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Mishra A, Chakraborty S, Jaiswal TP, Bhattacharjee S, Kesarwani S, Mishra AK, Singh SS. Untangling the adaptive strategies of thermophilic bacterium Anoxybacillus rupiensis TPH1 under low temperature. Extremophiles 2024; 28:31. [PMID: 39020126 DOI: 10.1007/s00792-024-01346-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 06/10/2024] [Indexed: 07/19/2024]
Abstract
The present study investigates the low temperature tolerance strategies of thermophilic bacterium Anoxybacillus rupiensis TPH1, which grows optimally at 55 °C , by subjecting it to a temperature down-shift of 10 °C (45 °C) for 4 and 6 h followed by studying its growth, morphophysiological, molecular and proteomic responses. Results suggested that although TPH1 experienced increased growth inhibition, ROS production, protein oxidation and membrane disruption after 4 h of incubation at 45 °C yet maintained its DNA integrity and cellular structure through the increased expression of DNA damage repair and cell envelop synthesizing proteins and also progressively alleviated growth inhibition by 20% within two hours i.e., 6 h, by inducing the expression of antioxidative enzymes, production of unsaturated fatty acids, capsular and released exopolysaccharides and forming biofilm along with chemotaxis proteins. Conclusively, the adaptation of Anoxybacillus rupiensis TPH1 to lower temperature is mainly mediated by the synthesis of large numbers of defense proteins and exopolysaccharide rich biofilm formation.
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Affiliation(s)
- Aditi Mishra
- Laboratory of Cyanobacterial Systematics and Stress Biology, Department of Botany, Banaras Hindu University, Varanasi, India
| | - Sindhunath Chakraborty
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, India
| | - Tameshwar Prasad Jaiswal
- Laboratory of Cyanobacterial Systematics and Stress Biology, Department of Botany, Banaras Hindu University, Varanasi, India
| | - Samujjal Bhattacharjee
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, India
| | - Shreya Kesarwani
- Laboratory of Cyanobacterial Systematics and Stress Biology, Department of Botany, Banaras Hindu University, Varanasi, India
| | - Arun Kumar Mishra
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, India
| | - Satya Shila Singh
- Laboratory of Cyanobacterial Systematics and Stress Biology, Department of Botany, Banaras Hindu University, Varanasi, India.
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High pH Alleviated Sweet Orange ( Citrus sinensis) Copper Toxicity by Enhancing the Capacity to Maintain a Balance between Formation and Removal of Reactive Oxygen Species and Methylglyoxal in Leaves and Roots. Int J Mol Sci 2022; 23:ijms232213896. [PMID: 36430374 PMCID: PMC9698688 DOI: 10.3390/ijms232213896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
The contribution of reactive oxygen species (ROS) and methylglyoxal (MG) formation and removal in high-pH-mediated alleviation of plant copper (Cu)-toxicity remains to be elucidated. Seedlings of sweet orange (Citrus sinensis) were treated with 0.5 (non-Cu-toxicity) or 300 (Cu-toxicity) μM CuCl2 × pH 4.8, 4.0, or 3.0 for 17 weeks. Thereafter, superoxide anion production rate; H2O2 production rate; the concentrations of MG, malondialdehyde (MDA), and antioxidant metabolites (reduced glutathione, ascorbate, phytochelatins, metallothioneins, total non-protein thiols); and the activities of enzymes (antioxidant enzymes, glyoxalases, and sulfur metabolism-related enzymes) in leaves and roots were determined. High pH mitigated oxidative damage in Cu-toxic leaves and roots, thereby conferring sweet orange Cu tolerance. The alleviation of oxidative damage involved enhanced ability to maintain the balance between ROS and MG formation and removal through the downregulation of ROS and MG formation and the coordinated actions of ROS and MG detoxification systems. Low pH (pH 3.0) impaired the balance between ROS and MG formation and removal, thereby causing oxidative damage in Cu-toxic leaves and roots but not in non-Cu-toxic ones. Cu toxicity and low pH had obvious synergistic impacts on ROS and MG generation and removal in leaves and roots. Additionally, 21 (4) parameters in leaves were positively (negatively) related to the corresponding root parameters, implying that there were some similarities and differences in the responses of ROS and MG metabolisms to Cu-pH interactions between leaves and roots.
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Emri T, Gila B, Antal K, Fekete F, Moon H, Yu JH, Pócsi I. AtfA-Independent Adaptation to the Toxic Heavy Metal Cadmium in Aspergillus nidulans. Microorganisms 2021; 9:microorganisms9071433. [PMID: 34361869 PMCID: PMC8307709 DOI: 10.3390/microorganisms9071433] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 06/28/2021] [Accepted: 06/30/2021] [Indexed: 12/13/2022] Open
Abstract
Cadmium is an exceptionally toxic industrial and environmental pollutant classified as a human carcinogen. In order to provide insight into how we can keep our environment safe from cadmium contamination and prevent the accumulation of it in the food chain, we aim to elucidate how Aspergillus nidulans, one of the most abundant fungi in soil, survives and handles cadmium stress. As AtfA is the main transcription factor governing stress responses in A. nidulans, we examined genome-wide expression responses of wild-type and the atfA null mutant exposed to CdCl2. Both strains showed up-regulation of the crpA Cu2+/Cd2+ pump gene and AN7729 predicted to encode a putative bis(glutathionato)-cadmium transporter, and transcriptional changes associated with elevated intracellular Cys availability leading to the efficient adaptation to Cd2+. Although the deletion of atfA did not alter the cadmium tolerance of the fungus, the cadmium stress response of the mutant differed from that of a reference strain. Promoter and transcriptional analyses of the “Phospho-relay response regulator” genes suggest that the AtfA-dependent regulation of these genes can be relevant in this phenomenon. We concluded that the regulatory network of A. nidulans has a high flexibility allowing the fungus to adapt efficiently to stress both in the presence and absence of this important transcription factor.
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Affiliation(s)
- Tamás Emri
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
- Correspondence:
| | - Barnabás Gila
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
- Doctoral School of Nutrition and Food Sciences, University of Debrecen, 4032 Debrecen, Hungary
| | - Károly Antal
- Department of Zoology, Eszterházy Károly University, 3300 Eger, Hungary;
| | - Fanni Fekete
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
| | - Heungyun Moon
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; (H.M.); (J.-H.Y.)
| | - Jae-Hyuk Yu
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; (H.M.); (J.-H.Y.)
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
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Song Y, Wang L, Liu F, Jiao C, Nan H, Shen X, Chen H, Li Y, Lei B, Jiang J, Chen P, Xu Q. β-Cyanoalanine Synthase Regulates the Accumulation of β-ODAP via Interaction with Serine Acetyltransferase in Lathyrus sativus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:1953-1962. [PMID: 33538593 DOI: 10.1021/acs.jafc.0c07542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
β-N-Oxalyl-l-α,β-diaminopropionic acid (β-ODAP), found in Lathyrus sativus at first, causes a neurological disease, lathyrism, when over ingested in an unbalanced diet. Our previous research suggested that β-ODAP biosynthesis is related to sulfur metabolism. In this study, β-cyanoalanine synthase (β-CAS) was confirmed to be responsible for β-ODAP biosynthesis via in vitro enzymatic analysis. LsCAS was found to be pyridoxal phosphate (PLP)-dependent via spectroscopic analysis and dual functional via enzymatic activity analysis. Generation of a M135T/M235S/S239T triple mutant of LsCAS, which are the key sites to control the ratio of CAS/cysteine synthase (CS) activity, switches reaction chemistry to that of a CS. LsCAS interactions were further screened and verified via Y2H, BiFC and pull-down assay. It was suggested that LsSAT2 interacts and forms a cysteine regulatory complex (CRC) with LsCAS in mitochondria, which improves LsSAT while reduces LsCAS activities to affect β-ODAP content positively. These results provide new insights into the molecular regulation of β-ODAP content in L. sativus.
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Affiliation(s)
- Yaoyao Song
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Lei Wang
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, China
| | - Fengjuan Liu
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Chengjin Jiao
- College of Bioengineering and Biotechnology, Tianshui Normal University, Tianshui 741000, Gansu, China
| | - Hao Nan
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Xiao Shen
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Hong Chen
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Yifan Li
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Beilei Lei
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Jinglong Jiang
- School of Biological Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, Shaanxi, China
| | - Peng Chen
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Quanle Xu
- College of Life Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
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Ding Z, Fang Q, Daraz U, Sun Q. Physiological responses and metal distributions of different organs of Phragmites australis shoots under acid mine drainage stress. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:3375-3385. [PMID: 32918262 DOI: 10.1007/s11356-020-10700-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Phragmites australis, which is widely distributed throughout the world, is often used in the phytoremediation of acid mine drainage (AMD) due to its various mechanisms for survival under extremely harsh conditions. To explore the different responses of different aerial organs of P. australis to stress, soil and plant samples were collected from the AMD-polluted area of the Tongling mining area. The contents of manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and lead (Pb) in the soil and the leaf blades, leaf sheaths, and stems of P. australis as well as the contents/activities of cysteine synthase (CSase), superoxide dismutase (SOD), peroxidase (POD), glutathione (GSH), malondialdehyde (MDA), and proline (Pro) in the organs were determined. Our results revealed that the leaf sheath had the highest potential to store metals of all the organs. The highest translocation factor (TF) for Fe was observed from the stems to the leaf sheaths. A higher bioconcentration factor (BCF) for Mn was found in the leaf blades and leaf sheaths, while higher BCFs for Cd and Zn were observed in the stems. The content/activity of enzymatic and non-enzymatic stress-resistance substances varied from organ to organ. In general, the leaf sheaths remained almost as or slightly less stress-resistant than the leaf blades. It can be concluded that different plant organs play different roles in stress resistance, and understanding the tolerance mechanism of leaf sheaths to metals is essential for the application of phytoremediation procedures.
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Affiliation(s)
- Ziwei Ding
- School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China
- Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
- Mining environmental restoration and wetland ecological security Collaborative Innovation Center, Hefei, China
| | - Qing Fang
- School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China
- Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
- Mining environmental restoration and wetland ecological security Collaborative Innovation Center, Hefei, China
| | - Umar Daraz
- School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China
- Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
- Mining environmental restoration and wetland ecological security Collaborative Innovation Center, Hefei, China
| | - Qingye Sun
- School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China.
- Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China.
- Mining environmental restoration and wetland ecological security Collaborative Innovation Center, Hefei, China.
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Impact of Classical Strain Improvement of Penicillium rubens on Amino Acid Metabolism during β-Lactam Production. Appl Environ Microbiol 2020; 86:AEM.01561-19. [PMID: 31757830 DOI: 10.1128/aem.01561-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/16/2019] [Indexed: 11/20/2022] Open
Abstract
To produce high levels of β-lactams, the filamentous fungus Penicillium rubens (previously named Penicillium chrysogenum) has been subjected to an extensive classical strain improvement (CSI) program during the last few decades. This has led to the accumulation of many mutations that were spread over the genome. Detailed analysis reveals that several mutations targeted genes that encode enzymes involved in amino acid metabolism, in particular biosynthesis of l-cysteine, one of the amino acids used for β-lactam production. To examine the impact of the mutations on enzyme function, the respective genes with and without the mutations were cloned and expressed in Escherichia coli, purified, and enzymatically analyzed. Mutations severely impaired the activities of a threonine and serine deaminase, and this inactivates metabolic pathways that compete for l-cysteine biosynthesis. Tryptophan synthase, which converts l-serine into l-tryptophan, was inactivated by a mutation, whereas a mutation in 5-aminolevulinate synthase, which utilizes glycine, was without an effect. Importantly, CSI caused increased expression levels of a set of genes directly involved in cysteine biosynthesis. These results suggest that CSI has resulted in improved cysteine biosynthesis by the inactivation of the enzymatic conversions that directly compete for resources with the cysteine biosynthetic pathway, consistent with the notion that cysteine is a key component during penicillin production.IMPORTANCE Penicillium rubens is an important industrial producer of β-lactam antibiotics. High levels of penicillin production were enforced through extensive mutagenesis during a classical strain improvement (CSI) program over 70 years. Several mutations targeted amino acid metabolism and resulted in enhanced l-cysteine biosynthesis. This work provides a molecular explanation for the interrelation between secondary metabolite production and amino acid metabolism and how classical strain improvement has resulted in improved production strains.
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Harun-Ur-Rashid M, Oogai S, Parveen S, Inafuku M, Iwasaki H, Fukuta M, Amzad Hossain M, Oku H. Molecular cloning of putative chloroplastic cysteine synthase in Leucaena leucocephala. JOURNAL OF PLANT RESEARCH 2020; 133:95-108. [PMID: 31828681 DOI: 10.1007/s10265-019-01158-y] [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: 07/16/2019] [Accepted: 12/02/2019] [Indexed: 05/14/2023]
Abstract
Cysteine biosynthesis is directed by the successive commitments of serine acetyltransferase, and O-acetylserine (thiol) lyase (OASTL) compounds, which subsequently frame the decameric cysteine synthase complex. The isoforms of OASTL are found in three compartments of the cell: the cytosol, plastid, and mitochondria. In this investigation, we first isolated putative chloroplastic OASTL (Ch-OASTL) from Leucaena leucocephala, and the Ch-OASTL was then expressed in BL21-competent Escherichia coli. The putative Ch-OASTL cDNA clone had 1,543 base pairs with 391 amino acids in its open reading frame and a molecular weight of 41.54 kDa. The purified protein product exhibited cysteine synthesis ability, but not mimosine synthesis activity. However, they both make the common α-aminoacrylate intermediate in their first half reaction scheme with the conventional substrate O-acetyl serine (OAS). Hence, we considered putative Ch-OASTL a cysteine-specific enzyme. Kinetic studies demonstrated that the optimum pH for cysteine synthesis was 7.0, and the optimum temperature was 40 °C. In the cysteine synthesis assay, the Km and kcat values were 838 ± 26 µM and 72.83 s-1 for OAS, respectively, and 60 ± 2 µM and 2.43 s-1 for Na2S, respectively. We can infer that putative Ch-OASTL regulatory role is considered a sensor for sulfur constraint conditions, and it acts as a forerunner of various metabolic compound molecules.
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Affiliation(s)
- Md Harun-Ur-Rashid
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
- Department of Genetics and Plant Breeding, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, 1207, Bangladesh
| | - Shigeki Oogai
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
| | - Shahanaz Parveen
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
- Molecular Biotechnology Group, Tropical Biosphere Research Center, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan
- Department of Genetics and Plant Breeding, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, 1207, Bangladesh
| | - Masashi Inafuku
- Molecular Biotechnology Group, Tropical Biosphere Research Center, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan
| | - Hironori Iwasaki
- Molecular Biotechnology Group, Tropical Biosphere Research Center, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan
| | - Masakazu Fukuta
- Department of Subtropical Biochemistry and Biotechnology, Graduate School of Agriculture, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan.
| | - Md Amzad Hossain
- Department of Subtropical Biochemistry and Biotechnology, Graduate School of Agriculture, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan
| | - Hirosuke Oku
- Molecular Biotechnology Group, Tropical Biosphere Research Center, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa, 903-0213, Japan
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Huang H, Zheng X, Yang S, Chen Y. More than sulfidation: Roles of biogenic sulfide in attenuating the impacts of CuO nanoparticle on antibiotic resistance genes during sludge anaerobic digestion. WATER RESEARCH 2019; 158:1-10. [PMID: 31004981 DOI: 10.1016/j.watres.2019.04.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 04/07/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023]
Abstract
Biogenic sulfide (BS) in anaerobic digesters was previously suggested to mitigate the potential impacts of metallic nanoparticles (M-NPs) on antibiotic resistance genes (ARGs) propagation by sulfidation of the M-NPs. In this study, a new role of BS in regulating ARGs responses to M-NPs is reported. It was observed that CuO NPs at environmentally relevant level had no significant effects on the spread of ARGs. However, higher dosage (50 mg/gTSS) contributed to the propagation of ARGs, whose abundances would be effectively reduced by 74-115% if BS production was stimulated. Instead, introduction of EDTA, a metal ion chelator, resulted in much lower attenuation efficiencies (12-40%), indicating that restriction of the bioavailability of CuO NPs might not be the only reason for the buffering of ARG responses in the presence of BS. Further investigation showed that the presence of BS together with activation of key enzymes (O-acetyl serine sulfhydrylase and γ-glutamylcysteine synthetase) supplied and favored the biosynthesis and transformation of cysteine, which mitigated the oxidative stress induced by CuO NPs. Moreover, the amounts of cysteine and its metabolite glutathione in sludge were associated with the abundances of ARGs negatively, implying that in situ generated cysteine was the important ARGs regulator. Exploration of possible mechanisms revealed that the biosynthesized cysteine might limit gene transfer potential via mobile genetic elements, as cysteine restricted the abundances of intI 1, Tn916/1545 and ISCR 1. In addition, the cysteine remarkably alleviated the copper stress and copper resistance, which in turn blocked possible co-selection between copper and antibiotic resistance. This work provides new insight into attenuation of the bio-effects of NPs in digesters.
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Affiliation(s)
- Haining Huang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Xiong Zheng
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
| | - Shouye Yang
- State Key Laboratory of Marine Geology, School of Ocean and Earth Science, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Yinguang Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
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Cai YT, Zhang H, Qi YP, Ye X, Huang ZR, Guo JX, Chen LS, Yang LT. Responses of reactive oxygen species and methylglyoxal metabolisms to magnesium-deficiency differ greatly among the roots, upper and lower leaves of Citrus sinensis. BMC PLANT BIOLOGY 2019; 19:76. [PMID: 30770733 PMCID: PMC6377732 DOI: 10.1186/s12870-019-1683-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 02/11/2019] [Indexed: 05/09/2023]
Abstract
BACKGROUND Magnesium (Mg)-deficiency is one of the most prevalent physiological disorders causing a reduction in Citrus yield and quality. 'Xuegan' (Citrus sinensis) seedlings were irrigated for 16 weeks with nutrient solution containing 2 mM (Mg-sufficiency) or 0 mM (Mg-deficiency) Mg(NO3)2. Thereafter, we investigated the Mg-deficient effects on gas exchange and chlorophyll a fluorescence in the upper and lower leaves, and Mg, reactive oxygen species (ROS) and methylglyoxal (MG) metabolisms in the roots, lower and upper leaves. The specific objectives were to corroborate the hypothesis that the responses of ROS and MG metabolisms to Mg-deficiency were greater in the lower leaves than those in the upper leaves, and different between the leaves and roots. RESULTS Mg level was higher in the Mg-deficient upper leaves than that in the Mg-deficient lower leaves. This might be responsible for the Mg-deficiency-induced larger alterations of all the measured parameters in the lower leaves than those in the upper leaves, but they showed similar change patterns between the Mg-deficient lower and upper leaves. Accordingly, Mg-deficiency increased greatly their differences between the lower and upper leaves. Most of parameters involved in ROS and MG metabolisms had similar variation trends and degrees between the Mg-deficient lower leaves and roots, but several parameters (namely glutathione S-transferase, sulfite reductase, ascorbate and dehydroascorbate) displayed the opposite variation trends. Obviously, differences existed in the Mg-deficiency-induced alterations of ROS and MG metabolisms between the lower leaves and roots. Although the activities of most antioxidant and sulfur metabolism-related enzymes and glyoxalase I and the level of reduced glutathione in the Mg-deficient leaves and roots and the level of ascorbate in the leaves were kept in higher levels, the levels of malonaldehyde and MG and/or electrolyte leakage were increased in the Mg-deficient lower and upper leaves and roots, especially in the Mg-deficient lower leaves and roots. CONCLUSIONS The ROS and MG detoxification systems as a whole did not provide sufficient detoxification capacity to prevent the Mg-deficiency-induced production and accumulation of ROS and MG, thus leading to lipid peroxidation and the loss of plasma membrane integrity, especially in the lower leaves and roots.
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Affiliation(s)
- Yan-Tong Cai
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Han Zhang
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Yi-Ping Qi
- Institute of Materia Medica, Fujian Academy of Medical Sciences, Fuzhou, 350001 China
| | - Xin Ye
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Zeng-Rong Huang
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Jiu-Xin Guo
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Li-Song Chen
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Lab of Soil Ecosystem Health and Regulation, Fujian Province University, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- The Higher Educational Key Laboratory of Fujian Province for Soil Ecosystem Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Lin-Tong Yang
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
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Guo P, Qi YP, Cai YT, Yang TY, Yang LT, Huang ZR, Chen LS. Aluminum effects on photosynthesis, reactive oxygen species and methylglyoxal detoxification in two Citrus species differing in aluminum tolerance. TREE PHYSIOLOGY 2018; 38:1548-1565. [PMID: 29718474 DOI: 10.1093/treephys/tpy035] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 03/16/2018] [Indexed: 05/03/2023]
Abstract
Citrus are mainly grown in low pH soils with high active aluminum (Al). 'Xuegan' (Citrus sinensis (L.) Osbeck) and 'Shatian pummelo' (Citrus grandis (L.) Osbeck) seedlings were fertilized for 18 weeks with nutrient solution containing either 0 mM (control) or 1 mM (Al toxicity) AlCl3·6H2O. Aluminum induced decreases of biomass, leaf photosynthesis, relative water content and total soluble protein levels, and increases of methylglyoxal levels only occurred in C. grandis roots and leaves. Besides, the Al-induced decreases of pigments and alterations of chlorophyll a fluorescence transients and fluorescence parameters were greater in C. grandis leaves than those in C. sinensis leaves. Aluminum-treated C. grandis had higher stem and leaf Al levels and similar root Al levels relative to Al-treated C. sinensis, but lower Al distribution in roots and Al uptake per plant. Aluminum toxicity decreased nitrogen, phosphorus, potassium, calcium, magnesium and sulfur uptake per plant in C. grandis and C. sinensis seedlings, with the exception of Al-treated C. sinensis seedlings exhibiting increased sulfur uptake per plant and unaltered magnesium uptake per plant. Under Al-stress, macroelement uptake per plant was higher in C. sinensis than that in C. grandis. Aluminum toxicity decreased the ratios of reduced glutathione/(reduced + oxidized glutathione) and of ascorbate/(ascorbate + dehydroascorbate) only in C. grandis roots and leaves. The activities of most antioxidant enzymes, sulfur metabolism-related enzymes and glyoxalases and the levels of S-containing compounds were higher in Al-treated C. sinensis roots and leaves than those in Al-treated C. grandis ones. Thus, C. sinensis displayed higher Al tolerance than C. grandis did. The higher Al tolerance of C. sinensis might involve: (i) more Al accumulation in roots and less transport of Al from roots to shoots; (ii) efficient maintenance of nutrient homeostasis; and (iii) efficient maintenance of redox homeostasis via detoxification systems of reactive oxygen species and methylglyoxal.
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Affiliation(s)
- Peng Guo
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yi-Ping Qi
- Institute of Materia Medica, Fujian Academy of Medical Sciences, Fuzhou, China
| | - Yan-Tong Cai
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Tao-Yu Yang
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lin-Tong Yang
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zeng-Rong Huang
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Li-Song Chen
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
- The Higher Education Key Laboratory of Fujian Province for Soil Ecosystem Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
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11
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Cytosolic Cysteine Synthase Switch Cysteine and Mimosine Production in Leucaena leucocephala. Appl Biochem Biotechnol 2018; 186:613-632. [PMID: 29691793 DOI: 10.1007/s12010-018-2745-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 03/21/2018] [Indexed: 10/17/2022]
Abstract
In higher plants, multiple copies of the cysteine synthase gene are present for cysteine biosynthesis. Some of these genes also have the potential to produce various kinds of β-substitute alanine. In the present study, we cloned a 1275-bp cDNA for cytosolic O-acetylserine(thiol)lyase (cysteine synthase) (Cy-OASTL) from Leucaena leucocephala. The purified protein product showed a dual function of cysteine and mimosine synthesis. Kinetics studies showed pH optima of 7.5 and 8.0, while temperature optima of 40 and 35 °C, respectively, for cysteine and mimosine synthesis. The kinetic parameters such as apparent Km, kcat were determined for both cysteine and mimosine synthesis with substrates O-acetylserine (OAS) and Na2S or 3-hydroxy-4-pyridone (3H4P). From the in vitro results with the common substrate OAS, the apparent kcat for Cys production is over sixfold higher than mimosine synthesis and the apparent Km is 3.7 times lower, suggesting Cys synthesis is the favored pathway.
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12
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Rashid MHU, Iwasaki H, Oogai S, Fukuta M, Parveen S, Hossain MA, Anai T, Oku H. Molecular characterization of cytosolic cysteine synthase in Mimosa pudica. JOURNAL OF PLANT RESEARCH 2018; 131:319-329. [PMID: 29181648 DOI: 10.1007/s10265-017-0986-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 09/21/2017] [Indexed: 06/07/2023]
Abstract
In the cysteine and mimosine biosynthesis process, O-acetyl-L-serine (OAS) is the common substrate. In the presence of O-acetylserine (thiol) lyase (OASTL, cysteine synthase) the reaction of OAS with sulfide produces cysteine, while with 3-hydroxy-4-pyridone (3H4P) produces mimosine. The enzyme OASTL can either catalyze Cys synthesis or both Cys and mimosine. A cDNA for cytosolic OASTL was cloned from M. pudica for the first time containing 1,410 bp nucleotides. The purified protein product from overexpressed bacterial cells produced Cys only, but not mimosine, indicating it is Cys specific. Kinetic studies revealed that pH and temperature optima for Cys production were 6.5 and 50 °C, respectively. The measured Km, Kcat, and Kcat Km-1 values were 159 ± 21 µM, 33.56 s-1, and 211.07 mM-1s-1 for OAS and 252 ± 25 µM, 32.99 s-1, and 130.91 mM-1s-1 for Na2S according to the in vitro Cys assay. The Cy-OASTL of Mimosa pudica is specific to Cys production, although it contains sensory roles in sulfur assimilation and the reduction network in the intracellular environment of M. pudica.
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Affiliation(s)
- Md Harun-Ur- Rashid
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
- Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
| | - Hironori Iwasaki
- Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, Japan
| | - Shigeki Oogai
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
| | - Masakazu Fukuta
- Graduate School of Agriculture, University of the Ryukyus, Okinawa, Japan.
| | - Shahanaz Parveen
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
- Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
| | - Md Amzad Hossain
- Graduate School of Agriculture, University of the Ryukyus, Okinawa, Japan
| | - Toyoaki Anai
- Faculty of Agriculture, Saga University, Saga, Japan
| | - Hirosuke Oku
- Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, Japan
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13
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Guo P, Li Q, Qi YP, Yang LT, Ye X, Chen HH, Chen LS. Sulfur-Mediated-Alleviation of Aluminum-Toxicity in Citrus grandis Seedlings. Int J Mol Sci 2017; 18:E2570. [PMID: 29207499 PMCID: PMC5751173 DOI: 10.3390/ijms18122570] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 11/25/2017] [Accepted: 11/26/2017] [Indexed: 12/23/2022] Open
Abstract
Limited data are available on the sulfur (S)-mediated-alleviation of aluminum (Al)-toxicity in higher plants. Citrus grandis seedlings were irrigated for 18 weeks with 0.5 mM MgSO₄ or 0.5 mM MgSO₄ + 0.5 mM Na₂SO₄, and 0 (-Al) or 1 mM AlCl₃·6H₂O (+Al, Al-toxicity). Under Al-toxicity, S decreased the level of Al in leaves; increased the relative water content (RWC) of roots and leaves, the contents of phosphorus (P), calcium (Ca) and magnesium (Mg) per plant, the dry weights (DW) of roots and shoots, the ratios of root DW/shoot DW, and the Al-induced secretion of citrate from root; and alleviated the Al-induced inhibition of photosynthesis via mitigating the Al-induced decrease of electron transport capacity resulting from the impaired photosynthetic electron transport chain. In addition to decreasing the Al-stimulated H₂O₂ production, the S-induced upregulation of both S metabolism-related enzymes and antioxidant enzymes also contributed to the S-mediated-alleviation of oxidative damage in Al-treated roots and leaves. Decreased transport of Al from roots to shoots and relatively little accumulation of Al in leaves, and increased leaf and root RWC and P, Ca, and Mg contents per plant might also play a role in the S-mediated-alleviation of Al-toxicity.
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Affiliation(s)
- Peng Guo
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University (FAFU), Fuzhou 350002, China.
| | - Qiang Li
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University (FAFU), Fuzhou 350002, China.
| | - Yi-Ping Qi
- Institute of Materia Medica, Fujian Academy of Medical Sciences, Fuzhou 350002, China.
| | - Lin-Tong Yang
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University (FAFU), Fuzhou 350002, China.
| | - Xin Ye
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University (FAFU), Fuzhou 350002, China.
| | - Huan-Huan Chen
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University (FAFU), Fuzhou 350002, China.
| | - Li-Song Chen
- Institute of Plant Nutritional Physiology and Molecular Biology, College of Resources and Environment, Fujian Agriculture and Forestry University (FAFU), Fuzhou 350002, China.
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, FAFU, Fuzhou 350002, China.
- The Higher Education Key Laboratory of Fujian Province for Soil Ecosystem Health and Regulation, College of Resources and Environment, FAFU, Fuzhou 350002, China.
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Tahir J, Dijkwel P. β-Substituting alanine synthases: roles in cysteine metabolism and abiotic and biotic stress signalling in plants. FUNCTIONAL PLANT BIOLOGY : FPB 2016; 43:307-323. [PMID: 32480463 DOI: 10.1071/fp15272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/10/2015] [Indexed: 06/11/2023]
Abstract
Cysteine is required for the synthesis of proteins and metabolites, and is therefore an indispensable compound for growth and development. The β-substituting alanine synthase (BSAS) gene family encodes enzymes known as O-acetylserine thiol lyases (OASTLs), which carry out cysteine biosynthesis in plants. The functions of the BSAS isoforms have been reported to be crucial in assimilation of S and cysteine biosynthesis, and homeostasis in plants. In this review we explore the functional variation in this classic pyridoxal-phosphate-dependent enzyme family of BSAS isoforms. We discuss how specialisation and divergence in BSAS catalytic activities makes a more dynamic set of biological routers that integrate cysteine metabolism and abiotic and biotic stress signalling in Arabidopsis thaliana (L.) Heynh. and also other species. Our review presents a universal scenario in which enzymes modulating cysteine metabolism promote survival and fitness of the species by counteracting internal and external stress factors.
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Affiliation(s)
- Jibran Tahir
- Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - Paul Dijkwel
- Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
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15
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El-Sayed ASA, Yassin MA, Ali GS. Transcriptional and Proteomic Profiling of Aspergillus flavipes in Response to Sulfur Starvation. PLoS One 2015; 10:e0144304. [PMID: 26633307 PMCID: PMC4669086 DOI: 10.1371/journal.pone.0144304] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 11/15/2015] [Indexed: 12/19/2022] Open
Abstract
Aspergillus flavipes has received considerable interest due to its potential to produce therapeutic enzymes involved in sulfur amino acid metabolism. In natural habitats, A. flavipes survives under sulfur limitations by mobilizing endogenous and exogenous sulfur to operate diverse cellular processes. Sulfur limitation affects virulence and pathogenicity, and modulates proteome of sulfur assimilating enzymes of several fungi. However, there are no previous reports aimed at exploring effects of sulfur limitation on the regulation of A. flavipes sulfur metabolism enzymes at the transcriptional, post-transcriptional and proteomic levels. In this report, we show that sulfur limitation affects morphological and physiological responses of A. flavipes. Transcription and enzymatic activities of several key sulfur metabolism genes, ATP-sulfurylase, sulfite reductase, methionine permease, cysteine synthase, cystathionine β- and γ-lyase, glutathione reductase and glutathione peroxidase were increased under sulfur starvation conditions. A 50 kDa protein band was strongly induced by sulfur starvation, and the proteomic analyses of this protein band using LC-MS/MS revealed similarity to many proteins involved in the sulfur metabolism pathway.
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Affiliation(s)
- Ashraf S. A. El-Sayed
- Botany and Microbiology Department, Faculty of Science, Zagazig University, 44519, Zagazig, Egypt
- Mid-Florida Research and Education Center, Department of Plant Pathology, University of Florida, Apopka, Florida 32703, United States of America
- * E-mail: (GSA); (AES)
| | - Marwa A. Yassin
- Botany and Microbiology Department, Faculty of Science, Zagazig University, 44519, Zagazig, Egypt
| | - Gul Shad Ali
- Mid-Florida Research and Education Center, Department of Plant Pathology, University of Florida, Apopka, Florida 32703, United States of America
- * E-mail: (GSA); (AES)
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16
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Abstract
In contrast to animals, which release the signal molecule sulfide in small amounts from cysteine and its derivates, phototrophic eukaryotes generate sulfide as an essential intermediate of the sulfur assimilation pathway. Additionally, iron-sulfur cluster turnover and cyanide detoxification might contribute to the release of sulfide in mitochondria. However, sulfide is a potent inhibitor of cytochrome c oxidase in mitochondria. Thus, efficient sulfide detoxification mechanisms are required in mitochondria to ensure adequate energy production and consequently survival of the plant cell. Two enzymes have been recently described to catalyze sulfide detoxification in mitochondria of Arabidopsis thaliana, O-acetylserine(thiol)lyase C (OAS-TL C), and the sulfur dioxygenase (SDO) ethylmalonic encephalopathy protein 1 (ETHE1). Biochemical characterization of sulfide producing and consuming enzymes in mitochondria of plants is fundamental to understand the regulatory network that enables mitochondrial sulfide homeostasis under nonstressed and stressed conditions. In this chapter, we provide established protocols to determine the activity of the sulfide releasing enzyme β-cyanoalanine synthase as well as sulfide-consuming enzymes OAS-TL and SDO. Additionally, we describe a reliable and efficient method to purify OAS-TL proteins from plant material.
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Affiliation(s)
- Hannah Birke
- Centre for Organismal Studies Heidelberg, University of Heidelberg, Heidelberg, Germany
| | | | - Markus Wirtz
- Centre for Organismal Studies Heidelberg, University of Heidelberg, Heidelberg, Germany
| | - Rüdiger Hell
- Centre for Organismal Studies Heidelberg, University of Heidelberg, Heidelberg, Germany.
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17
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Tavares S, Wirtz M, Beier MP, Bogs J, Hell R, Amâncio S. Characterization of the serine acetyltransferase gene family of Vitis vinifera uncovers differences in regulation of OAS synthesis in woody plants. FRONTIERS IN PLANT SCIENCE 2015; 6:74. [PMID: 25741355 PMCID: PMC4330696 DOI: 10.3389/fpls.2015.00074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 01/28/2015] [Indexed: 05/08/2023]
Abstract
In higher plants cysteine biosynthesis is catalyzed by O-acetylserine(thiol)lyase (OASTL) and represents the last step of the assimilatory sulfate reduction pathway. It is mainly regulated by provision of O-acetylserine (OAS), the nitrogen/carbon containing backbone for fixation of reduced sulfur. OAS is synthesized by Serine acetyltransferase (SERAT), which reversibly interacts with OASTL in the cysteine synthase complex (CSC). In this study we identify and characterize the SERAT gene family of the crop plant Vitis vinifera. The identified four members of the VvSERAT protein family are assigned to three distinct groups upon their sequence similarities to Arabidopsis SERATs. Expression of fluorescently labeled VvSERAT proteins uncover that the sub-cellular localization of VvSERAT1;1 and VvSERAT3;1 is the cytosol and that VvSERAT2;1 and VvSERAT2;2 localize in addition in plastids and mitochondria, respectively. The purified VvSERATs of group 1 and 2 have higher enzymatic activity than VvSERAT3;1, which display a characteristic C-terminal extension also present in AtSERAT3;1. VvSERAT1;1 and VvSERAT2;2 are evidenced to form the CSC. CSC formation activates VvSERAT2;2, by releasing CSC-associated VvSERAT2;2 from cysteine inhibition. Thus, subcellular distribution of SERAT isoforms and CSC formation in cytosol and mitochondria is conserved between Arabidopsis and grapevine. Surprisingly, VvSERAT2;1 lack the canonical C-terminal tail of plant SERATs, does not form the CSC and is almost insensitive to cysteine inhibition (IC50 = 1.9 mM cysteine). Upon sulfate depletion VvSERAT2;1 is strongly induced at the transcriptional level, while transcription of other VvSERATs is almost unaffected in sulfate deprived grapevine cell suspension cultures. Application of abiotic stresses to soil grown grapevine plants revealed isoform-specific induction of VvSERAT2;1 in leaves upon drought, whereas high light- or temperature- stress hardly trigger VvSERAT2;1 transcription.
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Affiliation(s)
- Sílvia Tavares
- Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de LisboaLisbon, Portugal
- Plant Cell Biology Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de LisboaOeiras, Portugal
| | - Markus Wirtz
- Centre for Organismal Studies Heidelberg, University of HeidelbergHeidelberg, Germany
| | - Marcel P. Beier
- Centre for Organismal Studies Heidelberg, University of HeidelbergHeidelberg, Germany
| | - Jochen Bogs
- Centre for Organismal Studies Heidelberg, University of HeidelbergHeidelberg, Germany
- Studiengang Weinbau und Oenologie, Dienstleistungszentrum Laendlicher Raum RheinpfalzNeustadt, Germany
- Fachbereich 1, Life Sciences and Engineering, Fachhochschule BingenBingen am Rhein, Germany
| | - Rüdiger Hell
- Centre for Organismal Studies Heidelberg, University of HeidelbergHeidelberg, Germany
| | - Sara Amâncio
- Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de LisboaLisbon, Portugal
- *Correspondence: Sara Amâncio, Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal e-mail:
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18
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Hydrogen sulfide in plants: From dissipation of excess sulfur to signaling molecule. Nitric Oxide 2014; 41:72-8. [DOI: 10.1016/j.niox.2014.02.005] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 02/11/2014] [Accepted: 02/17/2014] [Indexed: 11/21/2022]
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19
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O'Leary B, Preston GM, Sweetlove LJ. Increased β-cyanoalanine nitrilase activity improves cyanide tolerance and assimilation in Arabidopsis. MOLECULAR PLANT 2014; 7:231-243. [PMID: 23825089 DOI: 10.1093/mp/sst110] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Plants naturally produce cyanide (CN) which is maintained at low levels in their cells by a process of rapid assimilation. However, high concentrations of environmental CN associated with activities such as industrial pollution are toxic to plants. There is thus an interest in increasing the CN detoxification capacity of plants as a potential route to phytoremediation. Here, Arabidopsis seedlings overexpressing the Pseudomonas fluorescens β-cyanoalanine nitrilase pinA were compared with wild-type and a β-cyanoalanine nitrilase knockout line (ΔAtnit4) for growth in the presence of exogenous CN. After incubation with CN, +PfpinA seedlings had increased root length, increased fresh weight, and decreased leaf bleaching compared with wild-type, indicating increased CN tolerance. The increased tolerance was achieved without an increase in β-cyanoalanine synthase activity, the other enzyme in the cyanide assimilation pathway, suggesting that nitrilase activity is the limiting factor for cyanide detoxification. Labeling experiments with [¹³C]KCN demonstrated that the altered CN tolerance could be explained by differences in flux from CN to Asn caused by altered β-cyanoalanine nitrilase activity. Metabolite profiling after CN treatment provided new insight into downstream metabolism, revealing onward metabolism of Asn by the photorespiratory nitrogen cycle and accumulation of aromatic amino acids.
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Affiliation(s)
- Brendan O'Leary
- Department of Plant Sciences, University of Oxford, Oxford, UK
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20
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Yi H, Jez JM. Assessing functional diversity in the soybean β-substituted alanine synthase enzyme family. PHYTOCHEMISTRY 2012; 83:15-24. [PMID: 22986002 DOI: 10.1016/j.phytochem.2012.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 06/12/2012] [Accepted: 08/10/2012] [Indexed: 05/08/2023]
Abstract
In plants, proteins of the β-substituted alanine synthase (BSAS) enzyme family perform a diverse range of reactions, including formation of cysteine from O-acetylserine and sulfide, detoxification of cyanide by its addition to cysteine, the breakdown of cysteine into pyruvate, ammonia, and sulfide, and the synthesis of S-sulfocysteine. With the completed genome sequence of soybean (Glycine max (L.) Merr. cv. Williams 82), the functional diversity of the BSAS in this highly duplicated plant species was examined to determine whether soybean BSAS enzymes catalyze the various reactions connected to cysteine metabolism. The 16 soybean BSAS can be grouped into clades that are similar to those observed in Arabidopsis. Biochemical analysis of soybean BSAS proteins demonstrate that enzymes of clades I and III function as O-acetylserine sulfhydrylases for cysteine synthesis, clade II encodes cysteine desulfhydrase activity, and that clade V proteins function as β-cyanoalanine synthase for cyanide detoxification. Although clade IV is similar to Arabidopsis S-sulfocysteine synthase, this activity was not detected in the soybean homolog. Overall, our results show that bioinformatics approach provides a useful method to assess the biochemical properties of BSAS enzymes in plant species.
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Affiliation(s)
- Hankuil Yi
- Department of Biology, Washington University in St. Louis, One Brookings Drive, Campus Box 1137, St. Louis, MO 63130, USA
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21
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Cysteine biosynthesis, in concert with a novel mechanism, contributes to sulfide detoxification in mitochondria of Arabidopsis thaliana. Biochem J 2012; 445:275-83. [DOI: 10.1042/bj20120038] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In higher plants, biosynthesis of cysteine is catalysed by OAS-TL [O-acetylserine(thiol)lyase], which replaces the activated acetyl group of O-acetylserine with sulfide. The enzyme is present in cytosol, plastids and mitochondria of plant cells. The sole knockout of mitochondrial OAS-TL activity (oastlC) leads to significant reduction of growth in Arabidopsis thaliana. The reason for this phenotype is still enigmatic, since mitochondrial OAS-TL accounts only for approximately 5% of total OAS-TL activity. In the present study we demonstrate that sulfide specifically intoxicates Complex IV activity, but not electron transport through Complexes II and III in isolated mitochondria of oastlC plants. Loss of mitochondrial OAS-TL activity resulted in significant inhibition of dark respiration under certain developmental conditions. The abundance of mitochondrially encoded proteins and Fe–S cluster-containing proteins was not affected in oastlC. Furthermore, oastlC seedlings were insensitive to cyanide, which is detoxified by β-cyano-alanine synthase in mitochondria at the expense of cysteine. These results indicate that in situ biosynthesis of cysteine in mitochondria is not mandatory for translation, Fe–S cluster assembly and cyanide detoxification. Finally, we uncover an OAS-TL-independent detoxification system for sulfide in mitochondria of Arabidopsis that allows oastlC plants to cope with high sulfide levels caused by abiotic stresses.
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22
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Birke H, Müller SJ, Rother M, Zimmer AD, Hoernstein SNW, Wesenberg D, Wirtz M, Krauss GJ, Reski R, Hell R. The relevance of compartmentation for cysteine synthesis in phototrophic organisms. PROTOPLASMA 2012; 249 Suppl 2:S147-55. [PMID: 22543690 DOI: 10.1007/s00709-012-0411-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 04/10/2012] [Indexed: 05/18/2023]
Abstract
In the vascular plant Arabidopsis thaliana, synthesis of cysteine and its precursors O-acetylserine and sulfide is distributed between the cytosol, chloroplasts, and mitochondria. This compartmentation contributes to regulation of cysteine synthesis. In contrast to Arabidopsis, cysteine synthesis is exclusively restricted to chloroplasts in the unicellular green alga Chlamydomonas reinhardtii. Thus, the question arises, whether specification of compartmentation was driven by multicellularity and specified organs and tissues. The moss Physcomitrella patens colonizes land but is still characterized by a simple morphology compared to vascular plants. It was therefore used as model organism to study evolution of compartmented cysteine synthesis. The presence of O-acetylserine(thiol)lyase (OAS-TL) proteins, which catalyze the final step of cysteine synthesis, in different compartments was applied as criterion. Purification and characterization of native OAS-TL proteins demonstrated the presence of five OAS-TL protein species encoded by two genes in Physcomitrella. At least one of the gene products is dual targeted to plastids and cytosol, as shown by combination of GFP fusion localization studies, purification of chloroplasts, and identification of N termini from native proteins. The bulk of OAS-TL protein is targeted to plastids, whereas there is no evidence for a mitochondrial OAS-TL isoform and only a minor part of OAS-TL protein is localized in the cytosol. This demonstrates that subcellular diversification of cysteine synthesis is already initialized in Physcomitrella but appears to gain relevance later during evolution of vascular plants.
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Affiliation(s)
- Hannah Birke
- Centre for Organismal Studies Heidelberg, Department Plant Molecular Biology, University of Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany
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23
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Hell R, Wirtz M. Molecular Biology, Biochemistry and Cellular Physiology of Cysteine Metabolism in Arabidopsis thaliana. THE ARABIDOPSIS BOOK 2011; 9:e0154. [PMID: 22303278 PMCID: PMC3268551 DOI: 10.1199/tab.0154] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cysteine is one of the most versatile molecules in biology, taking over such different functions as catalysis, structure, regulation and electron transport during evolution. Research on Arabidopsis has contributed decisively to the understanding of cysteine synthesis and its role in the assimilatory pathways of S, N and C in plants. The multimeric cysteine synthase complex is present in the cytosol, plastids and mitochondria and forms the centre of a unique metabolic sensing and signaling system. Its association is reversible, rendering the first enzyme of cysteine synthesis active and the second one inactive, and vice-versa. Complex formation is triggered by the reaction intermediates of cysteine synthesis in response to supply and demand and gives rise to regulation of genes of sulfur metabolism to adjust cellular sulfur homeostasis. Combinations of biochemistry, forward and reverse genetics, structural- and cell-biology approaches using Arabidopsis have revealed new enzyme functions and the unique pattern of spatial distribution of cysteine metabolism in plant cells. These findings place the synthesis of cysteine in the centre of the network of primary metabolism.
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Affiliation(s)
- Rüdiger Hell
- Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany
| | - Markus Wirtz
- Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany
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24
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Kopriva S, Mugford SG, Matthewman C, Koprivova A. Plant sulfate assimilation genes: redundancy versus specialization. PLANT CELL REPORTS 2009; 28:1769-80. [PMID: 19876632 DOI: 10.1007/s00299-009-0793-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 10/13/2009] [Accepted: 10/14/2009] [Indexed: 05/03/2023]
Abstract
Sulfur is an essential nutrient present in the amino acids cysteine and methionine, co-enzymes and vitamins. Plants and many microorganisms are able to utilize inorganic sulfate and assimilate it into these compounds. Sulfate assimilation in plants has been extensively studied because of the many functions of sulfur in plant metabolism and stress defense. The pathway is highly regulated in a demand-driven manner. A characteristic feature of this pathway is that most of its components are encoded by small multigene families. This may not be surprising, as several steps of sulfate assimilation occur in multiple cellular compartments, but the composition of the gene families is more complex than simply organellar versus cytosolic forms. Recently, several of these gene families have been investigated in a systematic manner utilizing Arabidopsis reverse genetics tools. In this review, we will assess how far the individual isoforms of sulfate assimilation enzymes possess specific functions and what level of genetic redundancy is retained. We will also compare the genomic organization of sulfate assimilation in the model plant Arabidopsis thaliana with other plant species to find common and species-specific features of the pathway.
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25
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A redox basis for metronidazole resistance in Helicobacter pylori. Antimicrob Agents Chemother 2009; 53:1884-91. [PMID: 19223619 DOI: 10.1128/aac.01449-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Metronidazole resistance in Helicobacter pylori has been attributed to mutations in rdxA or frxA. Insufficient data correlating RdxA and/or FrxA with the resistant phenotype, and the emergence of resistant strains with no mutations in either rdxA or frxA, indicated that the molecular basis of H. pylori resistance to metronidazole required further characterization. The rdxA and frxA genes of four matched pairs of metronidazole-susceptible and -resistant strains were sequenced. The resistant strains had mutations in either rdxA, frxA, neither gene, or both genes. The reduction rates of five substrates suggested that metabolic differences between susceptible and resistant strains cannot be explained only by mutations in rdxA and/or frxA. A more global approach to understanding the resistance phenotype was taken by employing two-dimensional gel electrophoresis combined with tandem mass spectrometry analyses to identify proteins differentially expressed by the matched pair of strains with no mutations in rdxA or frxA. Proteins involved in the oxireduction of ferredoxin were downregulated in the resistant strain. Other redox enzymes, such as thioredoxin reductase, alkyl hydroperoxide reductase, and superoxide dismutase, showed a pI change in the resistant strain. The data suggested that metronidazole resistance involved more complex metabolic changes than specific gene mutations, and they provided evidence of a role for the intracellular redox potential in the development of resistance.
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Lai KW, Yau CP, Tse YC, Jiang L, Yip WK. Heterologous expression analyses of rice OsCAS in Arabidopsis and in yeast provide evidence for its roles in cyanide detoxification rather than in cysteine synthesis in vivo. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:993-1008. [PMID: 19181864 PMCID: PMC2652057 DOI: 10.1093/jxb/ern343] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
While most dicot plants produce little ethylene in their vegetative stage, many monocots such as rice liberate a relatively large amount of ethylene with cyanide as a co-product in their seedling stage when etiolated. One of the known functions of beta-cyanoalanine synthase (CAS) is to detoxify the co-product cyanide during ethylene biosynthesis in higher plants. Based on a tryptic peptide sequence obtained from a partially purified CAS activity protein preparation in etiolated rice seedlings, the full-length putative rice CAS-encoding cDNA sequence (OsCAS), which is homologous to those O-acetylserine sulphydrylase (OASS) genes, was cloned. Unlike most of the CAS genes reported from dicots, the transcription of OsCAS is promoted by auxins but suppressed by ethylene. To address the function and the subcellular localization of this gene product in planta, a binary vector construct consisting of this gene appended with a yellow fluorescent protein-encoding sequence was employed to transform Arabidopsis. Specific activities on CAS and OASS of the purified recombinant protein from transgenic Arabidopsis were 181.04 micromol H(2)S mg(-1) protein min(-1) and 0.92 micromol Cys mg(-1) protein min(-1), respectively, indicating that OsCAS favours CAS activity. The subcellular localization of OsCAS was found mostly in the mitochondria by immunogold electron-microscopy. Chemical cross-linking and in-gel assay on a heterodimer composed of functional and non-functional mutants in a yeast expression system on OsCAS suggested that OsCAS functions as a homodimer, similar to that of OASS. Despite the structural similarity of OsCAS with OASS, it has also been confirmed that OsCAS could not interact with serine-acetyltransferase, indicating that OsCAS mainly functions in cyanide detoxification.
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Affiliation(s)
- Kwok Wai Lai
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Chi Ping Yau
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Yu Chung Tse
- Department of Biology and Molecular Biotechnology Program, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Department of Biology and Molecular Biotechnology Program, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, China
| | - Wing Kin Yip
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, China
- To whom correspondence should be addressed. E-mail:
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Haas FH, Heeg C, Queiroz R, Bauer A, Wirtz M, Hell R. Mitochondrial serine acetyltransferase functions as a pacemaker of cysteine synthesis in plant cells. PLANT PHYSIOLOGY 2008; 148:1055-67. [PMID: 18753283 PMCID: PMC2556817 DOI: 10.1104/pp.108.125237] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 08/25/2008] [Indexed: 05/20/2023]
Abstract
Cysteine (Cys) synthesis in plants is carried out by two sequential reactions catalyzed by the rate-limiting enzyme serine acetyltransferase (SAT) and excess amounts of O-acetylserine(thiol)lyase. Why these reactions occur in plastids, mitochondria, and cytosol of plants remained unclear. Expression of artificial microRNA (amiRNA) against Sat3 encoding mitochondrial SAT3 in transgenic Arabidopsis (Arabidopsis thaliana) plants demonstrates that mitochondria are the most important compartment for the synthesis of O-acetylserine (OAS), the precursor of Cys. Reduction of RNA levels, protein contents, SAT enzymatic activity, and phenotype strongly correlate in independent amiSAT3 lines and cause significantly retarded growth. The expression of the other four Sat genes in the Arabidopsis genome are not affected by amiRNA-SAT3 according to quantitative real-time polymerase chain reaction and microarray analyses. Application of radiolabeled serine to leaf pieces revealed severely reduced incorporation rates into Cys and even more so into glutathione. Accordingly, steady-state levels of OAS are 4-fold reduced. Decrease of sulfate reduction-related genes is accompanied by an accumulation of sulfate in amiSAT3 lines. These results unequivocally show that mitochondria provide the bulk of OAS in the plant cell and are the likely site of flux regulation. Together with recent data, the cytosol appears to be a major site of Cys synthesis, while plastids contribute reduced sulfur as sulfide. Thus, Cys synthesis in plants is significantly different from that in nonphotosynthetic eukaryotes at the cellular level.
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Affiliation(s)
- Florian H Haas
- Heidelberg Institute for Plant Sciences, Heidelberg University, Heidelberg, Germany
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Watanabe M, Mochida K, Kato T, Tabata S, Yoshimoto N, Noji M, Saito K. Comparative genomics and reverse genetics analysis reveal indispensable functions of the serine acetyltransferase gene family in Arabidopsis. THE PLANT CELL 2008; 20:2484-96. [PMID: 18776059 PMCID: PMC2570737 DOI: 10.1105/tpc.108.060335] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 08/07/2008] [Accepted: 08/18/2008] [Indexed: 05/19/2023]
Abstract
Ser acetyltransferase (SERAT), which catalyzes O-acetyl-Ser (OAS) formation, plays a key role in sulfur assimilation and Cys synthesis. Despite several studies on SERATs from various plant species, the in vivo function of multiple SERAT genes in plant cells remains unaddressed. Comparative genomics studies with the five genes of the SERAT gene family in Arabidopsis thaliana indicated that all three Arabidopsis SERAT subfamilies are conserved across five plant species with available genome sequences. Single and multiple knockout mutants of all Arabidopsis SERAT gene family members were analyzed. All five quadruple mutants with a single gene survived, with three mutants showing dwarfism. However, the quintuple mutant lacking all SERAT genes was embryo-lethal. Thus, all five isoforms show functional redundancy in vivo. The developmental and compartment-specific roles of each SERAT isoform were also demonstrated. Mitochondrial SERAT2;2 plays a predominant role in cellular OAS formation, while plastidic SERAT2;1 contributes less to OAS formation and subsequent Cys synthesis. Three cytosolic isoforms, SERAT1;1, SERAT3;1, and SERAT3;2, may play a major role during seed development. Thus, the evolutionally conserved SERAT gene family is essential in cellular processes, and the substrates and products of SERAT must be exchangeable between the cytosol and organelles.
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Affiliation(s)
- Mutsumi Watanabe
- Graduate School of Pharmaceutical Sciences, Chiba University, Inage-ku, Chiba 263-8522, Japan
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Hell R, Wirtz M. Metabolism of Cysteine in Plants and Phototrophic Bacteria. SULFUR METABOLISM IN PHOTOTROPHIC ORGANISMS 2008. [DOI: 10.1007/978-1-4020-6863-8_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Phylogenetic Analysis of Sulfate Assimilation and Cysteine Biosynthesis in Phototrophic Organisms. SULFUR METABOLISM IN PHOTOTROPHIC ORGANISMS 2008. [DOI: 10.1007/978-1-4020-6863-8_3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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31
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Heeg C, Kruse C, Jost R, Gutensohn M, Ruppert T, Wirtz M, Hell R. Analysis of the Arabidopsis O-acetylserine(thiol)lyase gene family demonstrates compartment-specific differences in the regulation of cysteine synthesis. THE PLANT CELL 2008; 20:168-85. [PMID: 18223034 PMCID: PMC2254930 DOI: 10.1105/tpc.107.056747] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 12/21/2007] [Accepted: 01/10/2008] [Indexed: 05/18/2023]
Abstract
Cys synthesis in plants takes place in plastids, cytosol, and mitochondria. Why Cys synthesis is required in all compartments with autonomous protein biosynthesis and whether Cys is exchanged between them has remained enigmatic. This question was addressed using Arabidopsis thaliana T-DNA insertion lines deficient in the final step of Cys biosynthesis catalyzed by the enzyme O-acetylserine(thiol)lyase (OAS-TL). Null alleles of oastlA or oastlB alone showed that cytosolic OAS-TL A and plastid OAS-TL B were completely dispensable, although together they contributed 95% of total OAS-TL activity. An oastlAB double mutant, relying solely on mitochondrial OAS-TL C for Cys synthesis, showed 25% growth retardation. Although OAS-TL C alone was sufficient for full development, oastlC plants also showed retarded growth. Targeted affinity purification identified the major OAS-TL-like proteins. Two-dimensional gel electrophoresis and mass spectrometry showed no compensatory changes of OAS-TL isoforms in the four mutants. Steady state concentrations of Cys and glutathione and pulse-chase labeling with [35S]sulfate indicated strong perturbation of primary sulfur metabolism. These data demonstrate that Cys and also sulfide must be sufficiently exchangeable between cytosol and organelles. Despite partial redundancy, the mitochondria and not the plastids play the most important role for Cys synthesis in Arabidopsis.
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Affiliation(s)
- Corinna Heeg
- Heidelberg Institute of Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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32
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Watanabe M, Kusano M, Oikawa A, Fukushima A, Noji M, Saito K. Physiological roles of the beta-substituted alanine synthase gene family in Arabidopsis. PLANT PHYSIOLOGY 2008; 146:310-20. [PMID: 18024555 PMCID: PMC2230570 DOI: 10.1104/pp.107.106831] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 11/02/2007] [Indexed: 05/18/2023]
Abstract
The beta-substituted alanine (Ala) synthase (Bsas) family in the large superfamily of pyridoxal 5'-phosphate-dependent enzymes comprises cysteine (Cys) synthase (CSase) [O-acetyl-serine (thiol) lyase] and beta-cyano-Ala synthase (CASase) in plants. Nine genomic sequences encode putative Bsas proteins in Arabidopsis thaliana. The physiological roles of these Bsas isoforms in vivo were investigated by the characterization of T-DNA insertion mutants. Analyses of gene expression, activities of CSase and CASase, and levels of Cys and glutathione in the bsas mutants indicated that cytosolic Bsas1;1, plastidic Bsas2;1, and mitochondrial Bsas2;2 play major roles in Cys biosynthesis. Cytosolic Bsas1;1 has the most dominant contribution both in leaf and root, and mitochondrial Bsas2;2 plays a significant role in root. Mitochondrial Bsas3;1 is a genuine CASase. Nontargeted metabolome analyses of knockout mutants were carried out by a combination of gas chromatography time-of-flight mass spectrometry and capillary electrophoresis time-of-flight mass spectrometry. The level of gamma-glutamyl-beta-cyano-Ala decreased in the mutant bsas3;1, indicating the crucial role of Bsas3;1 in beta-cyano-Ala metabolism in vivo.
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Affiliation(s)
- Mutsumi Watanabe
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
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Han SE, Seo YS, Kim D, Sung SK, Kim WT. Expression of MdCAS1 and MdCAS2, encoding apple beta-cyanoalanine synthase homologs, is concomitantly induced during ripening and implicates MdCASs in the possible role of the cyanide detoxification in Fuji apple (Malus domestica Borkh.) fruits. PLANT CELL REPORTS 2007; 26:1321-31. [PMID: 17333023 DOI: 10.1007/s00299-007-0316-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 02/06/2007] [Accepted: 02/08/2007] [Indexed: 05/14/2023]
Abstract
Fruit ripening involves complex biochemical and physiological changes. Ethylene is an essential hormone for the ripening of climacteric fruits. In the process of ethylene biosynthesis, cyanide (HCN), an extremely toxic compound, is produced as a co-product. Thus, most cyanide produced during fruit ripening should be detoxified rapidly by fruit cells. In higher plants, the key enzyme involved in the detoxification of HCN is beta-cyanoalanine synthase (beta-CAS). As little is known about the molecular function of beta-CAS genes in climacteric fruits, we identified two homologous genes, MdCAS1 and MdCAS2, encoding Fuji apple beta-CAS homologs. The structural features of the predicted polypeptides as well as an in vitro enzyme activity assay with bacterially expressed recombinant proteins indicated that MdCAS1 and MdCAS2 may indeed function as beta-CAS isozymes in apple fruits. RNA gel-blot studies revealed that both MdCAS1 and MdCAS2 mRNAs were coordinately induced during the ripening process of apple fruits in an expression pattern comparable with that of ACC oxidase and ethylene production. The MdCAS genes were also activated effectively by exogenous ethylene treatment and mechanical wounding. Thus, it seems like that, in ripening apple fruits, expression of MdCAS1 and MdCAS2 genes is intimately correlated with a climacteric ethylene production and ACC oxidase activity. In addition, beta-CAS enzyme activity was also enhanced as the fruit ripened, although this increase was not as dramatic as the mRNA induction pattern. Overall, these results suggest that MdCAS may play a role in cyanide detoxification in ripening apple fruits.
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Affiliation(s)
- Sang Eun Han
- Department of Biology, College of Science, Yonsei University, Seoul 120-749, South Korea
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Brzywczy J, Natorff R, Sieńko M, Paszewski A. Multiple fungal enzymes possess cysteine synthase activity in vitro. Res Microbiol 2007; 158:428-36. [PMID: 17482430 DOI: 10.1016/j.resmic.2007.03.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 03/06/2007] [Accepted: 03/06/2007] [Indexed: 11/23/2022]
Abstract
We present evidence that there are at least three Aspergillus nidulans enzymes which catalyze in vitro the reaction of O-acetylserine (OAS) with sulfide forming cysteine. This activity is shared by cysteine synthase (CS) encoded by the cysB gene, homocysteine synthase encoded by cysD and by at least one more enzyme. Moreover, arginine, histidine or proline starvation leads to derepression of CS activity even in the cysB,cysD double mutant strains, while neither cysB nor cysD gene transcription is derepressed by amino acid starvation. Using a cpcA mutant, we show that starvation-inducible CS activity is under control of cross-pathway regulation. We identify CysF as a putative CS in A. nidulans. However, cysF gene transcription is not elevated by amino acid starvation. Therefore, it seems that there exists yet another enzyme, thus far unidentified, which possesses CS activity. Using mutants impaired during various steps of cysteine synthesis we prove that the cysB-encoded enzyme is the only CS of physiological importance in the studied fungus. Similar results were obtained with Schizosaccharomyces pombe mutant strains impaired in cysteine synthesis, indicating that the presence of multiple enzymes with in vitro CS activity may be a common feature of many fungal species.
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Affiliation(s)
- Jerzy Brzywczy
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego Street, 02-106 Warszawa, Poland.
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Ogunlabi OO, Agboola FK. A soluble beta-cyanoalanine synthase from the gut of the variegated grasshopper Zonocerus variegatus (L.). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2007; 37:72-9. [PMID: 17175447 DOI: 10.1016/j.ibmb.2006.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Revised: 10/15/2006] [Accepted: 10/23/2006] [Indexed: 05/13/2023]
Abstract
Beta-cyanoalanine synthase (beta-cyano-l-alanine synthase; l-cysteine: hydrogen sulphide lyase (adding hydrogen cyanide (HCN)); EC 4. 4.1.9) was purified from the cytosolic fraction of the gut of grasshopper Zonocerus variegatus (L.) by ion-exchange chromatography on DEAE-Cellulose and gel filtration on Sephadex G-100 columns. The crude enzyme had a specific activity of 2.16nmol H2S/min/mg. A purified enzyme with a specific activity, which was seventeen times higher than that of the crude extract, was obtained. A molecular weight of about 55.23+/-1.00Kd was estimated from its elution volume on Sephadex G-100. The fraction when subjected to sodium dodecyl sulphate-polyacrylamide elel electrophoresis revealed the presence of a protein band with Mr of 23.25+/-0.25Kd. The enzyme exhibited Michaelis-Menten kinetics having Km of 0.38mM for l-cysteine and Km of 6.25mM for cyanide. The optimum temperature and pH for activity were determined to be at 30 degrees C and pH 9.0, respectively. This enzyme might be responsible for the ability to detoxify cyanide in this insect pest and hence its tolerance of the cyanogenic cassava plant. Biophysical, biochemical and kinetic properties of this enzyme, which will reveal how this ability can possibly be compromised by enzyme inhibition, may lead, in the long term, to the potential use of this enzyme as drug target for pest control.
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Piotrowski M, Volmer JJ. Cyanide metabolism in higher plants: cyanoalanine hydratase is a NIT4 homolog. PLANT MOLECULAR BIOLOGY 2006; 61:111-22. [PMID: 16786295 DOI: 10.1007/s11103-005-6217-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2005] [Accepted: 12/23/2005] [Indexed: 05/08/2023]
Abstract
Cyanoalanine hydratase (E.C. 4.2.1.65) is an enzyme involved in the cyanide detoxification pathway of higher plants and catalyzes the hydrolysis of beta-cyano-L-alanine to asparagine. We have isolated the enzyme from seedlings of blue lupine (Lupinus angustifolius) to obtain protein sequence information for molecular cloning. In contrast to earlier reports, extracts of blue lupine cotyledons were found also to contain cyanoalanine-nitrilase (E.C. 3.5.5.4) activity, resulting in aspartic acid production. Both activities co-elute during isolation of cyanoalanine hydratase and are co-precipitated by an antibody directed against Arabidopsis thaliana nitrilase 4 (NIT4). The isolated cyanoalanine hydratase was sequenced by nanospray-MS/MS and shown to be a homolog of Arabidopsis thaliana and Nicotiana tabacum NIT4. Full-length cDNA sequences for two NIT4 homologs from blue lupine were obtained by PCR using degenerate primers and RACE-experiments. The recombinant LaNIT4 enzymes, like Arabidopsis NIT4, hydrolyze cyanoalanine to asparagine and aspartic acid but show a much higher cyanoalanine-hydratase activity. The two nitrilase genes displayed differential but overlapping expression. Taken together these data show that the so-called 'cyanoalanine hydratase' of plants is not a bacterial type nitrile hydratase enzyme but a nitrilase enzyme which can have a remarkably high nitrile-hydratase activity.
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Noji M, Goulart Kawashima C, Obayashi T, Saito K. In silico assessment of gene function involved in cysteine biosynthesis in Arabidopsis: expression analysis of multiple isoforms of serine acetyltransferase. Amino Acids 2006; 30:163-71. [PMID: 16525754 DOI: 10.1007/s00726-005-0253-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Accepted: 07/05/2005] [Indexed: 10/24/2022]
Abstract
In plants, the inorganic sulfur is first fixed into cysteine by the cysteine biosynthetic pathway. This biosynthetic pathway of cysteine involves several enzymatic reactions. In Arabidopsis thaliana, multiple isoforms seem to participate in each enzymatic step for cysteine biosynthesis. To obtain more insights on the specific role of each isoform involved in the cysteine biosynthesis, in silico analysis of these isoforms using Arabidopsis expressed sequence tags (EST) database was carried out. This EST database analysis revealed distinct population distribution of ESTs among multiple isoforms, suggesting that each isoform has its particular expression pattern, presumably associated with its specific role in cysteine biosynthesis. As another in silico analysis, co-expression analysis of genes involved in sulfur metabolism in Arabidopsis was performed using a public transcriptome database of DNA microarrays. This co-expression analysis also suggested specific function and co-regulation of some isoform genes for cysteine biosynthesis by consideration on the clustering of co-expressed genes. From the results of sensitivity to feedback regulation, subcellular localization and expression of mRNA analyses, each serine acetyltransferase (SATase) isoform seems to have its specific role for cysteine biosynthesis. Similar expression patterns were observed between the experimental results of expression data for SATase isoforms and the in silico results of "digital northern" analysis using EST database.
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Affiliation(s)
- M Noji
- Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Inage-ku, Chiba, Japan
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Abstract
Resolution and analysis of genes encoding components of the pathways of primary sulphur assimilation have provided the potential to elucidate how sulphur is managed by plants. Individual roles for members of gene families and regulatory mechanisms operating at gene, cellular and whole plant levels have been recognized. Sulphur is taken up and transported around the plant principally as sulphate, catalysed for the most part by a single gene family of highly regulated transporters. Additional regulation occurs in the pathway of reduction of sulphate to sulphide and its incorporation into cysteine, which occurs principally within the plastid. Cellular and whole-plant regulation of uptake, and the assimilatory pathway attempt to balance supply with demand for growth and include mechanisms for re-mobilization and redistribution of sulphur. Furthermore, optimization of sulphur assimilation requires coordination with carbon and nitrogen pathways, and multiple processes have been proposed to contribute to this balance. Present studies on cis and trans elements are focusing on transcriptional regulation, but this regulation still needs to be linked to apparent metabolite sensing. Whilst the components of the assimilatory pathways have been resolved after many years of controversy, uncertainties remain concerning roles of individual genes in gene families, their sub-cellular localization and their significance in balancing sulphur flux to sulphur demand of the plant for growth under variable environmental conditions.
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Affiliation(s)
- Malcolm J Hawkesford
- Crop Performance and Improvement Division, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.
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Wirtz M, Hell R. Functional analysis of the cysteine synthase protein complex from plants: structural, biochemical and regulatory properties. JOURNAL OF PLANT PHYSIOLOGY 2006; 163:273-86. [PMID: 16386330 DOI: 10.1016/j.jplph.2005.11.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 11/29/2005] [Accepted: 11/30/2005] [Indexed: 05/05/2023]
Abstract
Cysteine synthesis in plants represents the final step of assimilatory sulfate reduction and the almost exclusive entry reaction of reduced sulfur into metabolism not only of plants, but also the human food chain in general. It is accomplished by the sequential reaction of two enzymes, serine acetyltransferase (SAT) and O-acetylserine (thiol) lyase (OAS-TL). Together they form the hetero-oligomeric cysteine synthase complex (CSC). Recent evidence is reviewed that identifies the dual function of the CSC as a sensor and as part of a regulatory circuit that controls cellular sulfur homeostasis. Computational modeling of three-dimensional structures of plant SAT and OAS-TL based on the crystal structure of the corresponding bacterial enzymes supports quaternary conformations of SAT as a dimer of trimers and OAS-TL as a homodimer. These findings suggest an overall alpha6beta4 structure of the subunits of the plant CSC. Kinetic measurements of CSC dissociation triggered by the reaction intermediate O-acetylserine as well as CSC stabilization by sulfide indicate quantitative reactions that are suited to fine-tune the equilibrium between free and associated CSC subunits. In addition, in vitro data show that SAT requires binding to OAS-TL for full activity, while at the same time bound OAS-TL becomes inactivated. Since OAS concentrations inside cells increase upon sulfate deficiency, whereas sulfide concentrations most likely decrease, these data suggest the dissociation of the CSC in vivo, accompanied by inactivation of SAT and activation of OAS-TL function in their free homo-oligomer states. Biochemical evidence describes this protein-interaction based mechanism as reversible, thus closing the regulatory circuit. The properties of the CSC and its subunits are therefore consistent with models of positive regulation of sulfate uptake and reduction in plants by OAS as well as a demand-driven repression/de-repression by a sulfur intermediate, such as sulfide.
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Affiliation(s)
- Markus Wirtz
- Heidelberg Institute of Plant Sciences (HIP), University of Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany
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Wirtz M, Droux M. Synthesis of the sulfur amino acids: cysteine and methionine. PHOTOSYNTHESIS RESEARCH 2005; 86:345-62. [PMID: 16307301 DOI: 10.1007/s11120-005-8810-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Accepted: 06/15/2005] [Indexed: 05/05/2023]
Abstract
This review will assess new features reported for the molecular and biochemical aspects of cysteine and methionine biosynthesis in Arabidopsis thaliana with regards to early published data from other taxa including crop plants and bacteria (Escherichia coli as a model). By contrast to bacteria and fungi, plant cells present a complex organization, in which the sulfur network takes place in multiple sites. Particularly, the impact of sulfur amino-acid biosynthesis compartmentalization will be addressed in respect to localization of sulfur reduction. To this end, the review will focus on regulation of sulfate reduction by synthesis of cysteine through the cysteine synthase complex and the synthesis of methionine and its derivatives. Finally, regulatory aspects of sulfur amino-acid biosynthesis will be explored with regards to interlacing processes such as photosynthesis, carbon and nitrogen assimilation.
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Affiliation(s)
- Markus Wirtz
- Heidelberg Institute of Plant Sciences (HIP), University of Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany.
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Riemenschneider A, Riedel K, Hoefgen R, Papenbrock J, Hesse H. Impact of reduced O-acetylserine(thiol)lyase isoform contents on potato plant metabolism. PLANT PHYSIOLOGY 2005; 137:892-900. [PMID: 15728339 PMCID: PMC1065390 DOI: 10.1104/pp.104.057125] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2004] [Revised: 01/03/2005] [Accepted: 01/03/2005] [Indexed: 05/20/2023]
Abstract
Plant cysteine (Cys) synthesis can occur in three cellular compartments: the chloroplast, cytoplasm, and mitochondrion. Cys formation is catalyzed by the enzyme O-acetylserine(thiol)lyase (OASTL) using O-acetylserine (OAS) and sulfide as substrates. To unravel the function of different isoforms of OASTL in cellular metabolism, a transgenic approach was used to down-regulate specifically the plastidial and cytosolic isoforms in potato (Solanum tuberosum). This approach resulted in decreased RNA, protein, and enzymatic activity levels. Intriguingly, H(2)S-releasing capacity was also reduced in these lines. Unexpectedly, the thiol levels in the transgenic lines were, regardless of the selected OASTL isoform, significantly elevated. Furthermore, levels of metabolites such as serine, OAS, methionine, threonine, isoleucine, and lysine also increased in the investigated transgenic lines. This indicates that higher Cys levels might influence methionine synthesis and subsequently pathway-related amino acids. The increase of serine and OAS points to suboptimal Cys synthesis in transgenic plants. Taking these findings together, it can be assumed that excess OASTL activity regulates not only Cys de novo synthesis but also its homeostasis. A model for the regulation of Cys levels in plants is proposed.
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Galili G, Amir R, Hoefgen R, Hesse H. Improving the levels of essential amino acids and sulfur metabolites in plants. Biol Chem 2005; 386:817-31. [PMID: 16164407 DOI: 10.1515/bc.2005.097] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractPlants represent the major source of food for humans, either directly or indirectly through their use as livestock feeds. Plant foods are not nutritionally balanced because they contain low proportions of a number of essential metabolites, such as vitamins and amino acids, which humans and a significant proportion of their livestock cannot produce on their own. Among the essential amino acids needed in human diets, Lys, Met, Thr and Trp are considered as the most important because they are present in only low levels in plant foods. In the present review, we discuss approaches to improve the levels of the essential amino acids Lys and Met, as well as of sulfur metabolites, in plants using metabolic engineering approaches. We also focus on specific examples for which a deeper understanding of the regulation of metabolic networks in plants is needed for tailor-made improvements of amino acid metabolism with minimal interference in plant growth and productivity.
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Affiliation(s)
- Gad Galili
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
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Kawashima CG, Berkowitz O, Hell R, Noji M, Saito K. Characterization and expression analysis of a serine acetyltransferase gene family involved in a key step of the sulfur assimilation pathway in Arabidopsis. PLANT PHYSIOLOGY 2005; 137:220-30. [PMID: 15579666 PMCID: PMC548853 DOI: 10.1104/pp.104.045377] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2004] [Revised: 06/15/2004] [Accepted: 06/18/2004] [Indexed: 05/20/2023]
Abstract
Ser acetyltransferase (SATase; EC 2.3.1.30) catalyzes the formation of O-acetyl-Ser from L-Ser and acetyl-CoA, leading to synthesis of Cys. According to its position at the decisive junction of the pathways of sulfur assimilation and amino acid metabolism, SATases are subject to regulatory mechanisms to control the flux of Cys synthesis. In Arabidopsis (Arabidopsis thaliana) there are five genes encoding SATase-like proteins. Two isoforms, Serat3;1 and Serat3;2, were characterized with respect to their enzymatic properties, feedback inhibition by L-Cys, and subcellular localization. Functional identity of Serat3;1 and Serat3;2 was established by complementation of a SATase-deficient mutant of Escherichia coli. Cytosolic localization of Serat3;1 and Serat3;2 was confirmed by using fusion construct with the green fluorescent protein. Recombinant Serat3;1 was not inhibited by L-Cys, while Serat3;2 was a strongly feedback-inhibited isoform. Quantification of expression patterns indicated that Serat2;1 is the dominant form expressed in most tissues examined, followed by Serat1;1 and Serat2;2. Although Serat3;1 and Serat3;2 were expressed weakly in most tissues, Serat3;2 expression was significantly induced under sulfur deficiency and cadmium stress as well as during generative developmental stages, implying that Serat3;1 and Serat3;2 have specific roles when plants are subjected to distinct conditions. Transgenic Arabidopsis plants expressing the green fluorescent protein under the control of the five promoters indicated that, in all Serat genes, the expression was predominantly localized in the vascular system, notably in the phloem. These results demonstrate that Arabidopsis employs a complex array of compartment-specific SATase isoforms with distinct enzymatic properties and expression patterns to ensure the provision of Cys in response to developmental and environmental changes.
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Affiliation(s)
- Cintia Goulart Kawashima
- Department of Molecular Biology and Biotechnology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
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Hesse H, Nikiforova V, Gakière B, Hoefgen R. Molecular analysis and control of cysteine biosynthesis: integration of nitrogen and sulphur metabolism. JOURNAL OF EXPERIMENTAL BOTANY 2004; 55:1283-92. [PMID: 15133050 DOI: 10.1093/jxb/erh136] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Since cysteine is the first committed molecule in plant metabolism containing both sulphur and nitrogen, the regulation of its biosynthesis is critically important. Cysteine itself is required for the production of an abundance of key metabolites in diverse pathways. Plants alter their metabolism to compensate for sulphur and nitrogen deficiencies as best as they can, but limitations in either nutrient not only curb a plant's ability to synthesize cysteine, but also restrict protein synthesis. Nutrients such as nitrate and sulphate (and carbon) act as signals; they trigger molecular mechanisms that modify biosynthetic pathways and thereby have a profound impact on metabolite fluxes. Cysteine biosynthesis is modified by regulators acting at the site of uptake and throughout the plant system. Recent data point to the existence of nutrient-specific signal transduction pathways that relay information about external and internal nutrient concentrations, resulting in alterations to cysteine biosynthesis. Progress in this field has led to the cloning of genes that play pivotal roles in nutrient-induced changes in cysteine formation.
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Affiliation(s)
- Holger Hesse
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department of Molecular Physiology, Am Muehlenberg 1, D-14476 Golm, Germany.
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Brenner ED, Stevenson DW, McCombie RW, Katari MS, Rudd SA, Mayer KFX, Palenchar PM, Runko SJ, Twigg RW, Dai G, Martienssen RA, Benfey PN, Coruzzi GM. Expressed sequence tag analysis in Cycas, the most primitive living seed plant. Genome Biol 2003; 4:R78. [PMID: 14659015 PMCID: PMC329417 DOI: 10.1186/gb-2003-4-12-r78] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Revised: 10/03/2003] [Accepted: 10/23/2003] [Indexed: 11/10/2022] Open
Abstract
Analysis of cycad ESTs has uncovered conserved and potentially novel genes. The presence of a glutamate receptor agonist, as well as a glutamate receptor-like gene in cycads, supports the hypothesis that such neuroactive plant products are not merely herbivore deterrents but may also serve a role in plant signaling. Background Cycads are ancient seed plants (living fossils) with origins in the Paleozoic. Cycads are sometimes considered a 'missing link' as they exhibit characteristics intermediate between vascular non-seed plants and the more derived seed plants. Cycads have also been implicated as the source of 'Guam's dementia', possibly due to the production of S(+)-beta-methyl-alpha, beta-diaminopropionic acid (BMAA), which is an agonist of animal glutamate receptors. Results A total of 4,200 expressed sequence tags (ESTs) were created from Cycas rumphii and clustered into 2,458 contigs, of which 1,764 had low-stringency BLAST similarity to other plant genes. Among those cycad contigs with similarity to plant genes, 1,718 cycad 'hits' are to angiosperms, 1,310 match genes in gymnosperms and 734 match lower (non-seed) plants. Forty-six contigs were found that matched only genes in lower plants and gymnosperms. Upon obtaining the complete sequence from the clones of 37/46 contigs, 14 still matched only gymnosperms. Among those cycad contigs common to higher plants, ESTs were discovered that correspond to those involved in development and signaling in present-day flowering plants. We purified a cycad EST for a glutamate receptor (GLR)-like gene, as well as ESTs potentially involved in the synthesis of the GLR agonist BMAA. Conclusions Analysis of cycad ESTs has uncovered conserved and potentially novel genes. Furthermore, the presence of a glutamate receptor agonist, as well as a glutamate receptor-like gene in cycads, supports the hypothesis that such neuroactive plant products are not merely herbivore deterrents but may also serve a role in plant signaling.
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Affiliation(s)
- Eric D Brenner
- The New York Botanical Garden, 200th Street and Kazimiroff, Bronx, NY 10458-5126, USA.
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Meyer T, Burow M, Bauer M, Papenbrock J. Arabidopsis sulfurtransferases: investigation of their function during senescence and in cyanide detoxification. PLANTA 2003; 217:1-10. [PMID: 12721843 DOI: 10.1007/s00425-002-0964-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2002] [Accepted: 11/25/2002] [Indexed: 05/21/2023]
Abstract
Sulfurtransferases (STs) and beta-cyano- l-alanine synthase (CAS) are suggested to be involved in cyanide detoxification. Therefore, the accumulation of ST1 and CAS RNAs, and the ST and CAS protein levels and enzyme activities were determined in Arabidopsis thaliana Heynh. plants grown under different conditions. Senescence-associated processes were successfully induced by natural aging, by jasmonate methyl ester and by darkness in whole plants and detached leaves, as demonstrated by the expression of the senescence marker genes SAG12 and SAG13. However, the changes in RNA accumulation and protein levels of ST and CAS did not correlate with the expression of these senescence marker genes; the specific ST and CAS activities either decreased (ST) or increased (CAS). In another experiment, Arabidopsis plants were sprayed with cyanide to investigate the role of ST and CAS in cyanide detoxification. The expression of ST and CAS at the RNA and protein levels, and also the enzyme activities, remained equal in cyanide-treated and control plants. Incubation with 1-aminocyclopropane-1-carboxylic acid, the precursor of ethylene, increased while fumigation with ethylene decreased expression and activity of ST and CAS. In summary, cyanide does not induce the expression or enhance the activity of ST and CAS in Arabidopsis. For both proteins the evidence for a role in cyanide detoxification or induced senescence is low.
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Affiliation(s)
- Tanja Meyer
- Institute for Botany, University of Hannover, Herrenhäuserstr. 2, 30419, Hannover, Germany
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Berkowitz O, Wirtz M, Wolf A, Kuhlmann J, Hell R. Use of biomolecular interaction analysis to elucidate the regulatory mechanism of the cysteine synthase complex from Arabidopsis thaliana. J Biol Chem 2002; 277:30629-34. [PMID: 12063244 DOI: 10.1074/jbc.m111632200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Real time biomolecular interaction analysis based on surface plasmon resonance has been proven useful for studying protein-protein interaction but has not been extended so far to investigate enzyme-enzyme interactions, especially as pertaining to regulation of metabolic activity. We have applied BIAcore technology to study the regulation of enzyme-enzyme interaction during mitochondrial cysteine biosynthesis in Arabidopsis thaliana. The association of the two enzyme subunits in the hetero-oligomeric cysteine synthase complex was investigated with respect to the reaction intermediate and putative effector O-acetylserine. We have determined an equilibrium dissociation constant of the cysteine synthase complex (K(D) = 25 +/- 4 x 10(-9) m), based on a reliable A + B <--> AB model of interaction. Analysis of dissociation kinetics in the presence of O-acetylserine revealed a half-maximal dissociation rate at 77 +/- 4 microm O-acetylserine and strong positive cooperativity for complex dissociation. The equilibrium of interaction was determined using an enzyme activity-based approach and yielded a K(m) value of 58 +/- 7 microm O-acetylserine. Both effector concentrations are in the range of intracellular O-acetylserine fluctuations and support a functional model that integrates effector-driven cysteine synthase complex dissociation as a regulatory switch for the biosynthetic pathway. The results show that BIAcore technology can be applied to obtain quantitative kinetic data of a hetero-oligomeric protein complex with enzymatic and regulatory function.
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Affiliation(s)
- Oliver Berkowitz
- Institute for Plant Genetics and Crop Plant Research (IPK), Dept. Molecular Cell Biology, Corrensstrasse 3, 06466 Gatersleben, Germany
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Warrilow AGS, Hawkesford MJ. Modulation of cyanoalanine synthase and O-acetylserine (thiol) lyases A and B activity by beta-substituted alanyl and anion inhibitors. JOURNAL OF EXPERIMENTAL BOTANY 2002; 53:439-445. [PMID: 11847242 DOI: 10.1093/jexbot/53.368.439] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The reaction mechanisms of three enzymes belonging to a single gene family are compared: a cyanoalanine synthase and two isoforms of O-acetylserine (thiol) lyase (O-ASTL) isolated from spinach (Spinacea oleracea L. cv. Medina). O-ASTL represents a major regulatory point in the S-assimilatory pathway, and the related cyanoalanine synthase, which is specific to the mitochondrial compartment, has evolved an independent function of cyanide detoxification. All three enzymes catalysed both the cysteine synthesis and cyanoalanine synthesis reactions although with different efficiencies, and which may be explained by a single amino acid substitution in the substrate-binding pocket of the enzyme. Substituted alanine and nucleophillic inhibitors caused predominantly non-competitive inhibition, indicating binding to both E- and F-forms of the enzyme in a bi-bi ping-pong kinetic model. Michaelis-Menten kinetics were observed when the alanyl substrate was varied in the presence and absence of inhibitors. The use of alanyl inhibitors has shown that the alanyl half-cycle of both the cysteine synthesis and cyanoalanine synthesis reactions of cyanoalanine synthase and O-acetylserine (thiol) lyases are similar. This is in contrast to the results observed with nucleophillic inhibitors, which have shown that the mechanisms of anion binding and processing differ between cyanoalanine synthase and O-ASTLs.
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Affiliation(s)
- Andrew G S Warrilow
- IACR-Rothamsted, Agriculture and Environment Division, Harpenden, Hertfordshire AL5 2JQ, UK
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Affiliation(s)
- Thomas Leustek
- Biotechnology Center for Agriculture and the Environment, Plant Science Department, 59 Dudley Road, Rutgers University, New Brunswick, New Jersey 08901-8520, USA, tel: (732)932-8165, ext 326, fax: (732)932-0312,
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Jost R, Berkowitz O, Wirtz M, Hopkins L, Hawkesford MJ, Hell R. Genomic and functional characterization of the oas gene family encoding O-acetylserine (thiol) lyases, enzymes catalyzing the final step in cysteine biosynthesis in Arabidopsis thaliana. Gene 2000; 253:237-47. [PMID: 10940562 DOI: 10.1016/s0378-1119(00)00261-4] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The final step of cysteine biosynthesis in plants is catalyzed by O-acetylserine (thiol) lyase (OAS-TL), which occurs as several isoforms found in the cytosol, the plastids and the mitochondria. Genomic DNA blot hybridization and isolation of genomic clones indicate single copy genes (oasA1, oasA2, oasB and oasC) that encode the activities of OAS-TL A, B and C found in separate subcellular compartments in the model plant Arabidopsis thaliana. Sequence analysis reveals that the newly discovered oasA2 gene represents a pseudogene that is still transcribed, but is not functionally translated. The comparison of gene structures suggests that oasA1/oasA2 and oasB/oasC are closely related and may be derived from a common ancestor by subsequent duplications. OAS-TL A, B and C were overexpressed in an Escherichia coli mutant lacking cysteine synthesis and exhibited bifunctional OAS-TL and beta-cyanoalanine synthase (CAS) activities. However, all three proteins represent true OAS-TLs according to kinetic analysis and are unlikely to function in cyanide detoxification or secondary metabolism. In addition, it was demonstrated that the mitochondrial OAS-TL C exhibits in vivo protein-protein interaction capabilities with respect to cysteine synthase complex formation similar to cytosolic OAS-TL A and plastid OAS-TL B. Multiple database accessions for each of the A. thaliana OAS-TL isoforms can thus be attributed to a specified number of oas genes to which functionally defined gene products are assigned, and which are responsible for compartment-specific cysteine synthesis.
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Affiliation(s)
- R Jost
- Institute for Plant Genetics and Crop Plant Research (IPK), Molecular Cell Biology Department, 06466, Gatersleben, Germany
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