RESUMEN
ATP sulfurylase (ATPS,EC 2.7.7.4) reversibly catalyzes the reaction between ATP and sulfate to produce APS and pyrophosphate (PPi), and has been used in pyrosequencing. The gene coding ATP sulfurylase was amplified from the genomic DNA of Saccharomyces cerevisias (CICC 1202), and cloned into prokaryotic expression plasmid pET28a( + ) to provide a recombinant expression plasmid pET28a( + )-ATPS. Upon IPTG induction, ATP sulfurylase was produced by E. coli BL21 (DE3) harboring the recombinant expression plasmid pET28a( + )-ATPS. The relative molecular weight of recombinant ATP sulfurylase with His tag was about 60 kD. The recombinant ATP sulfurylase with electrophoretic pure grade was obtained only by two purification steps: His * Bind Resin affinity chromatography and ultrafiltration. The specific activity of the purified recombinant ATP sulfurylase was as high as 5.1 x 10(4) u/mg. The successful application of the enzyme in pyrosequencing was also demostrated.
Asunto(s)
Escherichia coli , Genética , Metabolismo , Proteínas Fúngicas , Genética , Metabolismo , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes , Genética , Saccharomyces cerevisiae , Genética , Análisis de Secuencia de ADN , Métodos , Sulfato Adenililtransferasa , GenéticaRESUMEN
Synechococcus elongatus PCC 7942 was able to grow with several S sources. The sulphur metabolizing enzymes viz. ATP sulphurylase, cysteine synthase, thiosulphate reductase and L- and D-cysteine desulphydrases were regulated by sulphur sources, particularly by sulphur amino acids and organic sulphate esters. Sulphur starvation reduced ATP sulphurylase and cysteine synthase whereas reduced glutathione appreciated Cys degradation activity. With partially purified enzymes apparent Km values for sulphate, ATP, D- and L-Cys, thiosulphate, sulphide and O-acetyl serine were in a range of 12-50 microM. p-Nitrophenyl sulphate inhibited ATP sulphurylase competitively. Met was a feedback inhibitor of several key enzymes.