Regulation of ATP-sulfurylase and Adenosine 5'-phosphosulfate Sulfotransferase by the Sulfur and the Nitrogen Source in Heterotrophic Cell Suspension Cultures of Paul's Scarlet Rose

Abstract

Summary The effect of the sulfur and the nitrogen source on the activity of adenosine 5'-phosphosulfate sulfotransferase (APSSTase) from cell suspension cultures of Rosa sp.(Paul's Scarlet rose) was studied.ATP-sulfurylase (EC 2.7.7.4), nitrate reductase (EC 1.6.6.1) and O-acetyl-L-serine sulfhydrylase (EC 4.2.99.9) were measured for comparison.APSSTase activity was increased by 200% after omission of a sulfur source and by 50% when cells were cultivated with NH 4 + instead of NO 3 - .Lack of a nitrogen source or cultivation with H 2 S or cysteine as sulfur sources induced a decrease in APSST ase activity to a very low level.The decrease induced by H 2 S and cysteine was less pronounced in the presence of NH 4 + .ATP-sulfurylase was increased by 100% in cultures without a sulfur source, whereas lack of a nitrogen source or NH 4 + instead of NO 3 - had no effect on its activity during 24 h.Cysteine decreased this enzyme activity by 40% after 24h.Taken together our results are consistent with the idea that APSSTase plays a central role in regulating sulfate assimilation and in coordinating it with nitrate assimilation, whereas A TP-sulfurylase seems to have an accessory function in these respects.