Derepression of arylsulfatase activity by sulfate starvation in chlorella fusca

Abstract

Arylsulfatase activity was detected in the green alga Chlorella fusca 211-8b during sulfur starvation. 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 aftera lag-period of about 3 h; addition cycloheximide prevented arylsulfatase formation, suggesting the participation of protein Addition of sulfate to cultures with active arylsulfatase led to a decay of this enzyme, whereas addition of sulfate andcycloheximide 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 arylsulfataseis 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. © 1987, Walter de Gruyter. All rights reserved.