title: Molecular cloning and characterization of the cys-3 regulatory gene of Neurospora crassa.
abstract: The regulatory gene cys-3+ controls the synthesis of a number of enzymes involved in sulfur metabolism. cys-3 mutants show a multiple loss of enzymes in different pathways of sulfur metabolism. The cys-3+ gene was isolated by transformation of an aro-9 qa-2 cys-3 inl strain with a clone bank followed by screening with the "sib selection" method. The library used (pRAL1) contained inserts of Sau3a partial digest fragments of about 9 kilobases as well as the Neurospora qa-2+ gene. Double selection for qa-2+ and cys-3+ function was carried out. The transformants obtained with the isolated cys-3+ clone show recovery of the enzyme activities associated with the cys-3 mutation (e.g., arylsulfatase and sulfate permease). Restriction fragment length polymorphism experiments confirmed the identity of the clone, mRNA studies with Northern blots show that the expression of the cys-3+ gene is inducible. In contrast to cys-3+, the cys-3 (P22) mutant gene was not expressed at a higher level under sulfur-derepressed conditions.
mesh_terms: D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D005800:Genes, Fungal; D005809:Genes, Regulator; D009491:Neurospora / Q000235:genetics*; D009492:Neurospora crassa / Q000235:genetics* / Q000378:metabolism; D012150:Polymorphism, Restriction Fragment Length; D013455:Sulfur / Q000378:metabolism; D014170:Transformation, Genetic
chemical_list: D013455:Sulfur