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Genome-Wide Analysis of Genes Encoding Methionine-Rich Proteins in Arabidopsis and Soybean Suggesting Their Roles in the Adaptation of Plants to Abiotic Stress. Int J Genomics 2016; 2016:5427062. [PMID: 27635394 PMCID: PMC5007304 DOI: 10.1155/2016/5427062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 07/19/2016] [Indexed: 11/30/2022] Open
Abstract
Oxidation and reduction of methionine (Met) play important roles in scavenging reactive oxygen species (ROS) and signaling in living organisms. To understand the impacts of Met oxidation and reduction in plants during stress, we surveyed the genomes of Arabidopsis and soybean (Glycine max L.) for genes encoding Met-rich proteins (MRPs). We found 121 and 213 genes encoding MRPs in Arabidopsis and soybean, respectively. Gene annotation indicated that those with known function are involved in vital cellular processes such as transcriptional control, calcium signaling, protein modification, and metal transport. Next, we analyzed the transcript levels of MRP-coding genes under normal and stress conditions. We found that 57 AtMRPs were responsive either to drought or to high salinity stress in Arabidopsis; 35 GmMRPs were responsive to drought in the leaf of late vegetative or early reproductive stages of soybean. Among the MRP genes with a known function, the majority of the abiotic stress-responsive genes are involved in transcription control and calcium signaling. Finally, Arabidopsis plant which overexpressed an MRP-coding gene, whose transcripts were downregulated by abiotic stress, was more sensitive to paraquat than the control. Taken together, our report indicates that MRPs participate in various vital processes of plants under normal and stress conditions.
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Generation of branched-chain amino acids resistant Corynebacterium glutamicum acetohydroxy acid synthase by site-directed mutagenesis. BIOTECHNOL BIOPROC E 2014. [DOI: 10.1007/s12257-013-0843-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hong SH, Nam HK, Kim KR, Kim SW, Oh DK. Molecular characterization of an aldo-keto reductase from Marivirga tractuosa that converts retinal to retinol. J Biotechnol 2014; 169:23-33. [DOI: 10.1016/j.jbiotec.2013.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 10/10/2013] [Accepted: 11/11/2013] [Indexed: 01/20/2023]
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Kishchenko EM, Komarnitskii IK, Kuchuk NV. Transgenic sugar beet tolerant to imidazolinone obtained by Agrobacterium-mediated transformation. CYTOL GENET+ 2011. [DOI: 10.3103/s0095452711030030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yoon MY, Gedi V, Kim J, Park Y, Kim DE, Park EH, Choi JD. Structural and functional evaluation of three well-conserved serine residues in tobacco acetohydroxyacid synthase. Biochimie 2010; 92:65-70. [PMID: 19825392 DOI: 10.1016/j.biochi.2009.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 09/21/2009] [Indexed: 11/19/2022]
Abstract
The first step in the common pathway for the biosynthesis of branched-chain amino acids (BCAAs) is catalyzed by acetohydroxyacid synthase (AHAS). The roles of three well-conserved serine residues (S167, S506, and S539) in tobacco AHAS were determined using site-directed mutagenesis. The mutations S167F and S506F were found to be inactive and abolished the binding affinity for cofactor FAD. The Far-UV CD spectrum of the inactive mutants was similar to that of wild-type enzyme, indicating no major conformational changes in the secondary structure. However, the active mutants, S167R, S506A, S506R, S539A, S539F and S539R, showed lower specific activities. Further, a homology model of tobacco AHAS was generated based on the crystal structure of yeast AHAS. In the model, the S167 and S506 residues were identified near the FAD binding site, while the S539 residue was found to near the ThDP binding site. The S539 mutants, S539A and S539R, showed strong resistance to three classes of herbicides, NC-311 (a sulfonylurea), Cadre (an imidazolinone), and TP (a triazolopyrimidine). In contrast, the active S167 and S506 mutants did not show any significant resistance to the herbicides, with the exception of S506R, which showed strong resistance to all herbicides. Thus, our results suggest that the S167 and S506 residues are essential for catalytic activity by playing a role in the FAD binding site. The S539 residue was found to be near the ThDP with an essential role in the catalytic activity and specific mutants of this residue (S539A and S539R) showed strong herbicide resistance as well.
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Affiliation(s)
- Moon-Young Yoon
- Department of Chemistry, Hanyang University, Seoul, Republic of Korea.
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Structure and Functional Effect of Tryptophan Mutants of Nicotiana tabacum Acetohydroxyacid Synthase. B KOREAN CHEM SOC 2008. [DOI: 10.5012/bkcs.2008.29.9.1823] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Duggleby RG, McCourt JA, Guddat LW. Structure and mechanism of inhibition of plant acetohydroxyacid synthase. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:309-24. [PMID: 18234503 DOI: 10.1016/j.plaphy.2007.12.004] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Indexed: 05/04/2023]
Abstract
Plants and microorganisms synthesize valine, leucine and isoleucine via a common pathway in which the first reaction is catalysed by acetohydroxyacid synthase (AHAS, EC 2.2.1.6). This enzyme is of substantial importance because it is the target of several herbicides, including all members of the popular sulfonylurea and imidazolinone families. However, the emergence of resistant weeds due to mutations that interfere with the inhibition of AHAS is now a worldwide problem. Here we summarize recent ideas on the way in which these herbicides inhibit the enzyme, based on the 3D structure of Arabidopsis thaliana AHAS. This structure also reveals important clues for understanding how various mutations can lead to herbicide resistance.
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Affiliation(s)
- Ronald G Duggleby
- RDBiotech, 22 Parklands Boulevard, Little Mountain, Queensland 4551, Australia.
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Virtual Screening of Tubercular Acetohydroxy Acid Synthase Inhibitors through Analysis of Structural Models. B KOREAN CHEM SOC 2007. [DOI: 10.5012/bkcs.2007.28.6.947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Le DT, Yoon MY, Kim YT, Choi JD. Roles of three well-conserved arginine residues in mediating the catalytic activity of tobacco acetohydroxy acid synthase. J Biochem 2005; 138:35-40. [PMID: 16046446 DOI: 10.1093/jb/mvi099] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Acetohydroxy acid synthase (AHAS, EC 2.2.1.6; also known as acetolactate synthase, ALS) catalyzes the first common step in the biosynthesis of valine, leucine, and isoleucine in plants and microorganisms. AHAS is the target of several classes of herbicides. In the present study, the role of three well-conserved arginine residues (R141, R372, and R376) in tobacco AHAS was determined by site-directed mutagenesis. The mutated enzymes, referred to as R141A, R141F, and R376F, were inactive and unable to bind to the cofactor, FAD. The inactive mutants had the same secondary structure as that of the wild type. The mutants R141K, R372F, and R376K exhibited much lower specific activities than the wild type, and moderate resistance to herbicides such as Londax, Cadre, and/or TP. The mutation R141K showed a strong reduction in activation efficiency by ThDP, while the mutations R372K and R376K showed a strong reductions in activation efficiency by FAD in comparison to the wild type enzyme. Taking into account the data presented here and the homology model constructed previously [Le et al. (2004) Biochem. Biophys. Res. Commun. 317, 930-938], it is suggested that the three amino acid residues studied (R141, R372, and R376) are located essentially at the enzyme active site, and, furthermore, that residues R372 and R376 are possibly responsible for the binding of the enzyme to FAD.
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Affiliation(s)
- Dung Tien Le
- School of Life Sciences, Chungbuk National University, Cheongju 361-763, Korea
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Le DT, Yoon MY, Tae Kim Y, Choi JD. Two consecutive aspartic acid residues conferring herbicide resistance in tobacco acetohydroxy acid synthase. BIOCHIMICA ET BIOPHYSICA ACTA 2005; 1749:103-12. [PMID: 15848141 DOI: 10.1016/j.bbapap.2005.02.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 02/22/2005] [Accepted: 02/24/2005] [Indexed: 10/25/2022]
Abstract
Acetohydroxy acid synthase (AHAS) catalyzes the first common step in the biosynthesis pathway of the branch chain amino acids in plants and microorganisms. A great deal of interest has been focused on AHAS since it was identified as the target of several classes of potent herbicides. In an effort to produce a mutant usable in the development of an herbicide-resistant transgenic plant, two consecutive aspartic acid residues, which are very likely positioned next to the enzyme-bound herbicide sulfonylurea as the homologous residues in AHAS from yeast, were selected for this study. Four single-point mutants and two double mutants were constructed, and designated D374A, D374E, D375A, D375E, D374A/D375A, and D374E/D375E. All mutants were active, but the D374A mutant exhibited substrate inhibition at high concentrations. The D374E mutant also evidenced a profound reduction with regard to catalytic efficiency. The mutation of D375A increased the K(m) value for pyruvate nearly 10-fold. In contrast, the D375E mutant reduced this value by more than 3-fold. The double mutants exhibited synergistic reduction in catalytic efficiencies. All mutants constructed in this study proved to be strongly resistant to the herbicide sulfonylurea Londax. The double mutants and the mutants with the D375 residue were also strongly cross-resistant to the herbicide triazolopyrimidine TP. However, only the D374A mutant proved to be strongly resistant to imidazolinone Cadre. The data presented here indicate that the two residues, D374 and D375, are located at a common binding site for the herbicides sulfonylurea and triazolopyrimidine. D375E may be a valuable mutant for the development of herbicide-resistant transgenic plants.
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Affiliation(s)
- Dung Tien Le
- School of Life Sciences, Chungbuk National University, Cheongju 361-763, South Korea
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Jung SM, Le D, Yoon SS, Yoon MY, Kim Y, Choi JD. Amino acid residues conferring herbicide resistance in tobacco acetohydroxy acid synthase. Biochem J 2004; 383:53-61. [PMID: 15214847 PMCID: PMC1134043 DOI: 10.1042/bj20040720] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 06/04/2004] [Accepted: 06/24/2004] [Indexed: 11/17/2022]
Abstract
The enzyme AHAS (acetohydroxy acid synthase), which is involved in the biosynthesis of valine, leucine and isoleucine, is the target of several classes of herbicides. A model of tobacco AHAS was generated based on the X-ray structure of yeast AHAS. Well conserved residues at the herbicide-binding site were identified, and the roles of three of these residues (Phe-205, Val-570 and Phe-577) were determined by site-directed mutagenesis. The Phe-205 mutants F205A, F205H, F205W and F205Y showed markedly decreased levels of catalytic efficiency, and cross-resistance to two or three classes of herbicides, i.e. Londax (a sulphonylurea herbicide), Cadre (an imidazolinone herbicide) and TP (a triazolopyrimidine derivative). None of the mutations caused significant changes in the secondary or tertiary structure of the enzyme. Four mutants of Phe-577, i.e. F577D, F577E, F577K and F577R, showed unaltered V(max) values, but substantially decreased catalytic efficiency. However, these mutants were highly resistant to two or three of the tested herbicides. The three mutants F577D, F577E and F577R had a similar secondary structure to that of wild-type AHAS. Conservative mutations of Phe-577, i.e. F577W and F577Y, did not affect the kinetic properties of the enzyme or its inhibition by herbicides. The mutation Val-570 to Asn abolished the binding affinity of the enzyme for FAD as well as its activity, and also caused a change in the tertiary structure of AHAS. However, the mutant V570Q was active, but resistant to two classes of herbicides, i.e. Londax and TP. The conservative mutant V570I was substantially reduced in catalytic efficiency and moderately resistant to the three herbicides. The results of this study suggest that residues Phe-205, Val-570 and Phe-577 in tobacco AHAS are located at or near the binding site that is common for the three classes of herbicides. In addition, Phe-205 and Val-570 are probably located at the herbicide-binding site that may overlap partially with the active site. Selected mutants of Phe-577 are expected to be utilized to construct herbicide-resistant transgenic plants.
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Affiliation(s)
- Sun-Mi Jung
- *School of Life Sciences and Biotechnology Research Institute, Chungbuk National University, Cheongju 361-763, Korea
| | - Dung Tien Le
- *School of Life Sciences and Biotechnology Research Institute, Chungbuk National University, Cheongju 361-763, Korea
| | - Sung-Sook Yoon
- *School of Life Sciences and Biotechnology Research Institute, Chungbuk National University, Cheongju 361-763, Korea
| | - Moon-Young Yoon
- †Department of Chemistry, Hanyang University, Seoul 133-791, Korea
| | - Young Tae Kim
- ‡Department of Microbiology, Pukyong National University, Busan 608-737, Korea
| | - Jung-Do Choi
- *School of Life Sciences and Biotechnology Research Institute, Chungbuk National University, Cheongju 361-763, Korea
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Le DT, Yoon MY, Kim YT, Choi JD. Homology modeling of the structure of tobacco acetohydroxy acid synthase and examination of the active site by site-directed mutagenesis. Biochem Biophys Res Commun 2004; 317:930-8. [PMID: 15081429 DOI: 10.1016/j.bbrc.2004.03.133] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2004] [Indexed: 11/24/2022]
Abstract
A reliable model of tobacco acetohydroxy acid synthase (AHAS) was obtained by homology modeling based on a yeast AHAS X-ray structure using the Swiss-Model server. Conserved residues at the dimer interface were identified, of which the functional roles of four residues, namely H142, E143, M489, and M542, were determined by site-directed mutagenesis. Eight mutants were successfully generated and purified, five of which (H142T, M489V, M542C, M542I, and M542V) were found to be inactive under various assay conditions. The H142K mutant was moderately altered in all kinetic parameters to a similar extent. In addition, the mutant was more thermo-labile than wild type enzyme. The E143A mutant increased the Km value more than 20-fold while other parameters were not significantly changed. All mutations carried out on residue M542 inactivated the enzyme. Though showing a single band on SDS-PAGE, the M542C mutant lost its native tertiary structure and was aggregated. Except M542C, each of the other mutants showed a secondary structure similar to that of wild type enzyme. Although all the inactive mutants were able to bind FAD, the mutants M489V and M542C showed a very low affinity for FAD. None of the active mutants constructed was strongly resistant to three tested herbicides. Taken together, the results suggest that the residues of H142, E143, M489, and M542 are essential for catalytic activity. Furthermore, it seems that H142 residue is involved in stabilizing the dimer interaction, while E143 residue may be involved in binding with substrate pyruvate. The data from the site-directed mutagenesis imply that the constructed homology model of tobacco AHAS is realistic.
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Affiliation(s)
- Dung Tien Le
- School of Life Sciences, Chungbuk National University, Cheongju 361-763, Republic of Korea
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