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Oku H, Mutanda I, Inafuku M. Molecular characteristics of isoprene synthase and its control effects on isoprene emissions from tropical trees. JOURNAL OF PLANT RESEARCH 2023; 136:63-82. [PMID: 36367585 DOI: 10.1007/s10265-022-01418-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
The isoprene emission rate from plants is simulated by a function of light intensity and leaf temperature, and the G-93 formula is the most extensively applied algorithm for this purpose. Isoprene is biosynthesized by the enzyme isoprene synthase (IspS), and instantly emitted from the leaf. Enzyme kinetics of IspS and substrate availability are important factors involved in the short-term leaf-level control of isoprene emissions. It is thus assumed that the parameters of G-93 may correlate with the kinetics of IspSs, however, at present there is no data available on the relationship between these two parameters. In this investigation, six IspS genes from tropical trees were cloned, their properties characterized, and the relationship between the enzyme kinetics of IspSs and the parameters of G-93 examined. There was a negative correlation between the enzyme kinetics of IspS Km and parameter CT1 of G93, which is used to define the temperature dependency of isoprene emissions. However, performance constant of IspS (kcat/Km) only showed slight positive correlation with CT1.suggesting that the enzyme kinetics of IspS has limited significance in controlling the temperature response of isoprene emissions. The molecular structure of IspS was further elucidated using a molecular dynamics simulation with a focus on the active site in the 6 α-helices bundle. The simulation of the enzyme-substrate complex of IspS from B. variegata predicted a new metal binding domain in helix F (E383) and catalytic motif FXRDRLXE in the A-C loop that could involve the deprotonation of dimethylallyl diphosphate (DMADP) to form a carbocation. Notably, after the binding of a metal ion and DMADP, the active-site closure mechanism was found to involve conformational alterations in the helix H-α1 and transition from a loose to tight enclosure of the 6 α-helices bundles to tune the active pocket size. The characteristics identified for the IspSs from tropical trees could help to explain regional isoprene emissions in tropical areas.
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Affiliation(s)
- Hirosuke Oku
- Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa, Japan.
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.
| | - Ishmael Mutanda
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Masashi Inafuku
- Faculty of Agriculture, University of the Ryukyus, Nishihara, Okinawa, Japan
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Oogai S, Fukuta M, Inafuku M, Oku H. Isolation and characterization of mimosine degrading enzyme from Arthrobacter sp. Ryudai-S1. World J Microbiol Biotechnol 2022; 38:172. [PMID: 35908235 DOI: 10.1007/s11274-022-03344-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 06/21/2022] [Indexed: 11/29/2022]
Abstract
Leucaena leucocephala growing in the tropics and subtropics serves as potential forage for livestock because its foliage is rich in protein, fiber, and minerals. However, its use for livestock feed has been hindered by toxic nonprotein amino acid mimosine. Therefore, it is necessary to develop a method to reduce or eliminate mimosine from foliage. A previous study found that the fermentation of L. leucocephala foliage reduced the mimosine content and prompted the authors to isolate potent mimosine degrading microorganisms and characterize the mimosinase for the complete elimination of mimosine in the L. leucocephala foliage. The soil screening of the L. leucocephala tree surroundings led to the isolation of Arthrobacter sp. Ryudai-S1, which can degrade and assimilate mimosine as a nitrogen and carbon source. Mimosinase in this strain was found to be thermostable and showed strong activity. Docking model's inspection and the interaction energy calculation between mimosine-pyridoxal-5'-phosphate (PLP) complex and the active site of this enzyme identified 11 important amino acid residues that stabilized the binding. Of these amino acid residues, mutation experiment suggested that Tyr-263' and Phe-34 stabilizes the substrate binding and play a critical role in guiding the substrate to proper positions to accomplish high catalytic efficacy and selectivity. These observations suggest that Arthrobacter sp. Ryudai-S1 could be potentially useful for the development of L. leucocephala feed with reduced mimosine content.
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Affiliation(s)
- Shigeki Oogai
- The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24, Ko-rimoto, Kagoshima, 890-8580, Japan
| | - Masakazu Fukuta
- The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24, Ko-rimoto, Kagoshima, 890-8580, Japan.,Faculty of Agriculture, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami-gun, Okinawa, 903-0213, Japan
| | - Masashi Inafuku
- Faculty of Agriculture, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami-gun, Okinawa, 903-0213, Japan
| | - Hirosuke Oku
- The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24, Ko-rimoto, Kagoshima, 890-8580, Japan. .,Molecular Biotechnology Group, Center of Molecular Bioscience, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Nakagami-gun, Okinawa, 903-0213, Japan.
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Wang Z, He F, Mu Y, Zhang L, Liu Z, Liu D, Yang J, Jin Z, Pei Y. Identification and functional characterization of a cystathionine β-lyase (CBL) enzyme for H 2S production in Arabidopsis thaliana. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 182:76-89. [PMID: 35472754 DOI: 10.1016/j.plaphy.2022.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/02/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
Sulfide or sulfur metabolism plays an important role in the growth and development of plants. Cystathionine β-lyase (CBL) is an important enzyme in methionine synthesis, but a comprehensive understanding of CBL functions is limited. As the third gasotransmitter, hydrogen sulfide (H2S) plays important physiological roles in plants. In this study, we found that the endogenous H2S content in Arabidopsis thaliana cbl mutants was lower than that in the wild type. Under PEG-based osmotic stress conditions, the H2S contents of CBL-overexpression (OE-CBL) plants increased significantly compared with the wild type. Additionally, the OE-CBL plants increased their tolerance to osmotic stress by increasing the transcription levels of drought-related genes and their relative water-loss rates. Compared with cbl and wild type, OE-CBL plants resisted drought stress by significantly closing their stomata, resulting in improved survival rates. Root tip-bending experiments showed that CBL overexpression relieved osmotic, heavy metal and cold stresses in Arabidopsis. The recombinant CBL activity in vitro revealed that CBL produced H2S using L-cysteine as a substrate. Thus, CBL had a very strong cysteine desulfhydrase activity that could produce endogenous H2S using L-cysteine as a substrate, and it played an important role in plant abiotic stress resistance.
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Affiliation(s)
- Zhiqing Wang
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Feng He
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, Shanxi Province, 030006, China; The Affiliated High School of Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Yao Mu
- Institute of Space Information, Space Engineering University, Beijing, 101416, China
| | - Liping Zhang
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Zhiqiang Liu
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Danmei Liu
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Jinbao Yang
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Zhuping Jin
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, Shanxi Province, 030006, China.
| | - Yanxi Pei
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, Shanxi Province, 030006, China.
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Biochemistry of plants N-heterocyclic non-protein amino acids. Amino Acids 2021; 53:801-812. [PMID: 33950299 DOI: 10.1007/s00726-021-02990-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/21/2021] [Indexed: 10/21/2022]
Abstract
Plants catalyze the biosynthesis of a large number of non-protein amino acids, which are usually toxic for other organisms. In this review, the chemistry and metabolism of N-heterocyclic non-protein amino acids from plants are described. These N-heterocyclic non-protein amino acids are composed of β-substituted alanines and include mimosine, β-pyrazol-1-yl-L-alanine, willardiine, isowillardiine, and lathyrine. These β-substituted alanines consisted of an N-heterocyclic moiety and an alanyl side chain. This review explains how these individual moieties are derived from their precursors and how they are used as the substrate for biosynthesizing the respective N-heterocyclic non-protein amino acids. In addition, known catabolism and possible role of these non-protein amino acids in the actual host is explained.
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