RESUMO
Mutagenesis of Streptomyces venezuelae ISP5230 and selection for P-aminobenzoic acid-dependent growth in the presence of sulfanilamide yielded pab mutants (VS519 and VS620) that continued to produce chloramphenicol (Cm), although with increased medium dependence. Transforming the mutants with pDQ102 or pDQ103, which carried a pab-complementing fragment from S. venezuelae ISP5230 in alternative orientations, restored uniformly high Cm production in VS620, but did not alter the medium dependence of Cm production in VS519. The cloned S. venezuelae DNA fragment was subcloned and trimmed to the minimum size conferring pab complementation. The resulting 2.8 kb BamHl-Sacl fragment was sequenced. Codon preference analysis showed one complete ORF encoding a polypeptide of 670 amino acids. Comparison of the deduced amino acid sequence with database proteins indicated that the N- and C-terminal regions resembled PabA and PabB, respectively, of numerous bacteria. The gene product showed overall sequence similarity to the product of a fused pabAB gene associated with secondary metabolism in Streptomyces griseus. Insertion of an apramycin resistance gene into pabAB cloned in a segregationally unstable vector and replacement of the S. venezuelae chromosomal pabAB with the disrupted copy lowered sulfanilamide resistance from 25 to 5 micrograms mL-1 and blocked Cm production.
Assuntos
Proteínas de Bactérias/fisiologia , Cloranfenicol/biossíntese , Genes Bacterianos , Streptomyces/enzimologia , Transaminases/fisiologia , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Sequência de Bases , Candicidina/biossíntese , Ácido Corísmico/metabolismo , Cromossomos Bacterianos/genética , Clonagem Molecular , Evolução Molecular , Dados de Sequência Molecular , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Streptomyces/genética , Transaminases/genética , Transformação BacterianaRESUMO
Liver glutamic-aspartic transaminase activity was investigated in 19 diabetic patients before and after treatment of the diabetic state. In 15 patients who were passing no sugar in the urine at the time of the second biopsy the mean level of transaminase activity was 0.146+- 0.013 units, whereas before treatment the activity had been 0.213+- 0.011 units. This difference is highly significant statistically. There was no apparent relation between the initial level of transaminase activity or the change in activity and the type or duration of the diabetes or of the treatment given (Summary)
Assuntos
Humanos , Adolescente , Adulto , Pessoa de Meia-Idade , Idoso , Masculino , Feminino , Fígado/metabolismo , Diabetes Mellitus/fisiopatologia , Transaminases/fisiologia , Biópsia , Gluconeogênese/fisiologia , Diabetes Mellitus/terapia , GlicemiaRESUMO
Liver glutamic-aspartic transaminase activity has been investigated in 19 diabetic subjects before and after treatment of the diabetic state. In 15 patients who were passing no sugar in the urine at the time of the second biopsy the mean level of transaminase activity was 0.146 ñ 0.013 units whereas before treatment the activity had been 0.0213 ñ 0.011 units. This difference is highly significant statistically. There was no apparent relation between the initial level of transaminase activity or the change in activity and the type or duration of the diabetes or of the treatment given (AU)