Herbicide-Resistant Mutations in Acetolactate Synthase Can Reduce Feedback Inhibition and Lead to Accumulation of Branched-Chain Amino Acids

Masaki Endo, Tsutomu Shimizu, Tamaki Fujimori, Shuichi Yanagisawa, Seiichi Toki

Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Life Science Research Institute, Kumiai Chemical Industry Co. Ltd., Shizuoka, Japan.
Plant Genome Engineering Research Unit, Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, Japan.

DOI: 10.4236/fns.2013.45067                

Abstract

The branched-chain amino acids (BCAAs) valine, leucine and isoleucine are essential amino acids that are critical for animal growth and development. Animals need to obtain BCAAs from their diet because they cannot synthesize them. Plants are the ultimate source of these amino acids. Acetolactate synthase (ALS) is the first common enzyme in the biosynthesis of BCAAs. The metabolic control of BCAA biosynthesis involves allosteric regulation of ALS by the end-products of the pathway, i.e., valine, leucine and isoleucine. ALS holoenzyme seems to consist of two large catalytic subunits and two small regulatory subunits. In a previous study, using homologous recombination dependent gene targeting we created rice plants in which W548Land S627I mutations were induced into the endogenous gene encoding the ALS catalytic subunit. These two amino acid substitutions conferred hypertolerance to the ALS-inhibiting herbicide bispyripac-sodium. In this study, we revealed that feedback regulation by valine and leucine was reduced by these two amino acid substitutions. Furthermore, in leaves and seeds of ALS mutants with W548Land/or S627I substitution, a 2- to 3-fold increase in BCAAs was detected. Our results suggest that the ALS catalytic subunit is also involved in feedback regulation of ALS, and that judicious modification of the regulatory and catalytic subunits of ALS-coding genes by gene targeting can lead to the efficient accumulation of BCAA in plants.

Keywords

Rice; Acetolactate Synthase; Herbicide-Resistance; Branched-Chain Amino Acids

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	J. D. Fernstrom, “Branched-Chain Amino Acids and Brain Function,” The Journal of Nutrition, Vol. 135, No. 6, 2005, pp. 1539-1546.
[2]	K. S. Nair and K. R. Short, “Hormonal and Signaling Role of Branched-Chain Amino Acids,” Journal of Nutrition, No. 135, Vol. 6, 2005, pp. 1547S-1552S.
[3]	D. Chipman, Z. Barak and J. V. Schloss, “Biosynthesis of 2-Aceto-2-Hydroxy Acid; Acetolactate Synthases and Acetohydroxyacid Synthases,” Biochimica et Biophysica Acta (BBA)—Protein Structure and Molecular Enzymology, Vol. 1385, No. 2, 1998, pp. 401-419. doi:10.1016/S0167-4838(98)00083-1
[4]	B. J. Miflin and P. R. Cave, “The Control of Leucine, Isoleucine and Valine Biosynthesis in a Range of Higher Plants,” Journal of Experimental Botany, Vol. 23, No. 75, 1972, pp. 511-516. doi:10.1093/jxb/23.2.511
[5]	C. A. Corbett and F. J. Tardif, “Detection of Resistance to Acetolactate Synthase Inhibitors in Weeds with Emphasis on DNA-Based Techniques: A Review,” Pest Management Science, Vol. 7, No. 62, 2006, pp. 584-597. doi:10.1002/ps.1219
[6]	M. Vyazmensky, C. Sella, Z. Barak and D. M. Chipman, “Isolation and Characterization of Subunits of Acetohydroxy Acid Synthase Isozyme III and Reconstitution of the Holoenzyme,” Biochemistry, Vol. 35, No. 32, 1996, pp. 10339-10346. doi:10.1021/bi9605604
[7]	D. M. Chipman, R. G. Duggleby and K. Tittmann, “Mechanisms of Acetohydroxyacid Synthases,” Current Opinion in Chemical Biology, Vol. 9, No. 5, 2005, pp. 475-481. doi:10.1016/j.cbpa.2005.07.002
[8]	R. G. Duggleby, J. A. McCourt and L. W. Guddat, “Structure and Mechanism of Inhibition of Plant Acetohydro xyacid Synthase,” Plant Physiology and Biochemistry, Vol. 46, No. 3, 2008, pp. 309-324. doi:10.1016/j.plaphy.2007.12.004
[9]	Y. T. Lee and R. G. Duggleby, “Identification of the Regulatory Subunit of Arabidopsis thaliana Acetohydro xyacid Synthase and Reconstitution with Its Catalytic Subunit,” Biochemistry, Vol. 40, No. 23, 2001, pp. 6836-6844. doi:10.1021/bi002775q
[10]	Y. T. Lee and R. G. Duggleby, “Regulatory Interactions in Arabidopsis thaliana Acetohydroxyacid Synthase,” FEBS Letter, Vol. 512, No. 1-3, 2002, pp. 80-184. doi:10.1016/S0014-5793(02)02253-6
[11]	S. Mendel, T. Elkayam, C. Sella, V. Vinogradov, M. Vyazmensky, D. M. Chipman and Z. Barak, “Acetohy droxyacid Synthase: A Proposed Structure for Regulatory Subunits Supported by Evidence from Mutagenesis,” Journal of Molecular Biology, Vol. 307, No. 1, 2001, pp. 465-477. doi:10.1006/jmbi.2000.4413
[12]	S. Mendel, M. Vinogradov, M. Vyazmensky, D. M. Chip man and Z. Barak, “The N-Terminal Domain of the Regulatory Subunit Is Sufficient for Complete Activation of Acetohydroxyacid Synthase III from Escherichia coli,” Journal of Molecular Biology, Vol. 325, No. 2, 2003, pp. 275-284. doi:10.1016/S0022-2836(02)01142-7
[13]	A. Kaplun, M. Vyazmensky, Y. Zherdev, I. Belenky, A. Slutzker, S. Mendel, Z. Barak, D.M. Chipman and B. Shaanan, “Structure of the Regulatory Subunit of Acetohydroxyacid Synthase Isozyme III from Escherichia coli,” Journal of molecular Biology, Vol. 357, No. 3, 2006, pp. 951-963. doi:10.1016/j.jmb.2005.12.077
[14]	G. W. Haughn and C. R. Somerville, “A Mutation Causing Imidazolinone Resistance Maps to the Csr1 Locus of Arabidopsis thaliana,” Plant Physiology, Vol. 92, No. 4, 1986, pp. 1081-1085. doi:10.1104/pp.92.4.1081
[15]	K. Sathasivan, G. W. Haughn and N. Murai, “Molecular Basis of Midazolinone Herbicide-Resistance in Arabidopsis thaliana var Columbia,” Plant Physiology, Vol. 97, No. 3, 1991, pp. 1044-1050. doi:10.1104/pp.97.3.1044
[16]	M. Endo, K. Osakabe, K. Ono, H. Handa, T. Shimizu and S. Toki, “Molecular Breeding of a Novel Herbicide-Tolerant Rice by Gene Targeting,” The Plant Journal, Vol. 52, No. 1, 2007, pp. 157-166. doi:10.1111/j.1365-313X.2007.03230.x
[17]	T. Shimizu, K. Kaku, K. Kawai, T. Miyazawa and Y. Tanaka, “Molecular Characterization of Acetolactate Synthase in Resistant Weeds and Crops,” In: J. M. Clark and H. Ohkawa, Eds., ACS Symposium Series 899: Environmental Fate and Safety Management of Agrochemicals, American Chemical Society, Washington DC, 2005, pp. 255-271.
[18]	Q. Yu, H. Han, M. M. Vila-Aiub and S. B. Powles, “AHAS Herbicide-Resistance Endowing Mutations: Effect on AHAS Functionality and Plant Growth,” Journal of Experimental Botany, Vol. 61, No. 14, 2010, pp. 3925-3934. doi:10.1093/jxb/erq205
[19]	J. Ashigh and F. J. Tardif, “An Ala205Val Substitution in Acetohydroxyacid Synthase of Eastern Black Nightshade (Solanum ptychanthum) Reduces Sensitivity to Herbicides and Feedback Inhibition,” Weed Science, Vol. 55, No. 6, 2007, pp. 558-565. doi:10.1614/WS-07-054.1
[20]	C. V. Eberlein, M. J. Guttieri, P. H. Berger, J. K. Fellman, C. A. Mallory-Smith, D. C. Thill, R. J. Baerg and W. R. Belknap, ”Physiological Consequence of Mutation for ALS-Inhibitor Resistance,” Weed Science, Vol. 47, No. 4, 1999, pp. 383-392.
[21]	C. V. Eberlein, M. J. Guttieri, C. A. Mallory-Smith, D. C. Thill and R. J. Baerg, “Altered Acetolactate Synthase Activity in ALS-Inhibitor Resistant Prickly Lettuce (Lactuca serriola),” Weed Science, Vol. 45, No. 2, 1997, pp. 212-217.
[22]	C. Preston, L. M. Stone, M. A. Rieger and J. Baker, “Multiple Effects of a Naturally Occurring Proline to Threonine Substitution within Acetolactate Synthase in Two Herbicide-Resistant Populations of Lactuca serriola,” Pesticide Biochemistry and Physiology, Vol. 84, No. 3, 2006, pp. 227-235. doi:10.1016/j.pestbp.2005.07.007
[23]	H. Chen, K. Saksa, F. Zhao, J. Qiu and L. Xiong “Genetic Analysis of Pathway Regulation for Enhancing Branched Chain Amino Acid Biosynthesis in Plants,” The Plant Journal, Vol. 63, No. 4, 2010, pp. 573-583. doi:10.1111/j.1365-313X.2010.04261.x
[24]	H. Saika, A. Oikawa, F. Matsuda, H. Onodera, K. Saito and S. Toki, “Application of Gene Targeting to Designed Mutation Breeding of High-Tryptophan Rice,” Plant Physiology, Vol. 156, No. 3, pp. 1269-1277. doi:10.1104/pp.111.175778
[25]	T. Shimizu, I. Nakayama, T. Nakao and H. Abe, “Partial Purification and Properties of Acetolactate Synthase and Etiolated Pea Seedlings,” Journal of Pesticide Science, Vol. 19, No. 3, 1994, pp. 187-196. doi:10.1584/jpestics.19.3_187
[26]	T. B. Ray, “Site of Action of Chlorsulfuron; Inhibition of Valine and Isoleucine Biosynthesis in Plants,” Plant Physiology, Vol. 75, No. 3, 1984, pp. 827-831. doi:10.1104/pp.75.3.827
[27]	H. Takahashi, M. Hayashi, F. Goto, S. Sato, S. Soga, T. Nishioka, M. Tomita, M. Kawai-Yamada and H. Uchimiya, “Evaluation of Metabolic Alteration in Transgenic Rice Overexpressing Dihydroflavonol-4-Reductase,” Annual of Botany, Vol. 98, No. 4, 2006, pp. 819-825. doi:10.1093/aob/mcl162
[28]	H. Takahashi, A. Watanabe, A. Tanaka, S.N. Hashida, M. Kawai-Yamada, K. Sonoike and H. Uchimiya, “Chloroplast NAD Kinase Is Essential for Energy Transduction through the Xanthophyll Cycle in Photosynthesis,” Plant Cell Physiology, Vol. 47, No. 12, 2006, pp. 1678-1682. doi:10.1093/pcp/pcl029