were grown at 28°C in L broth overnight and were added to monolayers of HEp-2 cells at 37°C. After 2 h for binding and entry, unbound bacteria were washed away and the monolayers were fixed, embedded, and sectioned for electron microscopy. (A and B) Virulence plasmid-cured Y. pseudotuberculosis inv. (C and D) Virulence plasmid-containing Y. pseudotuberculosis inv. From Isberg ( 33 ).
Y. pseudotuberculosis inv strains harboring the virulence plasmid and pregrown at 28°C are localized intracellular in HEp-2 cells. Bacterial strains were grown at 28°C in L broth overnight and were added to monolayers of HEp-2 cells at 37°C. After 2 h for binding and entry, unbound bacteria were washed away and the monolayers were fixed, embedded, and sectioned for electron microscopy. (A and B) Virulence plasmid-cured Y. pseudotuberculosis inv. (C and D) Virulence plasmid-containing Y. pseudotuberculosis inv. From Isberg ( 33 ).
Y. pseudotuberculosis inv strains harboring the virulence plasmid and pregrown at 37°C do not enter HEp-2 cells. Y. pseudotuberculosis inv was grown overnight in L broth at 28°C. Freshly saturated cultures were diluted in the same medium and were aerated at 37°C for 3 h at this temperature before addition to monolayers of HEp-2 cells. After 2 h for binding and intracellular entry of the bacteria, the monolayers were washed and processed for thin-section electron microscopy. Displayed are two micrographs of Y. pseudotuberculosis inv infected in this fashion. From Isberg ( 33 ).
Y. pseudotuberculosis inv strains harboring the virulence plasmid and pregrown at 37°C do not enter HEp-2 cells. Y. pseudotuberculosis inv was grown overnight in L broth at 28°C. Freshly saturated cultures were diluted in the same medium and were aerated at 37°C for 3 h at this temperature before addition to monolayers of HEp-2 cells. After 2 h for binding and intracellular entry of the bacteria, the monolayers were washed and processed for thin-section electron microscopy. Displayed are two micrographs of Y. pseudotuberculosis inv infected in this fashion. From Isberg ( 33 ).
SDS-PAGE analysis of proteins released by Y. pseudotuberculosis yopH mutants. Y. pseudotuberculosis strains were grown at 37°C in a defined low-Ca2+ medium ( 6 , 61 ). Proteins were isolated from the growth medium by precipitation with trichloroacetic acid and were analyzed by electrophoresis on an SDS-polyacrylamide gel (12%). The strains used are described in Bliska et al. ( 4 ). Lane 1, plasmid-cured Y. pseudotuberculosis; lane 2, wild-type Y. pseudotuberculosis (yopH + ); lane 3, Y. pseudotuberculosis catalytic YopH mutant (yopHC403A); lane 4, Y. pseudotuberculosis YopH deletion mutant (yopHΔ). The positions of the molecular size markers (in kilodaltons) and YopH are indicated on the right.
SDS-PAGE analysis of proteins released by Y. pseudotuberculosis yopH mutants. Y. pseudotuberculosis strains were grown at 37°C in a defined low-Ca2+ medium ( 6 , 61 ). Proteins were isolated from the growth medium by precipitation with trichloroacetic acid and were analyzed by electrophoresis on an SDS-polyacrylamide gel (12%). The strains used are described in Bliska et al. ( 4 ). Lane 1, plasmid-cured Y. pseudotuberculosis; lane 2, wild-type Y. pseudotuberculosis (yopH + ); lane 3, Y. pseudotuberculosis catalytic YopH mutant (yopHC403A); lane 4, Y. pseudotuberculosis YopH deletion mutant (yopHΔ). The positions of the molecular size markers (in kilodaltons) and YopH are indicated on the right.
Structure of YopH. At the top is shown a restriction map of yopH and a corresponding scale in kilobases. At the bottom is shown a functional map of YopH with a scale corresponding to length in amino acids. The domains involved in various functions of the protein are indicated. Sec, N-terminal 48 residues sufficient for export ( 41 ); YscM, region of YopH that is homologous to YscM (LcrQ) and that corresponds to the first 128 amino acids and overlaps the export domain ( 42 , 52 ): SRD; substrate recognition domain (residues 129 to 261), a region of the protein involved in phosphoprotein-binding activity ( 2 , 4 ); PTPase, domain of YopH that is homologous to eukaryotic protein tyrosine phosphatase catalytic domains ( 26 ).
Structure of YopH. At the top is shown a restriction map of yopH and a corresponding scale in kilobases. At the bottom is shown a functional map of YopH with a scale corresponding to length in amino acids. The domains involved in various functions of the protein are indicated. Sec, N-terminal 48 residues sufficient for export ( 41 ); YscM, region of YopH that is homologous to YscM (LcrQ) and that corresponds to the first 128 amino acids and overlaps the export domain ( 42 , 52 ): SRD; substrate recognition domain (residues 129 to 261), a region of the protein involved in phosphoprotein-binding activity ( 2 , 4 ); PTPase, domain of YopH that is homologous to eukaryotic protein tyrosine phosphatase catalytic domains ( 26 ).
Yops and other pYV-encoded proteins released by yersiniae
a The names and apparent molecular masses of the proteins released from Yersinia spp. are given. Molecular masses are from Michiels et al. ( 43 ).
b Number of amino acids in each protein as predicted from the gene sequence. Values are for proteins encoded by Y. pseudotuberculosis unless indicated otherwise by the abbreviations in parentheses: Ype, Y. pestis; Ye, Y. enterocolitica.
c ND, not determined.
Yops and other pYV-encoded proteins released by yersiniae
a The names and apparent molecular masses of the proteins released from Yersinia spp. are given. Molecular masses are from Michiels et al. ( 43 ).
b Number of amino acids in each protein as predicted from the gene sequence. Values are for proteins encoded by Y. pseudotuberculosis unless indicated otherwise by the abbreviations in parentheses: Ype, Y. pestis; Ye, Y. enterocolitica.
c ND, not determined.