Mechanism of choline O-sulphate utilization in fungi.
1. The position of the enzyme blocks in a number of parathiotrophic mutants of Aspergillus nidulans A 69 and mutants A and C of a biotinless mutant of Aspergillus nidulans were examined by nutritional and heterokaryosis experiments and by assay in vitro of enzyme systems and specific enzymes. 2. The mutants were in five groups: A and C blocked at sulphate transport; gamma at ATP sulphurylase; iota at adenosine 5'-sulphatophosphate kinase; eta at the adenosine 3'-phosphate 5'-sulphatophosphate reductase system; alpha, beta and zeta between sulphite and thiosulphate. 3. The ability of the various mutants to synthesize choline O-sulphate in vivo and in vitro and to utilize choline O-sulphate as a source of sulphur indicated that the utilization of endogenously formed choline O-sulphate involved the splitting off of inorganic sulphate, which was then reduced. 4. Choline O-sulphate acted as a source of choline for cholineless strains of Neurospora crassa, suggesting that choline O-sulphate breakdown occurred by simple hydrolysis involving a choline sulphatase. 5. After de-repression of mycelia by growing for a period on a sulphur-free medium the presence of choline sulphatase in physiologically significant amounts was demonstrated in all the A. nidulans strains tested. 6. Choline O-sulphate is transported across the mycelial wall by a mechanism different to that responsible for inorganic sulphate transport.
D000227:Adenine Nucleotides; D001230:Aspergillus / Q000378:metabolism*; D002794:Choline / Q000096:biosynthesis / Q000378:metabolism*; D004794:Enzyme Repression; D005827:Genetics, Microbial; D008954:Models, Biological; D009154:Mutation; D009713:Nucleotidyltransferases; D010770:Phosphotransferases; D013431:Sulfates / Q000096:biosynthesis / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism; D013460:Sulfur Isotopes
D000227:Adenine Nucleotides; D013431:Sulfates; D013460:Sulfur Isotopes; D013455:Sulfur; D010770:Phosphotransferases; D009713:Nucleotidyltransferases; D002794:Choline