RESUMO
The oligopeptide permease (Opp) cassette, an oligopeptide transport system belongs to the superfamily of ATP-binding cassette (ABC) transporter, is widely distributed in bacteria, including Streptococcus suis (S. suis). It is encoded by the opp operon containing oppA, oppB, oppC, oppD, and oppF. In addition to the uptake of peptide, the oppA gene also plays an important role in virulence of many pathogens. In this study, an oppA homologue from the highly virulent S. suis serotype 2 (S. suis 2) strain 05ZYH33 was identified. Flow cytometry and Western blot confirmed that OppA is a surface immunogenic protein and is expressed during S. suis 2 infection. To explore the role of oppA in S. suis 2 growth and pathogenicity, an isogenic 05ZYH33 mutant of oppA (â³oppA) was obtained by homologous recombination. Although the complementary strain was not obtained due to the â³oppA strain is not transformable, the current data revealed that deletion of the oppA gene in S. suis 2 has greatly affected its growth and virulence. Our data revealed that the growth rate is significantly slow for the â³oppA. Adherence of the â³oppA strain to human epithelial cells is greatly reduced comparing to the wild strain. Mouse infection experiment showed that inactivation of oppA greatly attenuated the high pathogenicity of S. suis 2. The observed results suggest that OppA is a surface-exposed protein and plays important roles in the growth and pathogenicity of S. suis 2.
Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Proteínas de Transporte/genética , Proteínas de Transporte/fisiologia , Lipoproteínas/genética , Lipoproteínas/fisiologia , Streptococcus suis/genética , Streptococcus suis/metabolismo , Fatores de Virulência/genética , Fatores de Virulência/fisiologia , Sequência de Aminoácidos , Animais , Antígenos de Superfície/genética , Antígenos de Superfície/imunologia , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Proteínas de Transporte/isolamento & purificação , Células Epiteliais/microbiologia , Feminino , Regulação Bacteriana da Expressão Gênica , Recombinação Homóloga , Humanos , Lipoproteínas/isolamento & purificação , Proteínas de Membrana/genética , Proteínas de Membrana/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Óperon , Alinhamento de Sequência , Infecções Estreptocócicas/genética , Streptococcus suis/crescimento & desenvolvimento , Streptococcus suis/patogenicidade , Fatores de Virulência/isolamento & purificaçãoRESUMO
Streptococcus suis serotype 2 is an important swine pathogen and an emerging zoonotic agent that causes severe infections. Recent studies have reported a eukaryotic-like Ser/Thr protein kinase (STK) gene and characterized its role in the growth and virulence of different S. suis 2 strains. In the present study, phosphoproteomic analysis was adopted to identify substrates of the STK protein. Seven proteins that were annotated to participate in different cell processes were identified as potential substrates, which suggests the pleiotropic effects of stk on S. suis 2 by targeting multiple pathways. Among them, a protein characterized as cell division initiation protein (DivIVA) was further investigated. In vitro analysis demonstrated that the recombinant STK protein directly phosphorylates threonine at amino acid position 199 (Thr-199) of DivIVA. This effect could be completely abolished by the T199A mutation. To determine the specific role of DivIVA in growth and division, a divIVA mutant was constructed. The ΔdivIVA strain exhibited impaired growth and division, including lower viability, enlarged cell mass, asymmetrical division caused by aberrant septum, and extremely weak pathogenicity in a mouse infection model. Collectively, our results reveal that STK regulates the cell growth and virulence of S. suis 2 by targeting substrates that are involved in different biological pathways. The inactivation of DivIVA leads to severe defects in cell division and strongly attenuates pathogenicity, thereby indicating its potential as a molecular drug target against S. suis.
