ISSN:
1617-4623
Keywords:
Deletion mapping
;
Feedback inhibition
;
Channelling
;
Carbamylphosphate synthetase
;
Aspartate transcarbamylase complex
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00329655
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