Choline-O-sulphate utilization inAspergillus nidulans

Abstract

SUMMARYThe role of choline-O-sulphate (COS) as a sulphur storage compound inAspergillus nidulanswas examined by comparing a normal strain and one unable to utilize COS in a sulphur-starvation experiment designed to measure the mobilization of sulphur stores. Efforts to isolate the necessary mutants deficient in choline sulphatase activity produced two nutritionally distinct classes of mutants unable to utilize COS. They were found to be allelic on the basis of genetic complementation and fine structures mapping and represent either leaky or tight mutants with respect to choline sulphatase activity. One of these mutants with no detectable choline sulphatase activity was selected for a growth experiment which demonstrated that COS is a major, though not the only source of the endogenous sulphur supply which can be mobilized during growth in sulphur-limiting conditions.