Effect of Chlorsulfuron, a Potent Inhibitor of Acetohydroxyacid Synthase, on Metabolism of Claviceps purpurea

1988 ◽  
Vol 43 (5-6) ◽  
pp. 403-407 ◽  
Author(s):  
Walter Maier ◽  
Brigitte Schumann ◽  
Detlef Gröger
Keyword(s):  
Amino Acids ◽  
Potent Inhibitor ◽  
Ergot Alkaloids ◽  
Plant Cells ◽  
Branched Chain Amino Acids ◽  
Acetohydroxyacid Synthase ◽  
Claviceps Purpurea ◽  
Sulfonylurea Herbicide ◽  
High Concentrations ◽  
Branched Chain

Chlorsulfuron (CS) is a potent sulfonylurea herbicide inhibiting specifically acetohydroxyacid synthase which catalyzes the first step in the biosynthesis of branched-chain amino acids in plant cells, bacteria and yeast. The peptide portion of some ergot alkaloids contain inter alia branchedchain amino acids. The influence of CS on growth and alkaloid formation in Claviceps was studied. In an ergotoxine strain growth is inhibited by chlorsulfuron in the range of 10-100 μᴍ. Under CS influence ergosine is accumulated besides ergotoxines. Growth inhibition caused by CS could be reversed by addition of ʟ-valine ( ~ 35 mᴍ), but neither by leucine nor isoleucine. Ergosine did not occur under these conditions. Acetohydroxyacid synthase (AHAS) from Claviceps purpurea was partially purified. AHAS preparations are not inhibited even by high concentrations of chlorsulfuron.

Fun with Mutants: Applying Genetic Methods to Problems of Weed Physiology

Weed Science ◽  
1991 ◽  
Vol 39 (3) ◽  
pp. 489-496 ◽  
Author(s):  
Michael L. Christianson
Keyword(s):  
Amino Acids ◽  
Case History ◽  
Potential Problem ◽  
Plant Cells ◽  
Acetolactate Synthase ◽  
Branched Chain Amino Acids ◽  
Successful Development ◽  
Amino Butyric Acid ◽  
Branched Chain ◽  
Whole Plants

Genetics can be a powerful adjunct to just about any kind of physiological study, including weed physiology or weed/herbicide interactions. Making, mapping, and reverting mutations is simple and straightforward. Making mutants can be as simple as isolating variant individuals from the “wild”, as uncomplicated as doing seed mutagenesis in your laboratory, or as sneaky as recovering mutants as sectors in whole plants. The overall principles for successful development of a protocol for seed mutagenesis of weeds are described and potential problem areas noted. These generalities are illustrated with a specific case history, that of chlorsulfuron. Although chlorsulfuron is accurately described as an inhibitor of the synthesis of branched chain amino acids, careful physiological examination suggests that it kills plant cells, not by starvation for amino acids, but by active toxicity of a metabolite, α-amino butyric acid, produced from a precursor available for diversion in cells with inhibited acetolactate synthase (EC 4.1.3.18, ALS). The story of dominant resistance due to an altered ALS enzyme is well known; analysis using additional mutants fleshes out the story of how chlorsulfuron works. Such analysis has the potential to help unravel other problems in weed physiology.

scholarly journals Engineering Herbicide-Tolerance Rice Expressing an Acetohydroxyacid Synthase with a Single Amino Acid Deletion

2020 ◽  
Vol 21 (4) ◽  
pp. 1265
Author(s):  
Jun Fang, ◽  
Changzhao Wan ◽  
Wei Wang ◽  
Liuyin Ma ◽  
Xinqi Wang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Agronomic Traits ◽  
Herbicide Tolerance ◽  
Branched Chain Amino Acids ◽  
Single Amino Acid ◽  
Acetohydroxyacid Synthase ◽  
Sulfometuron Methyl ◽  
Herbicide Tolerant ◽  
Branched Chain

The acetohydroxyacid synthase (AHAS) is an essential enzyme involved in branched amino acids. Several herbicides wither weeds via inhibiting AHAS activity, and the AHAS mutants show tolerance to these herbicides. However, most AHAS mutations are residue substitutions but not residue deletion. Here, residue deletion was used to engineering the AHAS gene and herbicide-tolerant rice. Molecular docking analysis predicted that the W548 of the AHAS was a residue deletion to generate herbicide tolerance. The AHAS-ΔW548 protein was generated in vitro to remove the W548 residue. Interestingly, the deletion led to the tetramer dissociation of the AHAS, while this dissociation did not reduce the activity of the AHAS. Moreover, the W548 deletion contributed to multi-family herbicides tolerance. Specially, it conferred more tolerance to sulfometuron-methyl and bispyribac-sodium than the W548L substitution. Further analysis revealed that AHAS-ΔW548 had the best performance on the sulfometuron-methyl tolerance compared to the wild-type control. Over-expression of the AHAS-ΔW548 gene into rice led to the tolerance of multiple herbicides in the transgenic line. The T-DNA insertion and the herbicide treatment did not affect the agronomic traits and yields, while more branched-chain amino acids were detected in transgenic rice seeds. Residue deletion of W548 in the AHAS could be a useful strategy for engineering herbicide tolerant rice. The increase of branched-chain amino acids might improve the umami tastes of the rice.

Requirements for branched chain amino acids and their interactions in the nematode Caenorhabditis elegans

Nematology ◽  
2000 ◽  
Vol 2 (5) ◽  
pp. 501-506 ◽  
Author(s):  
Dalia Perelman ◽  
Nancy Lu
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Caenorhabditis Elegans ◽  
Branched Chain Amino Acids ◽  
Nematode Caenorhabditis Elegans ◽  
Optimal Range ◽  
C Elegans ◽  
Branched Chain Amino Acid ◽  
High Concentrations ◽  
Branched Chain

AbstractBranched chain amino acid (BCAA) requirements and their interactions were studied in the nematode Caenorhabditis elegans. Optimal, deficiency and toxic levels affecting nematode population growth were determined for each of the three BCAAs. The optimal range for leucine was 0.72-2.8; for isoleucine, 0.86-1.7; and for valine, 0.51-4.1 mg ml-1. Leucine at high concentrations was toxic. When isoleucine and valine were both added at high concentrations, they also exerted a marked toxic effect. The interactions of the branched chain amino acids found among vertebrate animals were not observed in C. elegans. Les besoins relatifs aux amino-acides en chaîne ramifiée et leurs interactions chez le nématode Caenorhabditis elegans - Les besoins relatifs aux amino-acides en chaîne ramifiée (BCAA) et leurs interactions ont été étudiés chez le nématode Caenorhabditis elegans. Les niveaux optimal, de déficience et toxique affectant la croissance de la population du nématode ont été déterminés pour chacune des BCAA. L'optimum est, pour la leucine de 0,72 à 2,8, pour l'isoleucine de 0,86 à 1,7 et pour la valine de 0,51 à 4,1 mg ml-1. A forte concentration la leucine est toxique. Si l'isoleucine et la valine sont ajoutées à forte concentration elles exercent également une action toxique prononcée. Les interactions entre BCAA observées chez les vertébrés ne l'ont pas été chez les C. elegans.

Heterologous Expression and Functional Characterization of Catalytic Subunit of Rice Acetohydroxyacid Synthase

2019 ◽  
Vol 26 (3) ◽  
pp. 176-183
Author(s):  
Ghazaleh Arabzadeh ◽  
Azar Shahpiri
Keyword(s):  
Amino Acids ◽  
Specific Activity ◽  
Feedback Inhibition ◽  
Functional Characterization ◽  
Branched Chain Amino Acids ◽  
Biochemical Properties ◽  
Catalytic Subunit ◽  
Acetohydroxyacid Synthase ◽  
Branched Chain

Background: Acetohydroxyacid Synthase (AHAS) is the first enzyme in the biosynthesis pathway of the branched chain amino acids. AHAS is the common target site of five herbicide chemical groups: sulfonylurea, imidazolinone, triazolopyrimidine, pyrimidinyl-thiobenzoates, and sulfonyl-aminocarbonyl-triazolinone. </P><P> Objective: The purification of protein enabled us to study the physical and biochemical properties of the enzyme. In addition in vitro activity of this enzyme was tested in the presence of four different sulfonylureaherbicides and the feedback regulation of enzyme was analyzed in the presence of branched amino acids. Methods: The gene encoding catalytic subunit of rice AHAS (cOsAHAS) without part of the chloroplast transit sequence was cloned into the bacterial expression vector pET41a and heterologously expressed in Escherichia coli as carboxy-terminal extensions of glutathione-S-transferase (GST).The soluble protein was purified using affinity chromatography. The measurement of GSTOsAHAS activity was performed under optimized conditions at present of branched-chain amino acids and sulfonylurea herbicides independently. Results: The optimum pH and temperature for GST-cOsAHAS activity was 8.0 and 37 °C, respectively. The specific activity and Km value of this enzyme toward pyruvate were 0.08 U/mg and 30 mM, respectively.GST-cOsAHAS was inhibited by herbicides tribenuron, sulfosulfuron, nicosulfuron and bensulfuron while the enzyme was insensitivieto end products. Conclusion: These results suggest that the recombinant form of GST-cOsAHAS is functionally active and carries the binding site for sulfynylurea herbicides. Furthermore, GST-cOsAHAS was insensitive to feedback inhibition by endproducts which indicates the existence of a regulator subunit in rice AHAS as previously has been described in other plant AHASs.

Acetohydroxyacid Synthase Inhibitors: N-Phthalyl-ʟ-valine Anilide and Related Compounds

1985 ◽  
Vol 40 (9-10) ◽  
pp. 652-656 ◽  
Author(s):  
John L. Huppatz ◽  
John E. Casida
Keyword(s):  
Amino Acids ◽  
Zea Mays ◽  
Root Growth ◽  
Branched Chain Amino Acids ◽  
Aminobutyric Acid ◽  
Acetohydroxyacid Synthase ◽  
Branched Chain ◽  
Partial Activity ◽  
Derivatives Of ◽  
Related Compounds

Abstract The potency of ʟ-valine as an inhibitor of Zea mays acetohydroxyacid synthase (AHAS) is increased more than 80110-fold on conversion to its N-phthalyl anilide derivative which is active at 2 µᴍ. The ᴅ-valine, α-aminobutyric acid, isoleucine and phenylalanine analogs are 11- to 43-fold less potent, and similar N-phthalyl anilide derivatives of other branched-chain amino acids are essentially inactive. Full potency is retained on replacing the phthalimide moiety of the valine anilide with cyclohexane-1,2-dicarboximide or 1-cyclohexene-1.2-dicarboximide groups and partial activity with 4-cyclohexene-1,2-dicarboximide and methyl- or dimethylmaleimide groups. Inhibition of the enzyme and of root growth by the valine derivatives may result from binding at or near the site involved in feedback control of AHAS by ʟ-valine.

Rapid Diagnosis of Als/Ahas-Resistant Weeds

1993 ◽  
Vol 7 (2) ◽  
pp. 519-524 ◽  
Author(s):  
B. Clifford Gerwick ◽  
Linda C. Mireles ◽  
Robert J. Eilers
Keyword(s):  
Amino Acids ◽  
Acetolactate Synthase ◽  
Branched Chain Amino Acids ◽  
Rapid Diagnosis ◽  
Acetohydroxyacid Synthase ◽  
Number Of Species ◽  
Apical Leaf ◽  
Diagnosis Method ◽  
Branched Chain ◽  
Leaf Disks

A method to rapidly identify acetolactate synthase/acetohydroxyacid synthase (ALS/AHAS)-resistant weeds is described based upon the differential accumulation of acetoin in the presence and absence of an ALS/AHAS inhibitor herbicide. Acetoin accumulation is induced by inhibition of ketol-acid reductoisomerase (KARI), the enzyme immediately following ALS/AHAS in the biosynthesis of branched-chain amino acids. Inhibition of ALS/AHAS prevents the build up of acetoin and forms the basis for distinguishing between sensitive and resistant biotypes. A new inhibitor of KARI, 1,1-cyclopropanedicarboxylic acid (CPCA), is described and was found to cause acetoin accumulation in velvetleaf leaf disks over the concentration range of 2 to 100 000 μM. In the presence of CPCA, a number of species important to monitor for ALS/AHAS resistance were found to accumulate acetoin at rates sufficient for resistance diagnosis in 2 to 8 h. In velvetleaf, the youngest apical leaf was found to be the most active in acetoin accumulation. The resistance diagnosis method was validated by clearly distinguishing between imazaquin-sensitive and imazaquin-resistant cocklebur biotypes.

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