FURTHER DEFINITION OF THE SEQUENCE AND POSITION REQUIREMENTS OF THE ARGININE CONTROL ELEMENT THAT MEDIATES REPRESSION AND INDUCTION BY ARGININE IN SACCHAROMYCES-CEREVISIAE

Repression or induction of the genes involved in arginine biosynthesis or catabolism, respectively, both require participation of the ArgRp/ Mcm1p regulatory complex. Our previous work showed that those opposite effects were mediated by a similar arginine-responsive element of 23 nucleotides (that we now call ARC, for ARginine Control) situated clos e to the start of transcription in the repressed promoters and far ups tream of the TATA-element in the induced promoters. To define more pre cisely the sequence and position requirements of the ARC element, we h ave now characterized by mutagenesis the promoter elements of the argi nine-repressible ARG1 and ARG8 genes. We also identify a functional AR C in the CPA1 promoter, thereby confirming, in agreement with our prev ious mRNA pulse-labelling data, the participation of a transcriptional component in the arginine regulation of that gene otherwise submitted to a translational regulation. From the 12 ARC elements now character ized, we have derived a consensus sequence and show that such a synthe tic element is able to mediate ArgRp/Mcm1p-dependent arginine regulati on. An important new finding illustrated by ARG1 and CPA1, is that con trary to what all the previous data suggested, repression can be media ted by ARC elements located far upstream of the TATA-box. The new data suggest that the arginine repressor might inhibit transcription in an active process.