RESUMO
"Cluster 9" family lipoproteins function as ligand-binding subunits of ABC-type transporters in maintaining transition metal homeostasis and have been implicated in the virulence of several bacteria. While these proteins share high similarity, the specific metal that they recognize and whether their role in virulence directly involves metal homeostasis cannot be reliably predicted. We examined the cluster 9 protein Lsp of Streptococcus pyogenes and found that specific deletion of lsp produced mutants highly attenuated in a murine model of soft tissue infection. Under standard in vitro conditions, growth of the Lsp(-) mutant was indistinguishable from that of the wild type, but growth was defective under zinc-limited conditions. The growth defect could be complemented by plasmids expressing wild-type Lsp but not Lsp engineered to lack its putative lipidation residue. Furthermore, Zn(2+) but not Mn(2+) rescued Lsp(-) growth, implicating Zn(2+) as the physiological ligand for Lsp. Mutation of residues in the putative Zn(2+)-binding pocket generated variants both hypo- and hyper-resistant to zinc starvation, and both mutant classes displayed attenuated virulence. Together, these data suggest that Lsp is a ligand-binding component of an ABC-type zinc permease and that perturbation of zinc homeostasis inhibits the ability of S. pyogenes to cause disease in a zinc-limited host milieu.
Assuntos
Transportadores de Cassetes de Ligação de ATP/fisiologia , Streptococcus pyogenes/metabolismo , Streptococcus pyogenes/patogenicidade , Fatores de Virulência/fisiologia , Zinco/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Sítios de Ligação , Deleção de Genes , Teste de Complementação Genética , Manganês/metabolismo , Camundongos , Mutagênese Sítio-Dirigida , Mutação de Sentido Incorreto , Infecções dos Tecidos Moles/microbiologia , Infecções dos Tecidos Moles/patologia , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/patologia , Streptococcus pyogenes/crescimento & desenvolvimento , Virulência , Fatores de Virulência/genéticaAssuntos
Abscesso Abdominal/diagnóstico , Abscesso Abdominal/tratamento farmacológico , Doença de Crohn/diagnóstico , Doença de Crohn/tratamento farmacológico , Fístula/diagnóstico , Fístula/tratamento farmacológico , Abscesso Abdominal/etiologia , Abscesso Abdominal/patologia , Criança , Doença de Crohn/complicações , Doença de Crohn/patologia , Fístula/etiologia , Fístula/patologia , Humanos , Relatório de PesquisaRESUMO
In Streptococcus pyogenes, mutation of the peroxide sensor PerR results in avirulence despite producing hyper-resistance to peroxide stress. To understand the basis of this effect, global transcription profiling was conducted revealing one highly downregulated gene (czcD), and five highly upregulated genes in the mutant. Of the latter, only pmtA contained a binding site for PerR, while phtY, phtD, lsp and rpsN2 harboured an AdcR motif and were regulated by AdcR, a repressor of an ABC-type metal transporter. Furthermore, only the PerR-regulated pmtA (PerR-regulated metal transporter A), a putative metal transporter, contributed to resistance against peroxide stress, while AdcR and the other AdcR-regulated genes did not. However, overexpression of pmtA resulted in upregulation of several AdcR-regulated genes, suggesting that the AdcR regulon is sensitive to PerR regulation of metal homeostasis. Finally, examination of S. pyogenes following murine subcutaneous infection revealed that while pmtA was not upregulated in a late infection, the AdcR-regulated genes were. Taken together, these data suggest that PerR has a greater impact on the transcriptome than can be predicted by its binding sites and that pmtA functions to link metal homeostasis and oxidative stress responses.