Assuntos
Antipsicóticos/efeitos adversos , Hipotermia/induzido quimicamente , Risperidona/efeitos adversos , Adulto , Transtornos da Consciência/induzido quimicamente , Transtornos da Consciência/diagnóstico , Substituição de Medicamentos , Feminino , Haloperidol/uso terapêutico , Humanos , Hipotermia/diagnóstico , Síndrome do QT Longo/induzido quimicamente , Síndrome do QT Longo/diagnósticoRESUMO
In Escherichia coli the transcription of the lactose operon, like other catabolite-sensitive operons, requires catabolite gene activator protein and 3',5'-cyclic adenosine monophosphate in addition to ribonucleic acid polymerase. We isolated and analyzed lac(+) revertants from a crp(-) strain of E. coli. We found that revertants with a higher level of expression only for the lac operon lie in the lac promoter region. These promoter mutations have no effect on operator or repressor function. Two of the revertants in which the lesions have been more precisely mapped carry mutations in the operator proximal segment of the promoter.
Assuntos
AMP Cíclico/metabolismo , Escherichia coli/metabolismo , Lactose/metabolismo , Mutação , Óperon , Proteínas de Bactérias/metabolismo , Mapeamento Cromossômico , RNA Polimerases Dirigidas por DNA/biossíntese , Escherichia coli/enzimologia , Escherichia coli/isolamento & purificação , Galactosidases/metabolismo , Genes , Mutagênicos , Purinas , Recombinação Genética , Transcrição GênicaRESUMO
Lambdoid phages form clear plaques and show reduced ability to establish immunity in strains of Escherichia coli that lack adenylate cyclase or catabolite activator protein. The absence of the activator protein or cyclic AMP reduces the frequency of lysogenization, but does not prevent steady-state repressor synthesis of a lysogen. Lambda phage mutants able to form turbid plaques on strains that lack catabolite activator protein or adenylate cyclase have been isolated and analyzed.
Assuntos
Adenilil Ciclases/metabolismo , Proteínas de Bactérias/metabolismo , Colífagos/patogenicidade , Escherichia coli/metabolismo , Cruzamentos Genéticos , Meios de Cultura , AMP Cíclico/metabolismo , Escherichia coli/enzimologia , Genótipo , Hibridização Genética , Lisogenia , MutaçãoRESUMO
An assay system for the in vitro transcription of the lac operon is described. A protein factor (CAP) and cyclic AMP, which are essential for the lac expression in vivo, also stimulate lac transcription in vitro.
Assuntos
Nucleotídeos de Adenina/metabolismo , Proteínas de Bactérias/metabolismo , Colífagos/metabolismo , DNA Viral/metabolismo , Código Genético , Lactose/metabolismo , RNA Viral/metabolismo , AMP Cíclico/metabolismo , Genes Reguladores , Hibridização Genética , Técnicas In Vitro , Mutação , Óperon , RNA Nucleotidiltransferases/metabolismo , Moldes GenéticosRESUMO
The maximum rate of expression of the lac operon is severely reduced in lac promoter mutants. Revertants of these mutations which produce higher levels of enzyme were isolated. Some of these revertants had lost sensitivity to catabolite repression and transient repression. The mutations responsible for these losses took place at sites very close to the original promoter mutations. From these results we conclude that the promoter itself is the target site for both catabolite and transient repression of the lac operon.
