RESUMO
In this study, we combined metabolic reconstruction, growth assays, and metabolome and transcriptome analyses to obtain a global view of the sulfur metabolic network and of the response to sulfur availability in Brevibacterium aurantiacum. In agreement with the growth of B. aurantiacum in the presence of sulfate and cystine, the metabolic reconstruction showed the presence of a sulfate assimilation pathway, thiolation pathways that produce cysteine (cysE and cysK) or homocysteine (metX and metY) from sulfide, at least one gene of the transsulfuration pathway (aecD), and genes encoding three MetE-type methionine synthases. We also compared the expression profiles of B. aurantiacum ATCC 9175 during sulfur starvation or in the presence of sulfate. Under sulfur starvation, 690 genes, including 21 genes involved in sulfur metabolism and 29 genes encoding amino acids and peptide transporters, were differentially expressed. We also investigated changes in pools of sulfur-containing metabolites and in expression profiles after growth in the presence of sulfate, cystine, or methionine plus cystine. The expression of genes involved in sulfate assimilation and cysteine synthesis was repressed in the presence of cystine, whereas the expression of metX, metY, metE1, metE2, and BL613, encoding a probable cystathionine-γ-synthase, decreased in the presence of methionine. We identified three ABC transporters: two operons encoding transporters were transcribed more strongly during cysteine limitation, and one was transcribed more strongly during methionine depletion. Finally, the expression of genes encoding a methionine γ-lyase (BL929) and a methionine transporter (metPS) was induced in the presence of methionine in conjunction with a significant increase in volatile sulfur compound production.
Assuntos
Brevibacterium , Regulação Bacteriana da Expressão Gênica , Enxofre/metabolismo , Brevibacterium/enzimologia , Brevibacterium/genética , Brevibacterium/crescimento & desenvolvimento , Brevibacterium/metabolismo , Carbono-Oxigênio Liases/genética , Carbono-Oxigênio Liases/metabolismo , Liases de Carbono-Enxofre/genética , Liases de Carbono-Enxofre/metabolismo , Cisteína/biossíntese , Cisteína/metabolismo , Cistina/metabolismo , Perfilação da Expressão Gênica , Homocisteína/biossíntese , Metaboloma , Metionina/biossíntese , Metionina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Multilocus sequence typing with nine selected genes is shown to be a promising new tool for accurate identifications of Brevibacteriaceae at the species level. A developed microarray also allows intraspecific diversity investigations of Brevibacterium aurantiacum showing that 13% to 15% of the genes of strain ATCC 9174 were absent or divergent in strain BL2 or ATCC 9175.
Assuntos
Técnicas de Tipagem Bacteriana/métodos , Brevibacterium/classificação , Brevibacterium/isolamento & purificação , Hibridização Genômica Comparativa/métodos , Impressões Digitais de DNA/métodos , Análise de Sequência de DNA/métodos , Sequência de Bases , Brevibacterium/genética , Análise por Conglomerados , Variação Genética , Genótipo , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Filogenia , Alinhamento de SequênciaRESUMO
Group B streptococcus (GBS) expresses a hemolysin/cytolysin that plays an important role in pathogenesis. Using the Himar1 transposon mutagenesis system, a hypohemolytic mutant carrying an interrupted cylJ gene was characterized. cylJ, encoding a putative glycosyltransferase, and cylK, whose product is unknown, are both required for the full hemolytic/cytolytic activity, pigment formation, and virulence of GBS.