AnÃlise da regulaÃÃo transcricional de genes de Yersinia em Escherichia coli

AUTOR(ES)

PatrÃcia Rodrigues de Oliveira Haver

DATA DE PUBLICAÇÃO

2005

RESUMO

Yersiniae possess a type III secretion system, responsible for the translocation of proteins known as Yops, to the interior of the eukaryotic cells of the host. The YopH protein is a tyrosine phosphatase that desphosphorylates signalling molecules and impairs phagocytosis in macrophages. For its efficient secretion it needs the presence of the chaperone SycH that allows its recognition by the secretion machinery. With the purpose to analyse the expression of the YopH protein, a hybrid promoter was constructed with the lac promoter of Escherichia coli followed by the yopH promoter of Yersinia enterocolitica. This promoter was capable to direct a strong expression of the YopH in E. coli, and an optimal synthesis of YopH was observed with increase in temperature (37ÂC) and in cultures in growth phase. The expression of the YopH was investigated in E. coli strains defective in proteins homologous to the histones, Hha and H-NS. The expression was significantly higher at 24ÂC than to 37ÂC, in the absence of H-NS, but not Hha. These results are compatible with the role of the H-NS in the regulation of the activity of the promoter yoph, possibly through the presence of curves in its structure. To determine if the presence of the chaperone SycH would influence the expression of the YopH, in E. coli, the sequence coding for this protein was amplified and cloned in the plasmid pBAD33. The expression of SycH was observed in cultures of E. coli, only in presence of arabinose. The co-expression of the proteins YopH e SycH, in EPEC, resulted in reduction of the expression of the YopH, in presence of arabinose. The same was observed in EPEC cultures with only the plasmid pTZ/YopH, and concentration of arabinose and glucose would be acting in the expression of the YopH. To evaluate the potential of the YopH protein in the diagnosis of plague, several sera from plague suspect patients and rabbits immunized with Y. pestis strains had been tested by Western-blot. The tested sera did not recognize YopH

ASSUNTO(S)

yoph yersinia h-ns f1 yoph diagnÃstico f1 ciencias biologicas yersinia sych h-ns sych diagnostic

Documentos Relacionados

• HeurÃstica de RegulaÃÃo CombinatÃria na ReconstruÃÃo de Redes de Genes
• A TributaÃÃo como instrumento de regulaÃÃo econÃmico em PaÃses integrados
• Tribunais de Contas e a regulaÃÃo do transporte intermunicipal de passageiros por Ãnibus (TIPO)
• O elo corporativo? grupos de interesse, financiamento de campanha e regulaÃÃo eleitoral
• RegulaÃÃo e eficiÃncia no mercado de capitais: a informaÃÃo como alvo central da atuaÃÃo regulatÃria da CVM