Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Relationships among the herbicide and functional sites of acetohydroxy acid synthase from Chlorella emersonii

  • 42 Accesses

  • 7 Citations


The properties of acetohydroxy acid synthase (AHAS, EC from wild-type Chlorella emersonii (var. Emersonii, CCAP-211/11n) and two spontaneous sulfometuron methyl (SMM)-resistant mutants were examined. The AHAS from both mutants was resistant to SMM and cross-resistant to imazapyr (IM) and the triazolopyrimidine sulfonanilide herbicide XRD-498 (TP). The more-SMM-resistant mutant had AHAS with altered catalytic parameters (K m, specificity), but unchanged sensitivity to the feedback inhibitors valine and leucine. The second mutant enzyme was less sensitive to the feedback inhibitors, but had otherwise unchanged kinetic parameters. Inhibition-competition experiments indicated that the three herbicides (SMM, IM, TP) bind in a mutually exclusive manner, but that valine can bind simultaneously with SMM or TP. The three herbicide classes apparently bind to closely overlapping sites. We suggest that the results with C. emersonii and other organisms can all be explained if there are separate binding sites for herbicides, feedback inhibitors and substrates.

This is a preview of subscription content, log in to check access.



acetohydroxy acid synthase








triazolopyrimidine sulfonanilide herbicide XRD-498


enzyme specificity


sulfometuron methyl


  1. Gollop, N., Barak, Z., Chipman, D.M. (1988) Assay of products of acetolactate synthase. Methods Enzymol. 166, 234–240

  2. Gollop, N., Damri, B., Barak, Z., Chipman, D.M. (1989) Kinetics and mechanism of acetohydroxyacid synthase isozyme III from Escherichia coli. Biochemistry 28, 6310–6317

  3. Hall, L.M., Devine, M.D. (1990) Cross resistance of a chlorsulforon-resistant biotype of Stellaria media to a triazolopyrimidine herbicide. Plant Physiol. 93, 962–966

  4. Hawkes, T.R., Howard, J.L., Pontin, S.E. (1989) Herbicides that inhibit the biosynthesis of branched chain amino acids. In: Herbicides and plant metabolism (SEM seminar series), pp. 113–137, Dodge, E.D., ed., Cambridge Academic Press, Cambridge

  5. Kishore, G.M., Shah, D.M. (1988) Amino acid biosynthesis inhibitors as herbicides. Annu. Rev. Biochem. 57, 627–663

  6. Landstein, D., Chipman, D.M., Arad (Malis), S., Barak, Z. (1990) Acetohydroxyacid synthase activity in Chlorella emersonii under autoand heterotrophic growth conditions. Plant Physiol. 94, 614–620

  7. LaRossa, R.A., Schloss, J.V. (1984) The sulfonylurea herbicide sulfometuron methyl is an extremely potent and selective inhibitor of acetolactate synthase in Salmonella typhimurium. J. Biol. Chem. 259, 8753–8757

  8. Lowry, O.H., Rosebrough, N.J., Farr, A.L., Randall, H.J. (1951) Protein measurement with the folin phenol reagent. J. Biol. Chem. 193, 265–275

  9. Maiti, S.N., Zink, M.W., Rank, G.H. (1988) Effect of valine and the herbicide sulfometuron methyl on acetolactate synthase activity in nuclear and plasmid-born sulfometuron methyl resistant Saccharomyces cerevisiae strains. Can. J. Microbiol. 34, 680–685

  10. Mazur, B.J., Falco, S.C. (1989) The development of herbicide resistant crops. Annu. Rev. Plant Physiol. Mol. Biol. 40, 441–470

  11. Miflin, B.J., Cave, P.R. (1972) The control of leucine, isoleucine and valine biosynthesis in a range of higher plants. J. Exp. Bot. 23, 511–516

  12. Oda, Y., Nakano, O.Y., Kitaoka, S. (1982) Properties and regulation of valine-sensitive acetolactate synthase from mitochondria of Euglena gracilis. J. Gen. Microbiol. 128, 1211–1216

  13. Rathinasabapathi, B., King, J. (1991) Herbicide resistance in Datura innoxia: kinetic characterization of acetolactate synthase from wild-type and sulfonylurea-resistant cell variants. Plant Physiol. 96, 255–261

  14. Relton, J.M., Wallsgrove, R.M., Bourgin, J.P., Bright, S.W. (1986) Altered feedback sensitivity of acetohydroxy acid synthase from valine-resistant mutants of tobacco (Nicotiana tabacum L.). Planta 169, 46–50

  15. Saari, L.L., Cotterman, J.C., Primiani, M.M. (1990) Mechanism of sulfonylurea herbicide resistance in the broadleaf weed, Kochia scoparia. Plant Physiol. 93, 55–61

  16. Saxena, P., King, J. (1988) Herbicide resistance in Datura innoxia. Cross-resistance of sulfonylurea resistant lines to imidazolinones. Plant Physiol 86, 863–867

  17. Saxena, P., King, J. (1990) Lack of cross resistance of imidazolinone-resistant cell lines of Datura innoxia P. Mill, to chlorsulfuron: evidence for separable sites of action on the target enzyme. Plant Physiol 94, 1111–1115

  18. Schloss, J.V., Aulabaugh, A. (1990) Acetolactate synthase and ketol acid reductoisomerase a search for reason and a reason for search. In: Biosynthesis of branched chain amino acids, pp. 329–356, Barak, Z., Chipman, D.M., Schloss, J.V., eds. VCH and Balaban, Weinheim and Rehovot

  19. Schloss, J.V., Ciskanik, L.M., Van Dyk, T.E. (1988) Origin of the herbicide binding site of acetolactate synthase. Nature 331, 360–362

  20. Shaner, D.L., Singh, B.K., Stidham, M.A. (1990) Interaction of imidazolinones with plant acetohydroxy acid synthase: Evidence for in vivo binding and competition with sulfometuron methyl. J. Agric. Food Chem. 38, 1279–1282

  21. Soeder, C.J., Ried, A., Strotmann, H. (1964) Hemmwirkung von CO2 auf späte Stadien der Zellentwicklung von Chlorella. Beitr. Biol. Pflanz. 46, 150–171

  22. Subramanian, M.V., Hung H.U., Dias, J.M., Miner, V.M., Butler, J.H., Jachetta, J.J. (1990) Properties of mutant acetolactate synthase resistant to triazolopyrimidine sulfonanilide. Plant Physiol. 94, 239–244

  23. Subramanian, M.V., Loney-Gallant, V., Dias, J.M., Mireles, L.C. (1991) Acetolactate synthase inhibiting herbicides bind to the regulatory site. Plant Physiol. 96, 310–313

  24. Tanaka, H., Kuwana, H. (1984) A Basal unit of valine sensitive acetolactate synthase of Neurospora crassa. Biochem. Biophys. Res. Commun. 123, 418–423

  25. Umbarger, H.E. (1987) Biosynthesis of the branched-chain amino acids. In: Escherichia coli and Salmonella typhimurium, cellular and molecular biology, vol 1, pp. 352–365, Neidhardt, F.C., Ingraham, J.L., Low, K., Magasanik, B., Schaechter, M., Umbarger, H.E. eds, American Society for Microbiology, Washington, DC

  26. Winder, T., Spalding, M.H. (1988) Imazaquin and chlorsulforon resistance and cross resistance in mutants of Chlamydomonas reinhardtii. Mol. Gen. Genet. 213, 394–399

Download references

Author information

Correspondence to Ze'ev Barak.

Additional information

This research was supported in part by the United States — Israel Binational Science Foundation (BSF), Jerusalem, Israel (Grant 86-00205) and the Fund for Basic Research, Israel Academy of Sciences.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Landstein, D., Arad, S.(., Barak, Z. et al. Relationships among the herbicide and functional sites of acetohydroxy acid synthase from Chlorella emersonii . Planta 191, 1–6 (1993). https://doi.org/10.1007/BF00240889

Download citation

Key words

  • Acetolactate synthase
  • Chlorella (mutant)
  • Imidazolinone
  • Mutant (herbicide resistance)
  • Sulfonylurea
  • Triazolopyrimidine sulfonanilide