title: Pro-apoptotic effect of a Mycoplasma hyopneumoniae putative type I signal peptidase on PK(15) swine cells.
abstract: Mycoplasma hyopneumoniae is an economically significant swine pathogen that causes porcine enzootic pneumonia (PEP). Important processes for swine infection by M. hyopneumoniae depend on cell surface proteins, many of which are secreted by secretion pathways not completely elucidated so far. A putative type I signal peptidase (SPase I), a possible component of a putative Sec-dependent pathway, was annotated as a product of the sipS gene in the pathogenic M. hyopneumoniae 7448 genome. This M. hyopneumoniae putative SPase I (MhSPase I) displays only 14% and 23% of sequence identity/similarity to Escherichia coli bona fide SPase I, and, in complementation assays performed with a conditional E. coli SPase I mutant, only a partial restoration of growth was achieved with the heterologous expression of a recombinant MhSPase I (rMhSPase I). Considering the putative surface location of MhSPase I and its previously demonstrated capacity to induce a strong humoral response, we then assessed its potential to elicit a cellular and possible immunomodulatory response. In assays for immunogenicity assessment, rMhSPase I unexpectedly showed a cytotoxic effect on murine splenocytes. This cytotoxic effect was further confirmed using the swine epithelial PK(15) cell line in MTT and annexin V-flow cytometry assays, which showed that rMhSPase I induces apoptosis in a dose dependent-way. It was also demonstrated that this pro-apoptotic effect of rMhSPase I involves activation of a caspase-3 cascade. The potential relevance of the rMhSPase I pro-apoptotic effect for M. hyopneumoniae-host interactions in the context of PEP is discussed.
authors.affiliation: Laboratório de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
authors.forename: Jéssica A
authors.initials: JA
authors.lastname: Paes
authors.affiliation: Laboratório de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
authors.forename: Veridiana G
authors.initials: VG
authors.lastname: Virginio
authors.affiliation: Laboratório de Biologia Molecular de Cestódeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
authors.forename: Martín
authors.initials: M
authors.lastname: Cancela
authors.affiliation: Laboratório de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
authors.forename: Fernanda M A
authors.initials: FMA
authors.lastname: Leal
authors.affiliation: Laboratório de Imunologia Celular, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Brazil.
authors.forename: Thiago J
authors.initials: TJ
authors.lastname: Borges
authors.affiliation: Laboratório de Imunologia Celular, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Brazil.
authors.forename: Natália
authors.initials: N
authors.lastname: Jaeger
authors.affiliation: Laboratório de Imunologia Celular, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Brazil.
authors.forename: Cristina
authors.initials: C
authors.lastname: Bonorino
authors.affiliation: Laboratório de Microrganismos Diazotróficos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
authors.forename: Irene S
authors.initials: IS
authors.lastname: Schrank
authors.affiliation: Laboratório de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil. Electronic address: henrique@cbiot.ufrgs.br.
authors.forename: Henrique B
authors.initials: HB
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D017209:Apoptosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D045705:Mycoplasma hyopneumoniae / Q000201:enzymology* / Q000235:genetics; D045729:Pneumonia of Swine, Mycoplasmal / Q000382:microbiology*; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D013552:Swine; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D037521:Virulence Factors; D012697:Serine Endopeptidases; C026515:type I signal peptidase; D053148:Caspase 3
keywords: Apoptosis; Cytotoxicity; M. hyopneumoniae sipS; Porcine enzootic pneumonia; SPase I; Virulence factor