Mutants affecting amino acid cross-pathway control inNeurospora crassa

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Abstract
Summary: Arginine-requiring mutants ofNeurospora crassawere isolated using a strain partially impaired in an enzyme of the arginine pathway (bradytroph). Among these, five strains were found which carry mutations at a new locus,cpc-1+. The recessivecpc-1alleles interfere with the cross-pathway control of amino acid biosynthetic enzymes. The enzymes studied, three of arginine and one each of histidine and lysine biosynthesis, fail to derepress under conditions which normally result in elevation of enzyme concentration, namely arginine, histidine or tryptophan limitation. Enzymes not involved in amino acid biosynthesis are still able to derepress in the presence ofcpc-1. In wild-type backgound, i.e. with the bradytroph replaced,cpc-1strains lose the original arginine-requirement.cpc-1mutations confer sensitivity of growth to 3-amino-1,2,4-triazole.