CLONING AND SEQUENCING OF SCHIZOSACCHAROMYCES-POMBE CAR1 GENE ENCODING ARGINASE - EXPRESSION OF THE ARGININE ANABOLIC AND CATABOLIC GENES IN RESPONSE TO ARGININE AND RELATED METABOLITES

We report here the cloning and sequencing of the gene encoding arginas e (carl) from Schizosaccharomyces pombe. Since no arginase-less strain exists in this organism, we cloned the gene by functional complementa tion of a carl mutant strain from Saccharomyces cerevisiae. The S. pom be carl gene encodes a 323 amino acids polypeptide sharing identity wi th arginases from different organisms. Measurements of arg3, arg11 and car1 mRNA under different growth conditions confirm the very weak rep ression by arginine of the two anabolic genes and show that the induct ion of arginase synthesis operates at a transcriptional level. The pro moter of S. pombe carl gene does not contain the 'arginine boxes' defi ned as the target of the ARGR-MCM1 proteins in the promoters of the ar ginine co-regulated genes in S. cerevisiae. The heterologous expressio n of S. pombe cal l gene in S. cerevisiae is independent of the ARGRII gene product (ArgRIIp/Arg8lp). Determination of arginine, ornithine a nd citrulline intracellular concentrations shows the efficiency of the different controls operating in S. cerevisiae, and also indicates tha t in S. pombe enzyme compartmentation is not always sufficient to cont rol the arginine metabolic flux.