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Sukegawa S, Toki S, Saika H. Genome Editing Technology and Its Application to Metabolic Engineering in Rice. RICE (NEW YORK, N.Y.) 2022; 15:21. [PMID: 35366102 PMCID: PMC8976860 DOI: 10.1186/s12284-022-00566-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/18/2022] [Indexed: 05/18/2023]
Abstract
Genome editing technology can be used for gene engineering in many organisms. A target metabolite can be fortified by the knockout and modification of target genes encoding enzymes involved in catabolic and biosynthesis pathways, respectively, via genome editing technology. Genome editing is also applied to genes encoding proteins other than enzymes, such as chaperones and transporters. There are many reports of such metabolic engineering using genome editing technology in rice. Genome editing is used not only for site-directed mutagenesis such as the substitution of a single base in a target gene but also for random mutagenesis at a targeted region. The latter enables the creation of novel genetic alleles in a target gene. Recently, genome editing technology has been applied to random mutagenesis in a targeted gene and its promoter region in rice, enabling the screening of plants with a desirable trait from these mutants. Moreover, the expression level of a target gene can be artificially regulated by a combination of genome editing tools such as catalytically inactivated Cas protein with transcription activator or repressor. This approach could be useful for metabolic engineering, although expression cassettes for inactivated Cas fused to a transcriptional activator or repressor should be stably transformed into the rice genome. Thus, the rapid development of genome editing technology has been expanding the scope of molecular breeding including metabolic engineering. In this paper, we review the current status of genome editing technology and its application to metabolic engineering in rice.
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Affiliation(s)
- Satoru Sukegawa
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 Japan
| | - Seiichi Toki
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 Japan
- Graduate School of Nanobioscience, Yokohama City University, Yokohama, Kanagawa Japan
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Kanagawa Japan
- Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Shiga Japan
| | - Hiroaki Saika
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 Japan
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Takamura N, Yamazaki A, Sakuma N, Hirose S, Sakai M, Takani Y, Yamashita S, Oshima M, Kuroki M, Tozawa Y. Catalytic promiscuity of rice 2-oxoglutarate/Fe(II)-dependent dioxygenases supports xenobiotic metabolism. PLANT PHYSIOLOGY 2021; 187:816-828. [PMID: 34608958 PMCID: PMC8491036 DOI: 10.1093/plphys/kiab293] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/06/2021] [Indexed: 06/13/2023]
Abstract
The rice (Oryza sativa) 2-oxoglutarate (2OG)/Fe(II)-dependent dioxygenase HIS1 mediates the catalytic inactivation of five distinct β-triketone herbicides (bTHs). By assessing the effects of plant growth regulators on HIS1 enzyme function, we found that HIS1 mediates the hydroxylation of trinexapac-ethyl (TE) in the presence of Fe2+ and 2OG. TE blocks gibberellin biosynthesis, and we observed that its addition to culture medium induced growth retardation of rice seedlings in a concentration-dependent manner. Similar treatment with hydroxylated TE revealed that hydroxylation greatly attenuated the inhibitory effect of TE on plant growth. Forced expression of HIS1 in a rice his1 mutant also reduced its sensitivity to TE compared with that of the nontransformant. These results indicate that HIS1 metabolizes TE and thereby markedly reduces its ability to slow plant growth. Furthermore, analysis of five rice HIS1-like (HSL) proteins revealed that OsHSL2 and OsHSL4 also metabolize TE in vitro. HSLs from wheat (Triticum aestivum) and barley (Hordeum vulgare) also showed such activity. In contrast, OsHSL1, which shares the highest amino acid sequence identity with HIS1 and metabolizes the bTH tefuryltrione, did not manifest TE-metabolizing activity. Site-directed mutagenesis of OsHSL1 informed by structural models showed that substitution of three amino acids with the corresponding residues of HIS1 conferred TE-metabolizing activity similar to that of HIS1. Our results thus reveal a catalytic promiscuity of HIS1 and its related enzymes that support xenobiotic metabolism in plants.
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Affiliation(s)
- Natsuki Takamura
- Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan
| | - Akihiko Yamazaki
- Tsukuba Research & Technology Center, SDS Biotech K.K., Tsukuba, 300-2646, Japan
| | - Nozomi Sakuma
- Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan
| | - Sakiko Hirose
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, 305-8634, Japan
| | - Motonari Sakai
- Tsukuba Research & Technology Center, SDS Biotech K.K., Tsukuba, 300-2646, Japan
| | - Yukie Takani
- Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan
| | - Satoshi Yamashita
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, 920-1192, Japan
| | - Masahiro Oshima
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, 305-8634, Japan
| | - Makoto Kuroki
- Institute of Crop Science, National Agriculture and Food Research Organization, Tsukuba, 305-8518, Japan
| | - Yuzuru Tozawa
- Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan
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Suzuki K, Inoue H, Matsuoka S, Tero R, Hirano-Iwata A, Tozawa Y. Establishment of a cell-free translation system from rice callus extracts. Biosci Biotechnol Biochem 2020; 84:2028-2036. [PMID: 32543982 DOI: 10.1080/09168451.2020.1779024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Eukaryotic in vitro translation systems require large numbers of protein and RNA components and thereby rely on the use of cell extracts. Here we established a new in vitro translation system based on rice callus extract (RCE). We confirmed that RCE maintains its initial activity even after five freeze-thaw cycles and that the optimum temperature for translation is around 20°C. We demonstrated that the RCE system allows the synthesis of hERG, a large membrane protein, in the presence of liposomes. We also showed that the introduction of a bicistronic mRNA based on 2A peptide to RCE allowed the production of two distinct proteins from a single mRNA. Our new method thus facilitates laboratory-scale production of cell extracts, making it a useful tool for the in vitro synthesis of proteins for biochemical studies.
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Affiliation(s)
- Kakeru Suzuki
- Graduate School of Science and Engineering, Saitama University , Saitama, Japan
| | - Haruka Inoue
- Graduate School of Science and Engineering, Saitama University , Saitama, Japan
| | - Satoshi Matsuoka
- Graduate School of Science and Engineering, Saitama University , Saitama, Japan
| | - Ryugo Tero
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology , Toyohashi, Japan
| | - Ayumi Hirano-Iwata
- Advanced Institute for Materials Research, Tohoku University , Sendai, Japan
| | - Yuzuru Tozawa
- Graduate School of Science and Engineering, Saitama University , Saitama, Japan
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Maeda H, Murata K, Sakuma N, Takei S, Yamazaki A, Karim MR, Kawata M, Hirose S, Kawagishi-Kobayashi M, Taniguchi Y, Suzuki S, Sekino K, Ohshima M, Kato H, Yoshida H, Tozawa Y. A rice gene that confers broad-spectrum resistance to β-triketone herbicides. Science 2020; 365:393-396. [PMID: 31346065 DOI: 10.1126/science.aax0379] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 06/28/2019] [Indexed: 01/08/2023]
Abstract
The genetic variation of rice cultivars provides a resource for further varietal improvement through breeding. Some rice varieties are sensitive to benzobicyclon (BBC), a β-triketone herbicide that inhibits 4-hydroxyphenylpyruvate dioxygenase (HPPD). Here we identify a rice gene, HIS1 (HPPD INHIBITOR SENSITIVE 1), that confers resistance to BBC and other β-triketone herbicides. We show that HIS1 encodes an Fe(II)/2-oxoglutarate-dependent oxygenase that detoxifies β-triketone herbicides by catalyzing their hydroxylation. Genealogy analysis revealed that BBC-sensitive rice variants inherited a dysfunctional his1 allele from an indica rice variety. Forced expression of HIS1 in Arabidopsis conferred resistance not only to BBC but also to four additional β-triketone herbicides. HIS1 may prove useful for breeding herbicide-resistant crops.
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Affiliation(s)
- Hideo Maeda
- Institute of Crop Science, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8518, Japan
| | - Kazumasa Murata
- Toyama Prefectural Agricultural, Forestry and Fisheries Research Center, Toyama 939-8153, Japan
| | - Nozomi Sakuma
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Satomi Takei
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Akihiko Yamazaki
- Tsukuba Research and Technology Center, SDS Biotech K.K., Tsukuba 300-2646, Japan
| | - Md Rezaul Karim
- Institute of Crop Science, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8518, Japan
| | - Motoshige Kawata
- Institute of Agrobiological Sciences, NARO, Tsukuba 305-8634, Japan
| | - Sakiko Hirose
- Institute of Agrobiological Sciences, NARO, Tsukuba 305-8634, Japan
| | | | - Yojiro Taniguchi
- Institute of Agrobiological Sciences, NARO, Tsukuba 305-8634, Japan
| | - Satoru Suzuki
- Tsukuba Research and Technology Center, SDS Biotech K.K., Tsukuba 300-2646, Japan
| | - Keisuke Sekino
- Tsukuba Research and Technology Center, SDS Biotech K.K., Tsukuba 300-2646, Japan
| | - Masahiro Ohshima
- Institute of Agrobiological Sciences, NARO, Tsukuba 305-8634, Japan
| | - Hiroshi Kato
- Institute of Crop Science, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8518, Japan
| | - Hitoshi Yoshida
- Institute of Agrobiological Sciences, NARO, Tsukuba 305-8634, Japan
| | - Yuzuru Tozawa
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan.
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Wang PM, Choera T, Wiemann P, Pisithkul T, Amador-Noguez D, Keller NP. TrpE feedback mutants reveal roadblocks and conduits toward increasing secondary metabolism in Aspergillus fumigatus. Fungal Genet Biol 2015; 89:102-113. [PMID: 26701311 DOI: 10.1016/j.fgb.2015.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Revised: 11/23/2015] [Accepted: 12/05/2015] [Indexed: 12/11/2022]
Abstract
Small peptides formed from non-ribosomal peptide synthetases (NRPS) are bioactive molecules produced by many fungi including the genus Aspergillus. A subset of NRPS utilizes tryptophan and its precursor, the non-proteinogenic amino acid anthranilate, in synthesis of various metabolites such as Aspergillus fumigatus fumiquinazolines (Fqs) produced by the fmq gene cluster. The A. fumigatus genome contains two putative anthranilate synthases - a key enzyme in conversion of anthranilic acid to tryptophan - one beside the fmq cluster and one in a region of co-linearity with other Aspergillus spp. Only the gene found in the co-linear region, trpE, was involved in tryptophan biosynthesis. We found that site-specific mutations of the TrpE feedback domain resulted in significantly increased production of anthranilate, tryptophan, p-aminobenzoate and fumiquinazolines FqF and FqC. Supplementation with tryptophan restored metabolism to near wild type levels in the feedback mutants and suggested that synthesis of the tryptophan degradation product kynurenine could negatively impact Fq synthesis. The second putative anthranilate synthase gene next to the fmq cluster was termed icsA for its considerable identity to isochorismate synthases in bacteria. Although icsA had no impact on A. fumigatus Fq production, deletion and over-expression of icsA increased and decreased respectively aromatic amino acid levels suggesting that IcsA can draw from the cellular chorismate pool.
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Affiliation(s)
- Pin-Mei Wang
- Ocean College, Zhejiang University, Hangzhou 310058, Zhejiang Province, PR China
| | - Tsokyi Choera
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, USA
| | - Philipp Wiemann
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, USA
| | | | | | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, USA; Department of Bacteriology, University of Wisconsin, Madison, USA.
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Changes in primary and secondary metabolite levels in response to gene targeting-mediated site-directed mutagenesis of the anthranilate synthase gene in rice. Metabolites 2012; 2:1123-38. [PMID: 24957777 PMCID: PMC3901229 DOI: 10.3390/metabo2041123] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 12/04/2012] [Accepted: 12/09/2012] [Indexed: 11/17/2022] Open
Abstract
Gene targeting (GT) via homologous recombination allows precise modification of a target gene of interest. In a previous study, we successfully used GT to produce rice plants accumulating high levels of free tryptophan (Trp) in mature seeds and young leaves via targeted modification of a gene encoding anthranilate synthase-a key enzyme of Trp biosynthesis. Here, we performed metabolome analysis in the leaves and mature seeds of GT plants. Of 72 metabolites detected in both organs, a total of 13, including Trp, involved in amino acid metabolism, accumulated to levels >1.5-fold higher than controls in both leaves and mature seeds of GT plants. Surprisingly, the contents of certain metabolites valuable for both humans and livestock, such as γ-aminobutyric acid and vitamin B, were significantly increased in mature seeds of GT plants. Moreover, untargeted analysis using LC-MS revealed that secondary metabolites, including an indole alkaloid, 2-[2-hydroxy-3-β-d-glucopyranosyloxy-1-(1H-indol-3-yl)propyl] tryptophan, also accumulate to higher levels in GT plants. Some of these metabolite changes in plants produced via GT are similar to those observed in plants over expressing mutated genes, thus demonstrating that in vivo protein engineering via GT can be an effective approach to metabolic engineering in crops.
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Saika H, Oikawa A, Matsuda F, Onodera H, Saito K, Toki S. Application of gene targeting to designed mutation breeding of high-tryptophan rice. PLANT PHYSIOLOGY 2011; 156:1269-77. [PMID: 21543727 PMCID: PMC3135912 DOI: 10.1104/pp.111.175778] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 05/01/2011] [Indexed: 05/19/2023]
Abstract
Site-directed mutagenesis via gene targeting (GT) based on homologous recombination is the ultimate mutation breeding technology because it enables useful information acquired from structural- and computational-based protein engineering to be applied directly to molecular breeding, including metabolic engineering, of crops. Here, we employed this rationale to introduce precise mutations in OASA2--an α-subunit of anthranilate synthase that is a key enzyme of tryptophan (Trp) biosynthesis in rice (Oryza sativa)--via GT, with subsequent selection of GT cells using a Trp analog. The expression level of OASA2 in plants homozygous and heterozygous for modified OASA2 was similar to that of nontransformants, suggesting that OASA2 transcription in GT plants was controlled in the same manner as endogenous OASA2, and that GT could lead to a lower risk of gene silencing than in conventional overexpression approaches. Moreover, we showed that enzymatic properties deduced from protein engineering or in vitro analysis could be reproduced in GT plants as evidenced by Trp accumulation levels. Interestingly, mature seeds of homozygous GT plants accumulated Trp levels 230-fold higher than in nontransformants without any apparent morphological or developmental changes. Thus, we have succeeded in producing a novel rice plant of great potential nutritional benefit for both man and livestock that could not have been selected using conventional mutagenesis approaches. Our results demonstrate the effectiveness of directed crop improvement by combining precision mutagenesis via GT with a knowledge of protein engineering.
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Takai K, Sawasaki T, Endo Y. Chapter 2. Development of key technologies for high-throughput cell-free protein production with the extract from wheat embryos. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2011; 75:53-84. [PMID: 20731989 DOI: 10.1016/s0065-3233(07)75002-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
The cell-free translation system from wheat embryos had been considered to be inefficient as compared with the E. coli cell-based and cell-free protein production methods. However, it was revealed that the extract from extensively washed wheat embryo particles can provide a very productive cell-free protein synthesis system. Since then, the method has been improved, so that it fits the postgenomic researches. New mRNA configurations enabled us to synthesize many different proteins in parallel and to prepare large amounts of proteins, which fits the need for screening of suitable proteins for structural and functional analyses before large-scale production. The new reaction formats promoted the developments of new machines that perform highly parallel and highly productive protein synthesis reactions automatically. It was revealed that, by parallel synthesis of many proteins, much more multidomain proteins are produced in soluble forms in the wheat system than in the prokaryotic systems. The wheat system provides a rapid and cost-effective method for stable isotope labeling of proteins for NMR analyses. Selenomethionine substitution of proteins for X-ray crystallography through the cell-free synthesis was also achieved. Synthesis of some families of proteins that were difficult to be produced by conventional methods has been tested. At least, cytotoxic restriction enzymes were readily produced in a large amount. Some multisubunit proteins and cofactor-binding proteins could be synthesized by the method and were characterized successfully. Membrane proteins have also been tested, and a transporter was synthesized in an active form. Although some issues remains to be solved, we expect that the wheat cell-free protein synthesis system can contribute to the structural and functional genomics and to the future understanding of life.
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Affiliation(s)
- Kazuyuki Takai
- Cell-Free Science and Technology Research Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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Ohta T, Matsuoka H, Nomura Y, Tozawa Y. Control of translational initiation in the wheat-embryo cell-free protein expression system for producing homogenous products. Protein Expr Purif 2010; 73:15-22. [DOI: 10.1016/j.pep.2010.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 03/16/2010] [Accepted: 03/16/2010] [Indexed: 10/19/2022]
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Yamauchi S, Fusada N, Hayashi H, Utsumi T, Uozumi N, Endo Y, Tozawa Y. The consensus motif for N-myristoylation of plant proteins in a wheat germ cell-free translation system. FEBS J 2010; 277:3596-607. [DOI: 10.1111/j.1742-4658.2010.07768.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nishiyama Y, Yun CS, Matsuda F, Sasaki T, Saito K, Tozawa Y. Expression of bacterial tyrosine ammonia-lyase creates a novel p-coumaric acid pathway in the biosynthesis of phenylpropanoids in Arabidopsis. PLANTA 2010; 232:209-18. [PMID: 20396902 DOI: 10.1007/s00425-010-1166-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 03/31/2010] [Indexed: 05/09/2023]
Abstract
Some flavonoids are considered as beneficial compounds because they exhibit anticancer or antioxidant activity. In higher plants, flavonoids are secondary metabolites that are derived from phenylpropanoid biosynthetic pathway. A large number of phenylpropanoids are generated from p-coumaric acid, which is a derivative of the primary metabolite, phenylalanine. The first two steps in the phenylpropanoid biosynthetic pathway are catalyzed by phenylalanine ammonia-lyase and cinnamate 4-hydroxylase, and the coupling of these two enzymes forms a rate-limiting step in the pathway. For the generation of p-coumaric acid, the conversion from phenylalanine to p-coumaric acid that is catalyzed by two enzymes can be theoretically performed by a single enzyme, tyrosine ammonia-lyase (TAL) that catalyzes the conversion of tyrosine to p-coumaric acid in certain bacteria. To modify the p-coumaric acid pathway in plants, we isolated a gene encoding TAL from a photosynthetic bacterium, Rhodobacter sphaeroides, and introduced the gene (RsTAL) in Arabidopsis thaliana. Analysis of metabolites revealed that the ectopic over-expression of RsTAL leads to higher accumulation of anthocyanins in transgenic 5-day-old seedlings. On the other hand, 21-day-old seedlings of plants expressing RsTAL showed accumulation of higher amount of quercetin glycosides, sinapoyl and p-coumaroyl derivatives than control. These results indicate that ectopic expression of the RsTAL gene in Arabidopsis enhanced the metabolic flux into the phenylpropanoid pathway and resulted in increased accumulation of flavonoids and phenylpropanoids.
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Affiliation(s)
- Yasutaka Nishiyama
- Cell-Free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
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Abstract
Utilization of structural information from homologous proteins to design novel enzymes is one of the practical applications of structural biology. Structure-based protein engineering is a more reasonable strategy compared with general random mutagenesis. Here, we describe a useful method for production of a series of mutant enzymes based on a cell-free translation system. We employed PCR-mediated in vitro site-directed mutagenesis in combination with wheat-embryo cell-free protein synthesis to establish a high-throughput system. The efficient generation of a series of mutant enzymes facilitates high-throughput screening of functionally improved enzymes.
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Abstract
Biochemical characterization of each gene product encoded in the genome is essential to understand how cells are regulated. The bottleneck has been and still is in how the gene products can be obtained. The wheat cell-free protein synthesis system we have developed is a powerful method for preparation of many different proteins at a time and also for preparation of large amounts of specific proteins for biochemical and structural analyses. Here, we show a method for preparation of the wheat embryo extract useful for the cell-free reactions, by which 5 ml of a high-activity extract is obtained in 4-5 d. We also describe the methods for small- and large-scale protein synthesis by hands-down operations with the use of mRNAs prepared by transcription of PCR products and pEU plasmids harboring the target cDNAs, which need 2-4 d excepting the time required for plasmid preparation.
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Tozawa Y, Nozawa A, Kanno T, Narisawa T, Masuda S, Kasai K, Nanamiya H. Calcium-activated (p)ppGpp synthetase in chloroplasts of land plants. J Biol Chem 2007; 282:35536-45. [PMID: 17938177 DOI: 10.1074/jbc.m703820200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The genetic system of chloroplasts, including the machinery for transcription, translation, and DNA replication, exhibits substantial similarity to that of eubacteria. Chloroplasts are also thought to possess a system for generating guanosine 5'-triphosphate ((p)ppGpp), which triggers the stringent response in eubacteria, with genes encoding chloroplastic (p)ppGpp synthetase having been identified. We now describe the identification and characterization of genes (OsCRSH1, OsCRSH2, and OsCRSH3) for a novel type of (p)ppGpp synthetase in rice. The proteins encoded by these genes contain a putative chloroplast transit peptide at the NH(2) terminus, a central RelA-SpoT-like domain, and two EF-hand motifs at the COOH terminus. The recombinant OsCRSH1 protein was imported into chloroplasts in vitro, and genetic complementation analysis revealed that expression of OsCRSH1 suppressed the phenotype of an Escherichia coli mutant deficient in the RelA and SpoT enzymes. Biochemical analysis showed that the OsCRSH proteins possess (p)ppGpp synthetase activity that is dependent both on Ca(2+) and on the EF-hand motifs. A data base search identified a CRSH homolog in the dicotyledon Arabidopsis thaliana, indicating that such genes are conserved among both monocotyledonous and dicotyledonous land plants. CRSH proteins thus likely function as Ca(2+)-activated (p)ppGpp synthetases in plant chloroplasts, implicating both Ca(2+) and (p)ppGpp signaling in regulation of the genetic system of these organelles.
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Affiliation(s)
- Yuzuru Tozawa
- Cell-Free Science and Technology Research Center, Ehime University, Matsuyama, Japan.
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Kanno T, Kitano M, Kato R, Omori A, Endo Y, Tozawa Y. Sequence specificity and efficiency of protein N-terminal methionine elimination in wheat-embryo cell-free system. Protein Expr Purif 2006; 52:59-65. [PMID: 17123829 DOI: 10.1016/j.pep.2006.09.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Revised: 09/06/2006] [Accepted: 09/12/2006] [Indexed: 10/24/2022]
Abstract
Recent improvements in wheat-embryo cell-free translation resulted in a highly productive system for protein preparation. To clarify N-terminal processing of the cell-free system in a preparative-scale (> mg protein product per ml), 20 mutant variants of maltose-binding protein (MalE), each having a different penultimate residue in the sequence Met-Xaa-Ile-Glu-, and 20 glutathione S-transferase (GST) variants, having Met-Xaa-Pro-Ile-sequence, were designed and synthesized. The MalE and GST proteins were purified by amylose-resin and glutathione columns, respectively, followed by analysis of their N-terminal sequences. These investigations revealed that sequence specificity and efficiency of the N-terminal Met (N-Met) elimination in the cell-free system are similar to those reported from investigations in cellular systems or in the wheat-embryo cell-free protein expression system in analytical scale (approximately 10 microg protein product per ml). Cleavage of the N-Met is basically determined by the penultimate amino acid in the polypeptide sequence. In the case of MalE, the cleavage was efficient when the penultimate residue was Ala, Cys, Gly, Pro, Ser or Thr. But, in the case of GST with Pro as the antepenultimate residue, the efficiency was significantly reduced when the penultimate residue was Gly or Thr. We also confirmed that substitution of the antepenultimate residue in MalE to Pro drastically reduced the efficiency of N-Met cleavage when the penultimate residue was Ala, Gly, Pro, Ser or Thr, indicating inhibitory effects of antepenultimate residue Pro on N-Met elimination. These results clarified sequence-specific functions of the endogenous N-terminal processing machinery in the scaled-up wheat-embryo cell-free translation system.
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Affiliation(s)
- Takuya Kanno
- Cell-Free Science and Technology Research Center, Ehime University, Matsuyama 790-8577, Japan
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