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Zhang J, Zhang X, Jia M, Fu Q, Guo Y, Wang Z, Kong D, Lin Y, Zhao D. Two novel transporters NtNRAMP6a and NtNRAMP6b are involved in cadmium transport in tobacco (Nicotiana tabacum L.). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 202:107953. [PMID: 37572492 DOI: 10.1016/j.plaphy.2023.107953] [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: 04/27/2023] [Revised: 07/15/2023] [Accepted: 08/06/2023] [Indexed: 08/14/2023]
Abstract
Plant natural resistance-associated macrophage protein (NRAMP) plays important roles in metal transport and tolerance. Tobacco is a typical cadmium (Cd) accumulator, while research on NRAMP in tobacco has been limited. In the current study, two novel NRAMP genes (NtNRAMP6a and NtNRAMP6b) were identified from the allotetraploid plant Nicotiana tabacum L. Real time‒PCR and GUS (β-glucuronidase) staining results showed that the two genes were expressed in roots, stems, leaves and flowers and induced by Cd stress. Subcellular localization revealed that they were located in the plasma membrane. Heterologously expressed NtNRAMP6a and NtNRAMP6b significantly increased the Cd sensitivity of the Δycf1 mutant, indicating that NtNRAMP6a and NtNRAMP6b had Cd transport functions in yeast. The difference in the manganese (Mn) transport activity of the two genes was demonstrated by point mutation, which was caused by the difference in the 18th amino acid. NRAMP6-N18K is a new key active site for manganese transport. After 50 μM Cd treatment for 7 days, the contents of Cd and Mn of the ntnramp6a/6b mutants was significantly lower than those of wild type in shoots, while the contents in roots were higher. Additionally, the mutant lines showed higher chorphyll contentration and lighter leaf damage. Knockout of NtNRAMP6a and NtNRAMP6b reduced Cd and Mn accumulation in tobacco shoots by influence root-to-shoot translocation. This provides new idea for cultivating tobacco varieties with low cadmium accumulation and high cadmium tolerance.
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Affiliation(s)
- Jishun Zhang
- Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guizhou Key Laboratory of Agro-Bioengineering, Institute of Agro-Bioengineering / College of Life Sciences, Guizhou University, Guiyang 550025, China; Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China
| | - Xiaolian Zhang
- Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China
| | - Mengao Jia
- Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China
| | - Qiang Fu
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
| | - Yushuang Guo
- Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China
| | - Zhihong Wang
- Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China
| | - Dejun Kong
- Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China
| | - Yingchao Lin
- Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China
| | - Degang Zhao
- Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guizhou Key Laboratory of Agro-Bioengineering, Institute of Agro-Bioengineering / College of Life Sciences, Guizhou University, Guiyang 550025, China; Guizhou Plant Conservation Technology Center, Guizhou Key Laboratory of Agricultural Biotechnology, Guizhou Academy of Agricultural Sciences, Guiyang 550006, China.
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Ajeesh Krishna TP, Maharajan T, Antony Ceasar S. Significance and genetic control of membrane transporters to improve phytoremediation and biofortification processes. Mol Biol Rep 2023:10.1007/s11033-023-08521-2. [PMID: 37212961 DOI: 10.1007/s11033-023-08521-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 05/11/2023] [Indexed: 05/23/2023]
Abstract
Humans frequently consume plant-based foods in their daily life. Contamination of agricultural soils by heavy metals (HMs) is a major food and nutritional security issue. The crop plants grown in HM-contaminated agricultural soil may accumulate more HMs in their edible part, further transferring into the food chain. Consumption of HM-rich crops can cause severe health issues in humans. On the other hand, the low content of the essential HM in the edible part of the crop also causes health problems. Therefore, researchers must try to reduce the non-essential HM in the edible part of the crop plants and improve the essential HMs. Phytoremediation and biofortification are the two strategies for resolving this problem. The genetic component helps to improve the efficiency of phytoremediation and biofortification processes in plants. They help eliminate HMs from soil and improve essential HM content in crop plants. The membrane transporter genes (genetic components) are critical in these two strategies. Therefore, engineering membrane transporter genes may help reduce the non-essential HM content in the edible part of crop plants. Targeted gene editing by genome editing tools like CRISPR could help plants achieve efficient phytoremediation and biofortification. This article covers gene editing's scope, application, and implication to improve the phytoremediation and biofortification processes in non-crop and crop plants.
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Affiliation(s)
- T P Ajeesh Krishna
- Division of Plant Molecular Biology and Biotechnology, Department of Biosciences, Rajagiri College of Social Sciences, Kochi, Kerala, 683104, India
| | - Theivanayagam Maharajan
- Division of Plant Molecular Biology and Biotechnology, Department of Biosciences, Rajagiri College of Social Sciences, Kochi, Kerala, 683104, India
| | - S Antony Ceasar
- Division of Plant Molecular Biology and Biotechnology, Department of Biosciences, Rajagiri College of Social Sciences, Kochi, Kerala, 683104, India.
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3
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Hu J, Chang R, Yuan Y, Li Z, Wang Y. Identification of Key Residues Essential for the Activation of Plant Immunity by Subtilisin From Bacillus velezensis LJ02. Front Microbiol 2022; 13:869596. [PMID: 36046019 PMCID: PMC9421249 DOI: 10.3389/fmicb.2022.869596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 06/17/2022] [Indexed: 11/13/2022] Open
Abstract
Subtilisin, a serine protease, can trigger defense responses in a wide variety of plants, both locally and systemically, to protect against pathogens. However, key residues of subtilisin to improve resistance to plant diseases remain unknown. In this study, Nicotiana benthamiana (N. benthamiana) leaves expressing subtilisin from Bacillus velezensis LJ02 were shown to improve protection against Botrytis cinerea (B. cinerea). Furthermore, the underlying mechanism that LJ02 subtilisin improved the protective effect was explored, and the direct inhibitory effect of subtilisin on B. cinerea was excluded in vitro. Subsequently, reactive oxygen species (ROS) burst and upregulation of resistance-related genes in systemic leaves of N. benthamiana further verified that subtilisin could induce systemic protection against B. cinerea. G307A/T308A and S213A/L214A/G215A subtilisin significantly reduced the ability to resist B. cinerea infection in N. benthamiana. Furthermore, the ROS content and expression levels of resistance-related genes of both mutants were significantly decreased compared with that of wild-type subtilisin. This work identified key residues essential for the activation function of subtilisin plant immunity and was crucial in inducing plant defense responses against B. cinerea.
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Affiliation(s)
- Jianan Hu
- College of Horticulture and Landscape Architecture, Tianjin Agricultural University, Tianjin, China
| | - Ruokui Chang
- College of Engineering and Technology, Tianjin Agricultural University, Tianjin, China
| | - Yujin Yuan
- College of Horticulture and Landscape Architecture, Tianjin Agricultural University, Tianjin, China
| | - Zhuoran Li
- College of Horticulture and Landscape Architecture, Tianjin Agricultural University, Tianjin, China
- Zhuoran Li,
| | - Yuanhong Wang
- College of Horticulture and Landscape Architecture, Tianjin Agricultural University, Tianjin, China
- *Correspondence: Yuanhong Wang,
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4
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Advances in Genes-Encoding Transporters for Cadmium Uptake, Translocation, and Accumulation in Plants. TOXICS 2022; 10:toxics10080411. [PMID: 35893843 PMCID: PMC9332107 DOI: 10.3390/toxics10080411] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/15/2022] [Accepted: 07/20/2022] [Indexed: 12/12/2022]
Abstract
Cadmium (Cd) is a heavy metal that is highly toxic for plants, animals, and human beings. A better understanding of the mechanisms involved in Cd accumulation in plants is beneficial for developing strategies for either the remediation of Cd-polluted soils using hyperaccumulator plants or preventing excess Cd accumulation in the edible parts of crops and vegetables. As a ubiquitous heavy metal, the transport of Cd in plant cells is suggested to be mediated by transporters for essential elements such as Ca, Zn, K, and Mn. Identification of the genes encoding Cd transporters is important for understanding the mechanisms underlying Cd uptake, translocation, and accumulation in either crop or hyperaccumulator plants. Recent studies have shown that the transporters that mediate the uptake, transport, and accumulation of Cd in plants mainly include members of the natural resistance-associated macrophage protein (Nramp), heavy metal-transporting ATPase (HMA), zinc and iron regulated transporter protein (ZIP), ATP-binding cassette (ABC), and yellow stripe-like (YSL) families. Here, we review the latest advances in the research of these Cd transporters and lay the foundation for a systematic understanding underlying the molecular mechanisms of Cd uptake, transport, and accumulation in plants.
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Hafsi C, Collado-Arenal AM, Wang H, Sanz-Fernández M, Sahrawy M, Shabala S, Romero-Puertas MC, Sandalio LM. The role of NADPH oxidases in regulating leaf gas exchange and ion homeostasis in Arabidopsis plants under cadmium stress. JOURNAL OF HAZARDOUS MATERIALS 2022; 429:128217. [PMID: 35077969 DOI: 10.1016/j.jhazmat.2022.128217] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/23/2021] [Accepted: 01/02/2022] [Indexed: 06/14/2023]
Abstract
NADPH oxidase, an enzyme associated with the plasma membrane, constitutes one of the main sources of reactive oxygen species (ROS) which regulate different developmental and adaptive responses in plants. In this work, the involvement of NADPH oxidases in the regulation of photosynthesis and cell ionic homeostasis in response to short cadmium exposure was compared between wild type (WT) and three RBOHs (Respiratory Burst Oxidase Homologues) Arabidopsis mutants (AtrbohC, AtrbohD, and AtrbohF). Plants were grown under hydroponic conditions and supplemented with 50 µM CdCl2 for 24 h. Cadmium treatment differentially affected photosynthesis, stomatal conductance, transpiration, and antioxidative responses in WT and Atrbohs mutants. The loss of function of RBOH isoforms resulted in higher Cd2+ influx, mainly in the elongation zone of roots, which was more evident in AtrbohD and AtrbohF mutants. In the mature zone, the highest Cd2+ influx was observed in rbohC mutant. The lack of functional RBOH isoforms also resulted in altered patterns of net K+ transport across cellular membranes, both in the root epidermis and leaf mesophyll. The analysis of expression of metal transporters by qPCR demonstrated that a loss of functional RBOH isoforms has altered transcript levels for metal NRAMP3, NRAMP6 and IRT1 and the K+ transporters outward-rectifying K+ efflux GORK channel, while RBOHD specifically regulated transcripts for high-affinity K+ transporters KUP8 and HAK5, and IRT1 and RBOHD and F regulated the transcription factors TGA3 and TGA10. It is concluded that RBOH-dependent H2O2 regulation of ion homeostasis and Cd is a highly complex process involving multilevel regulation from transpirational water flow to transcriptional and posttranslational modifications of K/metals transporters.
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Affiliation(s)
- Chokri Hafsi
- Laboratory of Extremophile Plants, Centre of Biotechnology of Borj-Cedria, P. O. Box 901 - 2050, Hammam-Lif, Tunisia; Higher Institute of Biotechnology of Beja (ISBB), University of Jendouba, Habib Bourguiba avenue P. O. Box 382 - 9000, Beja, Tunisia
| | - Aurelio M Collado-Arenal
- Department of Plant Biochemistry, Cellular and Molecular Biology. Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Haiyang Wang
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - María Sanz-Fernández
- Department of Plant Biochemistry, Cellular and Molecular Biology. Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Mariam Sahrawy
- Department of Plant Biochemistry, Cellular and Molecular Biology. Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania 7001, Australia; International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China
| | - María C Romero-Puertas
- Department of Plant Biochemistry, Cellular and Molecular Biology. Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain
| | - Luisa M Sandalio
- Department of Plant Biochemistry, Cellular and Molecular Biology. Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain.
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Metalloprotein-Specific or Critical Amino Acid Residues: Perspectives on Plant-Precise Detoxification and Recognition Mechanisms under Cadmium Stress. Int J Mol Sci 2022; 23:ijms23031734. [PMID: 35163656 PMCID: PMC8836122 DOI: 10.3390/ijms23031734] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/26/2022] [Accepted: 02/02/2022] [Indexed: 12/15/2022] Open
Abstract
Cadmium (Cd) pollution in cultivated land is caused by irresistible geological factors and human activities; intense diffusion and migration have seriously affected the safety of food crops. Plants have evolved mechanisms to control excessive influx of Cd in the environment, such as directional transport, chelation and detoxification. This is done by some specific metalloproteins, whose key amino acid motifs have been investigated by scientists one by one. The application of powerful cell biology, crystal structure science, and molecular probe targeted labeling technology has identified a series of protein families involved in the influx, transport and detoxification of the heavy metal Cd. This review summarizes them as influx proteins (NRAMP, ZIP), chelating proteins (MT, PDF), vacuolar proteins (CAX, ABCC, MTP), long-distance transport proteins (OPT, HMA) and efflux proteins (PCR, ABCG). We selected representative proteins from each family, and compared their amino acid sequence, motif structure, subcellular location, tissue specific distribution and other characteristics of differences and common points, so as to summarize the key residues of the Cd binding target. Then, we explain its special mechanism of action from the molecular structure. In conclusion, this review is expected to provide a reference for the exploration of key amino acid targets of Cd, and lay a foundation for the intelligent design and breeding of crops with high/low Cd accumulation.
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Yue X, Song J, Fang B, Wang L, Zou J, Su N, Cui J. BcNRAMP1 promotes the absorption of cadmium and manganese in Arabidopsis. CHEMOSPHERE 2021; 283:131113. [PMID: 34146878 DOI: 10.1016/j.chemosphere.2021.131113] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 05/29/2021] [Accepted: 05/31/2021] [Indexed: 05/22/2023]
Abstract
Cadmium (Cd) is a toxic nonessential metal that poses a health risk for humans. Cd is easily accumulated in leaf vegetables than in other vegetables. Leafy vegetables are one of the major dietary Cd sources for the human body. In this study, pak choi was used as our experimental material as it is an important leafy vegetable, especially in Asia. A NRAMP transporter - BcNRAMP1 was identified in pak choi, which is involved in manganese (Mn) and Cd uptake in yeast and in planta. BcNRAMP1 is expressed in the whole plant body of pak choi, with a higher abundance in root tissues than in shoots. Mn deficiency and Cd exposure strongly induced BcNRAMP1 transcription levels. Through transient expression of BcNRAMP1-GFP fusion protein in tobacco leaf epidermal cells, BcNRAMP1 was revealed as a plasma membrane protein. Expressing BcNRAMP1 in yeast enhanced yeast cells to absorb Mn, Cd, and iron (Fe). Overexpression of BcNRAMP1 in Arabidopsis wild-type and nramp1 mutant increased and complemented Mn and Cd transportation and accumulation, respectively. Using noninvasive microelectrode ion flux measurements, a direct evidence that BcNRAMP1 acts on Cd influx in Arabidopsis root cells was provided. The results of this study reveal that BcNRAMP1 functions as a NRAMP protein in planta, absorbing nutrient metal Mn and the toxic metal Cd.
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Affiliation(s)
- Xiaomeng Yue
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Jinxue Song
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Bo Fang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Lu Wang
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia.
| | - Jianwen Zou
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Nana Su
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Jin Cui
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
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Zhang H, Lu X, Wang Z, Yan X, Cui H. Excretion from long glandular trichomes contributes to alleviation of cadmium toxicity in Nicotiana tabacum. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 285:117184. [PMID: 33962307 DOI: 10.1016/j.envpol.2021.117184] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/21/2021] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
The B-type cyclin gene, CycB2, serves as a negative regulator of glandular trichome initiation. Through targeted knockout of NtCycB2 in Nicotiana tabacum cv. K326 using the CRISPR/Cas9 system, we created a variety, HK326, which exhibits significantly increased density and larger glandular heads of long glandular trichomes. Under Cd-stress, HK326 exhibited enhanced Cd tolerance, as demonstrated by a robust root system, strengthened cell membrane stability, and higher photosynthetic parameters. HK326 exhibited enhanced Cd-stress tolerance due to a strong excretion capacity of long glandular trichomes by forming calcium oxalate crystals. Cd mainly accumulated in tobacco shoots rather than remained in roots. Specifically, Cd levels of the HK326 shoot surface were nearly two-fold of those of K326, resulting in less Cd internally in the roots and shoots. Gene expression patterns revealed 11 Cd transporter genes that were upregulated after Cd-stress in shoots, roots, and trichomes. Among them, the NtHMA2 gene encoding heavy metal ATPases and involved in the transport of divalent heavy metal cations was expressed consistently and significantly higher in HK326 than K326, both before and after Cd-stress. NtHMA2 expression was strong in trichomes, moderate in shoots, while weak in roots. The results indicate that NtHMA2 may be involved in Cd excretion from glandular trichomes. Our findings suggest HK326 may be an appropriate candidate plant for Cd-stress tolerance.
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Affiliation(s)
- Hongying Zhang
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China
| | - Xinyong Lu
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China
| | - Zhaojun Wang
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China
| | - Xiaoxiao Yan
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China
| | - Hong Cui
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China.
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Molecular Mechanism of Nramp-Family Transition Metal Transport. J Mol Biol 2021; 433:166991. [PMID: 33865868 DOI: 10.1016/j.jmb.2021.166991] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 02/06/2023]
Abstract
The Natural resistance-associated macrophage protein (Nramp) family of transition metal transporters enables uptake and trafficking of essential micronutrients that all organisms must acquire to survive. Two decades after Nramps were identified as proton-driven, voltage-dependent secondary transporters, multiple Nramp crystal structures have begun to illustrate the fine details of the transport process and provide a new framework for understanding a wealth of preexisting biochemical data. Here we review the relevant literature pertaining to Nramps' biological roles and especially their conserved molecular mechanism, including our updated understanding of conformational change, metal binding and transport, substrate selectivity, proton transport, proton-metal coupling, and voltage dependence. We ultimately describe how the Nramp family has adapted the LeuT fold common to many secondary transporters to provide selective transition-metal transport with a mechanism that deviates from the canonical model of symport.
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Huang WX, Zhang DM, Cao YQ, Dang BJ, Jia W, Xu ZC, Han D. Differential cadmium translocation and accumulation between Nicotiana tabacum L. and Nicotiana rustica L. by transcriptome combined with chemical form analyses. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 208:111412. [PMID: 33039872 DOI: 10.1016/j.ecoenv.2020.111412] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 05/17/2023]
Abstract
Cadmium (Cd) is a severely toxic and carcinogenic heavy metal. Cigarette smoking is one of the major source of Cd exposure in humans. Nicotiana tabacum is primarily a leaf Cd accumulator, while Nicotiana rustica is a root Cd accumulator among Nicotiana species. However, little is known about the mechanisms of differential Cd translocation and accumulation in Nicotiana. To find the key factors, Cd concentration, Cd chemical forms, and transcriptome analysis were comparatively studied between N. tabacum and N. rustica under control or 10 μM Cd stress. The leaf/root Cd concentration ratio of N. tabacum was 2.26 and that of N. rustica was 0.14. The Cd concentration in xylem sap of N. tabacum was significantly higher than that of N. rustica. The root of N. tabacum had obviously higher proportion of ethanol extractable Cd (40%) and water extractable Cd (16%) than those of N. rustica (16% and 6%). Meanwhile the proportion of sodium chloride extracted Cd in N. rustica (71%) was significantly higher than that in N. tabacum (30%). A total of 30710 genes expressed differentially between the two species at control, while this value was 30,294 under Cd stress, among which 27,018 were collective genes, manifesting the two species existed enormous genetic differences. KEGG pathway analysis showed the phenylpropanoid biosynthesis pathway was overrepresented between the two species under Cd stress. Several genes associated with pectin methylesterase, suberin and lignin synthesis, and heavy metal transport were discovered to be differential expressed genes between two species. The results suggested that the higher accumulation of Cd in the leaf of N. tabacum depends on a comprehensive coordination of Cd transport, including less cell wall binding, weaker impediment by the Casparian strip, and efficient xylem loading.
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Affiliation(s)
- Wu-Xing Huang
- College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan 450002, People's Republic of China
| | - Duo-Min Zhang
- College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan 450002, People's Republic of China
| | - Yu-Qiao Cao
- College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan 450002, People's Republic of China
| | - Bing-Jun Dang
- College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan 450002, People's Republic of China
| | - Wei Jia
- College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan 450002, People's Republic of China
| | - Zi-Cheng Xu
- College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan 450002, People's Republic of China
| | - Dan Han
- College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan 450002, People's Republic of China.
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11
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Bioinformatics and Transcriptional Study of the Nramp Gene in the Extreme Acidophile Acidithiobacillus ferrooxidans Strain DC. MINERALS 2020. [DOI: 10.3390/min10060544] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The family of Nramp (natural resistance-associated macrophage protein) metal ion transporter functions in diverse organisms from bacteria to humans. Acidithiobacillus ferrooxidans (At. ferrooxidans) is a Gram-negative bacterium that lives at pH 2 in high concentrations of soluble ferrous ion (600 mM). The AFE_2126 protein of At. ferrooxidans of the Dachang Copper Mine (DC) was analyzed by bioinformatics software or online tools, showing that it was highly homologous to the Nramp family, and its subcellular localization was predicted to locate in the cytoplasmic membrane. Transcriptional study revealed that AFE_2126 was expressed by Fe2+-limiting conditions in At. ferrooxidans DC. It can be concluded that the AFE_2126 protein may function in ferrous ion transport into the cells. Based on the ΔpH of the cytoplasmic membrane between the periplasm (pH 3.5) and the cytoplasm (pH 6.5), it can be concluded that Fe2+ is transported in the direction identical to that of the H+ gradient. This study indirectly confirmed that the function of Nramp in At. ferrooxidans DC can transport divalent iron ions.
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12
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Lu Z, Chen S, Han X, Zhang J, Qiao G, Jiang Y, Zhuo R, Qiu W. A Single Amino Acid Change in Nramp6 from Sedum Alfredii Hance Affects Cadmium Accumulation. Int J Mol Sci 2020; 21:E3169. [PMID: 32365876 PMCID: PMC7246828 DOI: 10.3390/ijms21093169] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 04/22/2020] [Accepted: 04/26/2020] [Indexed: 12/04/2022] Open
Abstract
SaNramp6 in Sedum alfredii encodes a membrane-localized metal transporter. We isolated the SaNramp6h allele from the hyperaccumulating ecotype (HE) of S. alfredii. When this allele was expressed in transgenic yeast and Arabidopsis thaliana, it enhanced their cadmium (Cd) sensitivity by increased Cd transport and accumulation. We isolated another allele, SaNramp6n, from a nonhyperaccumulating ecotype (NHE) of S. alfredii. Amino acid sequence comparisons revealed three amino acid differences between SaNramp6h and SaNramp6n. We investigated the Cd transport activity of the Nramp6 allele, and determined which residues are essential for the transport activity. We conducted structure-function analyses of SaNramp6 based on site-directed mutagenesis and functional assays of the mutants in yeast and Arabidopsis. The three residues that differed between SaNramp6h and SaNramp6n were mutated. Only the L157P mutation of SaNramp6h impaired Cd transport. The other mutations, S218N and T504A, did not affect the transport activity of SaNramp6h, indicating that these residues are not essential for metal selectivity. Transgenic plants overexpressing SaNramp6hL157P showed altered metal accumulation in shoots and roots. Our results suggest that the conserved site L157 is essential for the high metal transport activity of SaNramp6h. This information may be useful for limiting or increasing Cd transport by other plant natural resistance associated macrophage protein (NRAMP) proteins.
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Affiliation(s)
- Zhuchou Lu
- State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Xiangshan Road, Beijing 100091, China; (Z.L.); (S.C.); (X.H.); (G.Q.)
- The Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang, Hangzhou 311400, China
| | - Shuangshuang Chen
- State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Xiangshan Road, Beijing 100091, China; (Z.L.); (S.C.); (X.H.); (G.Q.)
- The Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang, Hangzhou 311400, China
- Institute of Leisure Agriculture, Jiangsu Academy of Agriculture Sciences, Nanjing 210014, China
| | - Xiaojiao Han
- State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Xiangshan Road, Beijing 100091, China; (Z.L.); (S.C.); (X.H.); (G.Q.)
- The Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang, Hangzhou 311400, China
| | - Jin Zhang
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA;
| | - Guirong Qiao
- State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Xiangshan Road, Beijing 100091, China; (Z.L.); (S.C.); (X.H.); (G.Q.)
- The Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang, Hangzhou 311400, China
| | - Yugen Jiang
- Agricultural Technology Extension Center of Fuyang District, Hangzhou 311400, China;
| | - Renying Zhuo
- State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Xiangshan Road, Beijing 100091, China; (Z.L.); (S.C.); (X.H.); (G.Q.)
- The Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang, Hangzhou 311400, China
| | - Wenmin Qiu
- State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Xiangshan Road, Beijing 100091, China; (Z.L.); (S.C.); (X.H.); (G.Q.)
- The Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang, Hangzhou 311400, China
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13
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Bozzi AT, McCabe AL, Barnett BC, Gaudet R. Transmembrane helix 6b links proton and metal release pathways and drives conformational change in an Nramp-family transition metal transporter. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49881-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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14
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Bozzi AT, McCabe AL, Barnett BC, Gaudet R. Transmembrane helix 6b links proton and metal release pathways and drives conformational change in an Nramp-family transition metal transporter. J Biol Chem 2019; 295:1212-1224. [PMID: 31882536 DOI: 10.1074/jbc.ra119.011336] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/10/2019] [Indexed: 12/15/2022] Open
Abstract
The natural resistance-associated macrophage protein (Nramp) family encompasses transition metal and proton cotransporters that are present in many organisms from bacteria to humans. Recent structures of Deinococcus radiodurans Nramp (DraNramp) in multiple conformations revealed the intramolecular rearrangements required for alternating access of the metal-binding site to the external or cytosolic environment. Here, using recombinant proteins and metal transport and cysteine accessibility assays, we demonstrate that two parallel cytoplasm-accessible networks of conserved hydrophilic residues in DraNramp, one lining the wide intracellular vestibule for metal release and the other forming a narrow proton transport pathway, are essential for metal transport. We further show that mutagenic or posttranslational modifications of transmembrane helix (TM) 6b, which structurally links these two pathways, impede normal conformational cycling and metal transport. TM6b contains two highly conserved histidines, His232 and His237 We found that different mutagenic perturbations of His232, just below the metal-binding site along the proton exit route, differentially affect DraNramp's conformational state, suggesting that His232 serves as a pivot point for conformational changes. In contrast, any replacement of His237, lining the metal exit route, locked the transporter in a transport-inactive outward-closed state. We conclude that these two histidines, and TM6b more broadly, help trigger the bulk rearrangement of DraNramp to the inward-open state upon metal binding and facilitate return of the empty transporter to an outward-open state upon metal release.
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Affiliation(s)
- Aaron T Bozzi
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Anne L McCabe
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Benjamin C Barnett
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
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15
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Shu H, Zhang J, Liu F, Bian C, Liang J, Liang J, Liang W, Lin Z, Shu W, Li J, Shi Q, Liao B. Comparative Transcriptomic Studies on a Cadmium Hyperaccumulator Viola baoshanensis and Its Non-Tolerant Counterpart V. inconspicua. Int J Mol Sci 2019; 20:E1906. [PMID: 30999673 PMCID: PMC6515270 DOI: 10.3390/ijms20081906] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/14/2019] [Accepted: 04/16/2019] [Indexed: 12/29/2022] Open
Abstract
Many Viola plants growing in mining areas exhibit high levels of cadmium (Cd) tolerance and accumulation, and thus are ideal organisms for comparative studies on molecular mechanisms of Cd hyperaccumulation. However, transcriptomic studies of hyperaccumulative plants in Violaceae are rare. Viola baoshanensis is an amazing Cd hyperaccumulator in metalliferous areas of China, whereas its relative V. inconspicua is a non-tolerant accumulator that resides at non-metalliferous sites. Here, comparative studies by transcriptome sequencing were performed to investigate the key pathways that are potentially responsible for the differential levels of Cd tolerance between these two Viola species. A cascade of genes involved in the ubiquitin proteosome system (UPS) pathway were observed to have constitutively higher transcription levels and more activation in response to Cd exposure in V. baoshanensis, implying that the enhanced degradation of misfolded proteins may lead to high resistance against Cd in this hyperaccumulator. Many genes related to sucrose metabolism, especially those involved in callose and trehalose biosynthesis, are among the most differentially expressed genes between the two Viola species, suggesting a crucial role of sucrose metabolism not only in cell wall modification through carbon supply but also in the antioxidant system as signaling molecules or antioxidants. A comparison among transcriptional patterns of some known transporters revealed that several tonoplast transporters are up-regulated in V. baoshanensis under Cd stress, suggesting more efficient compartmentalization of Cd in the vacuoles. Taken together, our findings provide valuable insight into Cd hypertolerance in V. baoshanensis, and the corresponding molecular mechanisms will be useful for future genetic engineering in phytoremediation.
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Affiliation(s)
- Haoyue Shu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Jun Zhang
- School of Biosciences and Biopharmaceutics, Guangdong Province Key Laboratory for Biotechnology Drug Candidates, Guangdong Pharmaceutical University, Guangzhou 510006, China.
| | - Fuye Liu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Chao Bian
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Jieliang Liang
- School of Life Sciences, South China Normal University, Guangzhou 510631, China.
| | - Jiaqi Liang
- School of Biosciences and Biopharmaceutics, Guangdong Province Key Laboratory for Biotechnology Drug Candidates, Guangdong Pharmaceutical University, Guangzhou 510006, China.
| | - Weihe Liang
- School of Biosciences and Biopharmaceutics, Guangdong Province Key Laboratory for Biotechnology Drug Candidates, Guangdong Pharmaceutical University, Guangzhou 510006, China.
| | - Zhiliang Lin
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Wensheng Shu
- School of Life Sciences, South China Normal University, Guangzhou 510631, China.
| | - Jintian Li
- School of Life Sciences, South China Normal University, Guangzhou 510631, China.
| | - Qiong Shi
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Bin Liao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
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