Correlation between restriction map, genetic map and catalytic functions in the gene complex URA2.
We replaced the URA2 gene by six different deleted alleles constructed in vitro by Bg/II digestion in order to correlate the genetic map with the restriction map and to define the regions coding for the different functions of the carbamylphosphate synthetase--aspartate transcarbamylase complex (CPSase-ATCase). We also enlarged the collection of ura2 point mutations by using a positive selection method based on resistance to the toxic accumulation of ureidosuccinic acid (USA). Of the new independent mutations nine mapped in the intermediary zone, a previously defined mutationless region localized between regions coding for CPSase and ATCase. This shows that the former definition resulted from analysis of a limited number of mutants (40). The study of an allele deleted in the intermediary zone shows that this sequence codes for a protein region necessary for the feedback inhibition of the CPSase-ATcase enzyme complex. The CPSase- ATCase- phenotype of 26 mutants resistant to USA accumulation shows the importance of the in vivo channelling of carbamylphosphate in the CPSase-ATCase complex for USA and subsequent pyrimidine biosynthesis. Finally, our results confirm that the CPSase and ATCase activities are separate functions.
Potier
S
S
Laboratoire de Génétique Physiologique, Institut de Biologie Moléculaire et Cellulaire du C.N.R.S., Strasbourg, France.
Souciet
J L
JL
Lacroute
F
F
D001221:Aspartate Carbamoyltransferase / Q000235:genetics*; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000235:genetics*; D004262:DNA Restriction Enzymes; D005796:Genes; D005800:Genes, Fungal; D008025:Ligases / Q000235:genetics*; D009097:Multienzyme Complexes / Q000235:genetics*; D009154:Mutation; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*
D009097:Multienzyme Complexes; C019820:carbamoyl phosphate synthase-aspartatecarbamoyl transferase complex; D001221:Aspartate Carbamoyltransferase; D004262:DNA Restriction Enzymes; D008025:Ligases; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)