RESUMO
Ectoderm and mesoderm can be considered as prototypes for epithelial and mesenchymal cell types. These two embryonic tissues display clear differences in adhesive and motility properties, which are phenomenologically well characterized but remain largely unexplored at the molecular level. Because the key downstream regulations must occur at the plasma membrane and in the underlying actin cortical structures, we have set out to compare the protein content of membrane fractions from Xenopus ectoderm and mesoderm tissues using 2-dimensional difference gel electrophoresis (DiGE). We have thus identified several proteins that are enriched in one or the other tissues, including regulators of the cytoskeleton and of cell signaling. This study represents to our knowledge the first attempt to use proteomics specifically targeted to the membrane-cortex compartment of embryonic tissues. The identified components should help unraveling a variety of tissue-specific functions in the embryo.
Assuntos
Ectoderma/química , Mesoderma/química , Proteínas/análise , Proteômica/métodos , Eletroforese em Gel Diferencial Bidimensional/métodos , Análise de Variância , Animais , Ectoderma/embriologia , Imuno-Histoquímica , Espaço Intracelular , Mesoderma/embriologia , Especificidade de Órgãos , Análise de Componente Principal , Proteínas/química , Proteínas/classificação , Proteoma/análise , Proteoma/química , XenopusRESUMO
Actinobacillus pleuropneumoniae, a bacterial pathogen of swine and agent of porcine pneumonia, causes a highly infectious disease of economic importance in the pig industry. Commercial vaccines for A. pleuropneumoniae include whole-cell bacterins and second generation subunit vaccines but they only confer partial protective immunity. Our search for new vaccine candidates identified antigens that are expressed during conditions that mimic infection; the outer membrane (OM) proteome of A. pleuropneumoniae serotype 5b was examined under iron restriction. Quantitative profiling by 2D-DiGE technology revealed that iron restriction induced expression of previously described transferrin binding proteins (TbpA, TbpB) plus four lipoproteins including spermidine/putrescine binding periplasmic protein 1 precursor (PotD2). Immunoproteomic analyses with antisera from naïve animals and from infected pigs were able to differentiate antigens within the OM proteome that were specifically recognized during A. pleuropneumoniae infection. Immunoblots of iron-restricted profiles detected PotD2, heme-binding protein A (HbpA), and capsule polysaccharide export protein (CpxD) as well as surface antigens TbpA, TbpB, and OmlA. These data identify OM proteins that demonstrate immunogenicity and upregulation under conditions mimicking infection, providing emphasis on lipoproteins as an important class of antigens to exploit for vaccine development for A. pleuropneumoniae.
Assuntos
Actinobacillus pleuropneumoniae/crescimento & desenvolvimento , Actinobacillus pleuropneumoniae/metabolismo , Antígenos de Bactérias/análise , Proteínas da Membrana Bacteriana Externa/metabolismo , Ferro/metabolismo , Proteoma , Animais , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Ferro/farmacologia , Eletroforese em Gel Diferencial BidimensionalRESUMO
The structural maintenance of chromosome (Smc) protein is highly conserved and involved in chromosome compaction, cohesion, and other DNA-related processes. In Bacillus subtilis, smc null mutations cause defects in DNA supercoiling, chromosome compaction, and chromosome partitioning. We investigated the effects of smc mutations on global gene expression in B. subtilis using DNA microarrays. We found that an smc null mutation caused partial induction of the SOS response, including induction of the defective prophage PBSX. Analysis of SOS and phage gene expression in single cells indicated that approximately 1% of smc mutants have fully induced SOS and PBSX gene expression while the other 99% of cells appear to have little or no expression. We found that induction of PBSX was not responsible for the chromosome partitioning or compaction defects of smc mutants. Similar inductions of the SOS response and PBSX were observed in cells depleted of topoisomerase I, an enzyme that relaxes negatively supercoiled DNA.
Assuntos
Bacillus subtilis/genética , Proteínas de Bactérias/genética , Proteínas de Ciclo Celular/genética , Deleção de Genes , Regulação Bacteriana da Expressão Gênica/genética , Resposta SOS em Genética , Fusão Gênica Artificial , Fagos Bacilares/genética , Proteínas de Bactérias/análise , Cromossomos Bacterianos/metabolismo , DNA Topoisomerases Tipo I/metabolismo , Perfilação da Expressão Gênica , Genes Reporter , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/genética , Proteínas Luminescentes/análise , Proteínas Luminescentes/genética , Microscopia de Fluorescência , Análise de Sequência com Séries de Oligonucleotídeos , Ativação ViralRESUMO
The Spx protein of Bacillus subtilis represses activator-stimulated transcription by interacting with the C-terminal domain of RNA polymerase (RNAP) alpha subunit. Its concentration increases in cells lacking the ATP-dependent protease, ClpXP, resulting in severe effects on growth and developmental processes. Microarray analysis was undertaken to identify genes that are induced or repressed when Spx interacts with RNAP. The induced genes included those encoding products known to function in maintaining thiol homeostasis. Two genes, thioredoxin (trxA) and thioredoxin reductase (trxB), are transcriptionally induced under conditions of thiol-specific oxidative (disulfide) stress by a mechanism involving Spx-RNAP interaction. Disulfide stress also results in an increase in Spx-dependent transcriptional repression. The increase in Spx activity in cells encountering disulfide stress is due in part to a posttranscriptional mechanism of spx control resulting in an increase in Spx concentration. An spx null mutant and a strain bearing an allele of rpoA that prevents Spx-RNAP interaction show hypersensitivity to disulfide stress. From these results, it is proposed that Spx is an activator that mobilizes the operations necessary to reverse the effects of oxidative damage, but it also serves as a negative regulator that causes the postponement of developmental programs and energy-consuming growth-related functions while the cell copes with the period of stress.