ISOLATION AND CHARACTERIZATION OF THE YEAST ARGRII GENE INVOLVED IN REGULATING BOTH ANABOLISM AND CATABOLISM OF ARGININE

ARGRII is 1 of the 3 [Saccharomyces cerevisiae]. From a pool of hybrid plasmids carrying Sau3A fragments representing the entire yeast genome, a DNA fragment containing the regulatory gene ARGRII was cloned by complementation of an argRII- mutation, which prevents growth on ornithine as sole N source. Cells containing the cloned DNA regained the ability to repress the synthesis of anabolic enzymes and to induce the synthesis of the catabolic ones, when arginine is present. The 6.2 kb [kilobase] cloned DNA fragment encodes 5 transcripts (2.8, 1.3, 0.75, 0.45, 0.45 kb), which were located by S1 endonuclease mapping. By marker rescue the argRII- mutations were mapped in the DNA region coding for the 2.8 kb transcript, showing its importance in the control mechanism. Subcloning experiments confirm this result. At present, the role of the 0.75 and 1.3 kb transcripts in the ARGR+ phenotype is unclear.