This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Subramanian, M. V. Articles by Jachetta, J. J. Search for Related Content PubMed PubMed Citation Articles by Subramanian, M. V. Articles by Jachetta, J. J. Agricola Articles by Subramanian, M. V. Articles by Jachetta, J. J.

Metabolism and Enzymology

Properties of Mutant Acetolactate Synthases Resistant to Triazolopyrimidine Sulfonanilide

DowElanco, Walnut Creek, California 94598

Triazolopyrimidine sulfanilides are a class of highly active herbicides whose primary target is acetolactate synthase. Spontaneous mutants of tobacco (Nicotiana tabacum) (KS-43) and cotton (Gossypium hirsutum) (PS-3 and DO-2) resistant to triazolopyrimidine sulfonanilide were selected in tissue culture. Acetolactate synthase partially purified from the three mutants were 80- to 1000-fold less sensitive to inhibition by the compound compared with the corresponding wild-type enzyme. The mutants also varied in the cross-resistance pattern to other acetolactate synthase inhibiting herbicides in the sulfonylurea, imidazolinone, and pyrimidyl-oxy-benzoate chemical families. Thus, acetolactate synthase from KS-43, PS-3, and DO-2 cultures have different mutations. The affinities for pyruvate, thiamine pyrophosphate, as well as the activity of the mutant enzymes were found to be comparable to the corresponding wild-type enzymes. However, the enzyme from PS-3 was highly resistant to feedback inhibition by valine and leucine. In contrast, acetolactate synthase from KS-43 and DO-2 were inhibited by valine and leucine to nearly the same extent as the wild-type enzymes. Also, PS-3 cultures accumulated much higher levels of the branched chain amino acids compared to the wild-type cotton culture. The mutation in the PS-3 enzyme has therefore rendered it insensitive to feedback regulation by valine and leucine.

This article has been cited by other articles:

				C. J. Pozniak, I. T. Birk, L. S. O'Donoughue, C. Menard, P. J. Hucl, and B. K. Singh Physiological and Molecular Characterization of Mutation-Derived Imidazolinone Resistance in Spring Wheat Crop Sci., July 1, 2004; 44(4): 1434 - 1443. [Abstract] [Full Text] [PDF]

				C. J. Pozniak and P. J. Hucl Genetic Analysis of Imidazolinone Resistance in Mutation-Derived Lines of Common Wheat Crop Sci., January 1, 2004; 44(1): 23 - 30. [Abstract] [Full Text] [PDF]

				P. Bernasconi, A. R. Woodworth, B. A. Rosen, M. V. Subramanian, and D. L. Siehl A Naturally Occurring Point Mutation Confers Broad Range Tolerance to Herbicides That Target Acetolactate Synthase J. Biol. Chem., July 21, 1995; 270(29): 17381 - 17385. [Abstract] [Full Text] [PDF]