Derepression of Arylsulfatase Activity by Sulfate Starvation in Chlorella fusca

Inge Niedermeyer, Susanne Biedlingmaier, and Ahlert Schmidt Botanisches Institut, Universität München, Menzinger Str. 67, D-8000 München 19, Bundesrepublik Deutschland Z. Naturforsch. 42c, 530—536 (1987); received October 27, 1986 Chlorella, Arylsulfatase, Sulfate Starvation, Derepression by Starvation Arylsulfatase activity was detected in the green alga Chlorella fusca 211-8b during sulfur starva­ tion. No activity was present during growth on sulfate, whereas activity was found with sulfur sources as growth-limiting factor including L-cysteine and L-methionine. Arylsulfatase activity was found after transfer to sulfate starvation conditions after a lag-period of about 3 h; addition of cycloheximide prevented arylsulfatase formation, suggesting the participation of protein synthe­ sis. Addition of sulfate to cultures with active arylsulfatase led to a decay of this enzyme, whereas addition of sulfate and cycloheximide prevented this decay suggesting that protein synthesis is also needed for degradation of arylsulfatase activity. The Km for p-nitrophenyl sulfate was determined to be 0.8 m M . The activity of the arylsulfatase is not affected by sulfate or phosphate, however it is inhibited strongly by sulfite, cyanide and boric acid and therefore is classified according to Dogson and Spencer (Meth. Biochem. Anal. 4, 211-254 (1957) as an arylsulfatase of type I.