Dual regulation of the synthesis of the arginine pathway carbamoylphosphate synthase of Saccharomyces cerevisiae by specific and general controls of amino acid biosynthesis

✍ Scribed by Piérard, André ;Messenguy, Francine ;Feller, André ;Hilger, François

• Publisher: Springer
• Year: 1979
• Tongue: English
• Weight: 859 KB
• Volume: 174
• Category: Article
• ISSN: 0026-8925
• DOI: 10.1007/bf00268353

✦ Synopsis

The synthesis of the arginine pathway carbamoylphosphate synthase (CPSase A) of Saccharomyces cerevisiae is subject to two control mechanisms. One mechanism is specific for CPSase A and is exerted by arginine; it probably involves a repressor-operator type of interaction. This "specific" mechanism regulates the expression of gene cpaI coding for the small "glutaminase" subunit of CPSase A but has little influence on the production of the large subunit of the enzyme, a product of gene cpaII. This large component, which alone has no biological significance, accumulates freely under conditions of arginine repression. The second mechanism is general: it controls enzyme synthesis in a number of amino acid biosynthetic pathways in addition to the arginine sequence. Two types of evidence that this "general" mechanism participates in the control of CPSase A synthesis are presented: (1) Derepression upon starvation for any amino acid of which the synthesis is subject to this general control; and (2) repression during growth in amino acid-rich medium. In contrast to the specific mechanism, the "general" mechanism regulates the expression of both the cpaI and cpaII genes.