RESUMO
Genes rcsC and rcsB form a two-component system in which rcsC encodes the sensor element and rcsB the regulator. In Escherichia coli, the system positively regulates the expression of the capsule operon, cps, and of the cell division gene ftsZ. We report the identification of the promoter and of the sequences required for rcsB-dependent stimulation of ftsZ expression. The promoter, ftsA1p, located in the ftsQ coding sequence, co-regulates ftsA and ftsZ. The sequences required for rcsB activity are immediately adjacent to this promoter.
Assuntos
Proteínas de Bactérias/genética , Proteínas do Citoesqueleto , Proteínas de Escherichia coli , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Complexos Multienzimáticos , Fosfoproteínas Fosfatases , Proteínas Quinases , Proteínas de Bactérias/metabolismo , Sequência de Bases , Divisão Celular/genética , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/metabolismo , Deleção de Genes , Genes Bacterianos , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição GênicaRESUMO
Several proteins that may regulate c-myc mRNA post-transcriptionally were previously isolated and characterized. Two of them, HuR and AUF1, bind specifically to the 3' untranslated region (UTR) of c-myc mRNA. Because c-myc is regulated post-transcriptionally in various mouse tissues, including quiescent tissues, fetal liver and regenerating liver, we investigated whether HuR and AUF1 expression was also regulated in these tissues. Concerning AUF1, we analysed the expression of various mRNA and protein isoforms. We discovered a new AUF1 mRNA variant with a long AU-rich 3' UTR. We show that AUF1 expression, regardless of the RNA isoform considered, and HuR mRNA expression parallel c-myc expression in quiescent tissues and during liver development; their expression is high in lymphoid tissues and fetal liver and low in adult liver. However, no upregulation of HuR or AUF1 accompanies the upregulation of c-myc mRNA following partial hepatectomy. We discuss our results in relation to the current hypothesis that HuR and AUF1 act as mRNA destabilizing factors.
