Effect of valine and the herbicide sulfometuron methyl on acetolactate synthase activity in nuclear and plasmid-borne sulphometuron methyl resistant Saccharomyces cerevisiae strains.
Acetolactate synthase (ALS) specific activity was evaluated in isogenic lines of Saccharomyces cerevisiae carrying the wild-type ILV2 gene or mutations in this gene for resistance to the herbicide sulfometuron methyl (SM). Statistical comparisons were made between two nuclear alleles and among five alleles borne on a YE chimaeric plasmid transformed into a strain carrying a 1.5-kilobase deletion in the nuclear ILV2 gene. Decreased ALS activity of plasmid-borne SM-resistant mutations was shown not to be caused by copy number effects. ALS-specific activity in strains carrying the wild-type ILV2 allele exhibited strong feedback inhibition by valine and was sensitive to SM. All nuclear and plasmid-borne SM-resistance alleles resulted in ALS-specific activity highly resistant to SM and resistant to valine feedback inhibition.
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Department of Biology, University of Saskatchewan, Saskatoon, Canada.
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D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors*; D000483:Alleles; D002467:Cell Nucleus; D003470:Culture Media; D004352:Drug Resistance, Microbial / Q000235:genetics; D006540:Herbicides / Q000494:pharmacology*; D009154:Mutation; D007652:Oxo-Acid-Lyases / Q000037:antagonists & inhibitors*; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D013453:Sulfonylurea Compounds / Q000494:pharmacology*; D014170:Transformation, Genetic; D014633:Valine / Q000494:pharmacology*
D003470:Culture Media; D006540:Herbicides; D013453:Sulfonylurea Compounds; D000095:Acetolactate Synthase; D007652:Oxo-Acid-Lyases; D014633:Valine; C042031:sulfometuron methyl