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Aspholm EE, Lidman J, Burmann BM. Structural basis of substrate recognition and allosteric activation of the proapoptotic mitochondrial HtrA2 protease. Nat Commun 2024; 15:4592. [PMID: 38816423 DOI: 10.1038/s41467-024-48997-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/14/2024] [Indexed: 06/01/2024] Open
Abstract
The mitochondrial serine protease HtrA2 is a human homolog of the Escherichia coli Deg-proteins exhibiting chaperone and proteolytic roles. HtrA2 is involved in both apoptotic regulation via its ability to degrade inhibitor-of-apoptosis proteins (IAPs), as well as in cellular maintenance as part of the cellular protein quality control machinery, by preventing the possible toxic accumulation of aggregated proteins. In this study, we use advanced solution NMR spectroscopy methods combined with biophysical characterization and biochemical assays to elucidate the crucial role of the substrate recognizing PDZ domain. This domain regulates the protease activity of HtrA2 by triggering an intricate allosteric network involving the regulatory loops of the protease domain. We further show that divalent metal ions can both positively and negatively modulate the activity of HtrA2, leading to a refined model of HtrA2 regulation within the apoptotic pathway.
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Affiliation(s)
- Emelie E Aspholm
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Göteborg, Sweden
| | - Jens Lidman
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Göteborg, Sweden
| | - Björn M Burmann
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden.
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Göteborg, Sweden.
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2
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Huang YM, Hsu TY, Liu CY, Hsieh YC, Lai KY, Yang YW, Lo KY. Exploring the multifaceted impact of lanthanides on physiological pathways in human breast cancer cells. Toxicology 2024; 502:153731. [PMID: 38253231 DOI: 10.1016/j.tox.2024.153731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/09/2024] [Accepted: 01/17/2024] [Indexed: 01/24/2024]
Abstract
Lanthanum (La) and cerium (Ce), rare earth elements with physical properties similar to calcium (Ca), are generally considered non-toxic when used appropriately. However, their ions possess anti-tumor capabilities. This investigation explores the potential applications and mechanisms of LaCl3 or CeCl3 treatment in triple-negative breast cancer (TNBC) cell lines. TNBC, characterized by the absence of estrogen receptor (ERα), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) expression, is prone to early metastasis and resistant to hormone therapy. Our results demonstrate that La/Ce treatment reduces cell growth, and when combined with cisplatin, it synergistically inhibits cell growth and the PI3K/AKT pathway. La and Ce induce oxidative stress by disrupting mitochondrial function, leading to protein oxidation. Additionally, they interfere with protein homeostasis and induce nucleolar stress. Furthermore, disturbance in F-actin web formation impairs cell migration. This study delves into the mechanism by which calcium-like elements La and Ce inhibit breast cancer cell growth, shedding light on their interference in mitochondrial function, protein homeostasis, and cytoskeleton assembly.
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Affiliation(s)
- Yi-Ming Huang
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, ROC
| | - Tsu-Yu Hsu
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, ROC
| | - Ching-Yu Liu
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, ROC
| | - Yu-Chen Hsieh
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, ROC
| | - Kuan-Yun Lai
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, ROC
| | - Ya-Wen Yang
- Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan, ROC.
| | - Kai-Yin Lo
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan, ROC.
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3
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Tao Y, Shen L, Feng C, Yang R, Qu J, Ju H, Zhang Y. Distribution of rare earth elements (REEs) and their roles in plant growth: A review. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 298:118540. [PMID: 34801619 DOI: 10.1016/j.envpol.2021.118540] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/28/2021] [Accepted: 11/15/2021] [Indexed: 06/13/2023]
Abstract
The increasing use of rare earth elements (REEs) in various industries has led to a rise in discharge points, thus increasing discharge rates, circulation, and human exposure. Therefore, REEs have received widespread attention as important emerging pollutants. This article thus summarizes and discusses the distribution and occurrence of REEs in the world's soil and water, and briefly introduces current REEs content analysis technology for the examination of different types of samples. Specifically, this review focuses on the impact of REEs on plants, including the distribution and fractionation of REEs in plants and their bioavailability, the effect of REEs on seed germination and growth, the role of REEs in plant resistance, the physiological and biochemical responses of plants in the presence of REEs, including mineral absorption and photosynthesis, as well as a description of the substitution mechanism of REEs competing for Ca in plant cells. Additionally, this article summarizes the potential mechanisms of REEs to activate endocytosis in plants and provides some insights into the mechanisms by which REEs affect endocytosis from a cell and molecular biology perspective. Finally, this article discusses future research prospects and summarizes current scientific findings that could serve as a basis for the development of more sustainable rare earth resource utilization strategies and the assessment of REEs in the environment.
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Affiliation(s)
- Yue Tao
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China
| | - Lu Shen
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China
| | - Chong Feng
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China
| | - Rongyi Yang
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China
| | - Jianhua Qu
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China
| | - Hanxun Ju
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China
| | - Ying Zhang
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, PR China.
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Yin H, Wang J, Zeng Y, Shen X, He Y, Ling L, Cao L, Fu X, Peng L, Chun C. Effect of the Rare Earth Element Lanthanum (La) on the Growth and Development of Citrus Rootstock Seedlings. PLANTS 2021; 10:plants10071388. [PMID: 34371591 PMCID: PMC8309403 DOI: 10.3390/plants10071388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 11/16/2022]
Abstract
Rare earth elements (REEs) can affect the growth and development of plants. However, few studies have been carried out on the effects of REEs on citrus seedlings. In this study, the growth parameters, toxicity symptoms, chlorophyll content, and La content of three citrus rootstocks are analyzed under different concentrations of La, a representative REE. The results show that the growth of citrus rootstock seedlings was stimulated at La ≤ 0.5 mmol·L−1 and inhibited at concentrations above 1 mmol·L−1. The chlorophyll and carotenoid contents of trifoliate orange (Poncirus trifoliata L. Raf.) and Ziyang Xiangcheng (C. junos Sieb. ex Tanaka) leaves of plants grown at low concentrations of La (≤1.5 mmol·L−1) were similar to those of the control but were significantly reduced at 4 mmol·L−1 La. Toxic symptoms gradually appeared with increasing La concentrations, with yellowed leaves and burst veins appearing at 4 mmol·L−1 La. The symptoms of toxicity were most severe in trifoliate orange, followed by Shatian Pomelo (Citrus grandis var. shatinyu Hort) and then Ziyang Xiangcheng. Moreover, in leaves, the Ca content was significantly negatively correlated with La content (p < 0.01). These results indicate that La has a hormesis effect on the growth of citrus rootstocks. Of the studied citrus seedlings, Ziyang Xiangcheng is the most resistant to La.
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Dong C, Jiao C, Xie C, Liu Y, Luo W, Fan S, Ma Y, He X, Lin A, Zhang Z. Effects of ceria nanoparticles and CeCl 3 on growth, physiological and biochemical parameters of corn (Zea mays) plants grown in soil. NANOIMPACT 2021; 22:100311. [PMID: 35559968 DOI: 10.1016/j.impact.2021.100311] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/01/2021] [Accepted: 03/13/2021] [Indexed: 06/15/2023]
Abstract
The release of toxic ions from metal-based nanoparticles (NPs) may play an important role in biological effects of NPs. In this life cycle study, physiological and biochemical responses of soil-grown corn (Zea mays) plants exposed to ceria NPs and its ionic counterparts Ce3+ ions at 0, 25, 75 and 225 mg Ce/kg were investigated. Both treatments tended to reduce the fresh weight and height of the plants at 28 days after sowing (DAS), and delay silk appearance and finally decrease fruit weight at harvest. Uptake and distribution of some mineral nutrients, Ca, P, Fe, B, Zn and Mn in the plants were disturbed. None of the treatments significantly affected activities of antioxidant enzymes and MDA contents in the roots and leaves at 28 DAS. At 90 DAS, ceria NPs and Ce3+ ions disturbed the homeostasis of antioxidative systems in the plants, Ce3+ ions at all concentrations provoked significant oxidative damage in the roots and significantly increased MDA levels as compare to the control. The results indicate that the effects of ceria NPs and Ce3+ ions on corn plants varied with different growth stages and ceria NPs had similar but less severe impacts than Ce3+ ions. Speciation analysis revealed there was mutual transformation between CeO2 and Ce3+ in the soil-plant system. It is speculated that Ce3+ ions play a key role in toxicity. To the authors' knowledge, this is the first report of a life cycle study on comparative toxicity of CeO2 NPs and Ce3+ ions on corn plants.
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Affiliation(s)
- Chaonan Dong
- College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Chunlei Jiao
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Changjian Xie
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yabo Liu
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Wenhe Luo
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shixian Fan
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yuhui Ma
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao He
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Aijun Lin
- College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Zhiyong Zhang
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing, 100049, China.
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Vorob'ev VN, Sibgatullin TA, Sterkhova KA, Alexandrov EA, Gogolev YV, Timofeeva OA, Gorshkov VY, Chevela VV. Ytterbium increases transmembrane water transport in Zea mays roots via aquaporin modulation. Biometals 2019; 32:901-908. [PMID: 31587124 DOI: 10.1007/s10534-019-00221-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 09/28/2019] [Indexed: 11/28/2022]
Abstract
In our study, the rare earth element ytterbium (Yb3+) was demonstrated to affect water exchange in roots of Zea mays seedlings. Herewith, the overall membrane permeability (Pd) increased. The Pd increase was determined by aquaporin activity but not the membrane lipid component since the closure of aquaporin channels due to low intracellular pH abolished the positive effect of Yb3+ on Pd. Additionally, the expression level of aquaporin genes ZmPIP2;2, ZmPIP2;6 and ZmTIP2;2 was increased when plants were grown in the presence of Yb3+. Our results indicate that previously described positive influence of rare earth metals on plant growth and productivity may be mediated (at least partially) by the modification of the plant hydraulic system.
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Affiliation(s)
- Vladimir N Vorob'ev
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of Russian Academy of Sciences, P.O. Box 30, Lobachevsky st., 2/13, Kazan, Russia, 420111. .,Kazan (Volga region) Federal University, Kremlyovskaya st., 18, 420008, Kazan, Russia.
| | - Timur A Sibgatullin
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of Russian Academy of Sciences, P.O. Box 30, Lobachevsky st., 2/13, Kazan, Russia, 420111
| | - Kseniya A Sterkhova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of Russian Academy of Sciences, P.O. Box 30, Lobachevsky st., 2/13, Kazan, Russia, 420111
| | - Evgeniy A Alexandrov
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of Russian Academy of Sciences, P.O. Box 30, Lobachevsky st., 2/13, Kazan, Russia, 420111
| | - Yuri V Gogolev
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of Russian Academy of Sciences, P.O. Box 30, Lobachevsky st., 2/13, Kazan, Russia, 420111.,Kazan (Volga region) Federal University, Kremlyovskaya st., 18, 420008, Kazan, Russia
| | - Olga A Timofeeva
- Kazan (Volga region) Federal University, Kremlyovskaya st., 18, 420008, Kazan, Russia
| | - Vladimir Y Gorshkov
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of Russian Academy of Sciences, P.O. Box 30, Lobachevsky st., 2/13, Kazan, Russia, 420111.,Kazan (Volga region) Federal University, Kremlyovskaya st., 18, 420008, Kazan, Russia
| | - Vladimir V Chevela
- Kazan (Volga region) Federal University, Kremlyovskaya st., 18, 420008, Kazan, Russia
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7
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Bio-mining of Lanthanides from Red Mud by Green Microalgae. Molecules 2019; 24:molecules24071356. [PMID: 30959876 PMCID: PMC6480188 DOI: 10.3390/molecules24071356] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 12/16/2022] Open
Abstract
Red mud is a by-product of alumina production containing lanthanides. Growth of green microalgae on red mud and the intracellular accumulation of lanthanides was tested. The best growing species was Desmodesmus quadricauda (2.71 cell number doublings/day), which accumulated lanthanides to the highest level (27.3 mg/kg/day), if compared with Chlamydomonas reinhardtii and Parachlorella kessleri (2.50, 2.37 cell number doublings and 24.5, 12.5 mg/kg per day, respectively). With increasing concentrations of red mud, the growth rate decreased (2.71, 2.62, 2.43 cell number doublings/day) due to increased shadowing of cells by undissolved red mud particles. The accumulated lanthanide content, however, increased in the most efficient alga Desmodesmus quadricauda within 2 days from zero in red-mud free culture to 12.4, 39.0, 54.5 mg/kg of dry mass at red mud concentrations of 0.03, 0.05 and 0.1%, respectively. Red mud alleviated the metal starvation caused by cultivation in incomplete nutrient medium without added microelements. Moreover, the proportion of lanthanides in algae grown in red mud were about 250, 138, 117% higher than in culture grown in complete nutrient medium at red mud concentrations of 0.03, 0.05, 0.1%. Thus, green algae are prospective vehicles for bio-mining or bio-leaching of lanthanides from red mud.
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8
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Vorob'ev VN, Mirziev SI, Alexandrov EA, Sibgatullin TA. Characteristics of water and ion exchange of Elodea nuttallii cells at high concentrations of lanthanides. CHEMOSPHERE 2016; 165:329-334. [PMID: 27664522 DOI: 10.1016/j.chemosphere.2016.09.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 09/09/2016] [Accepted: 09/12/2016] [Indexed: 06/06/2023]
Abstract
Changes of diffusive permeability of membranes of Elodea nuttallii cells following a short-term (60 min) treatment with high concentrations of lanthanides were recorded by the 1H NMR-diffusometry and conductometry methods. The 1-h infiltration of segments of Elodea nuttallii internodes in 10 mM solutions of nitrates of La, Nd and Lu resulted in the increased leakage of electrolytes from cells, but has no effect on a water diffusive permeability of membranes. In samples subjected to a 30 min pretreatment with a water channel inhibitor HgCl2 the water diffusive permeability of membranes (Pd) drops down under the influence of lanthanides, as well as an outcome of electrolytes. To explain the observed effects the change of spontaneous curvature of membrane lipid layer has been taken into consideration. The interaction of lanthanides with lipids of plasmalemma leads to the negative spontaneous curvature of lipid layer at which membrane channels are unclosed. Blocking of the ionic and water channels by mercury ions compensate the effect of change of spontaneous curvature of lipid layer.
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Affiliation(s)
- Vladimir N Vorob'ev
- Kazan Institute of Biochemistry and Biophysics, Kazan Science Center, Russian Academy of Sciences, P.O. Box 30, Lobachevsky st. 2/13, Kazan, 420111, Russia; Kazan (Volga) Federal University, Kremlevsky st. 16, Kazan, 420008, Russia
| | - Samat I Mirziev
- Kazan (Volga) Federal University, Kremlevsky st. 16, Kazan, 420008, Russia
| | | | - Timur A Sibgatullin
- Kazan Institute of Biochemistry and Biophysics, Kazan Science Center, Russian Academy of Sciences, P.O. Box 30, Lobachevsky st. 2/13, Kazan, 420111, Russia.
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Goecke F, Jerez CG, Zachleder V, Figueroa FL, Bišová K, Řezanka T, Vítová M. Use of lanthanides to alleviate the effects of metal ion-deficiency in Desmodesmus quadricauda (Sphaeropleales, Chlorophyta). Front Microbiol 2015; 6:2. [PMID: 25674079 PMCID: PMC4309186 DOI: 10.3389/fmicb.2015.00002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 01/02/2015] [Indexed: 11/13/2022] Open
Abstract
Lanthanides are biologically non-essential elements with wide applications in technology and industry. Their concentration as environmental contaminants is, therefore, increasing. Although non-essential, lanthanides have been proposed (and even used) to produce beneficial effects in plants, even though their mechanisms of action are unclear. Recently, it was suggested that they may replace essential elements. We tested the effect of low concentrations of lanthanides on the common freshwater microalga Desmodesmus quadricauda, grown under conditions of metal ion-deficiency (lower calcium or manganese concentrations). Our goal was to test if lanthanides can replace essential metals in their functions. Physiological stress was recorded by studying growth and photosynthetic activity using a pulse amplitude modulation (PAM) fluorimeter. We found that nutrient stress reduced parameters of growth and photosynthesis, such as maximal quantum yield, relative electron transport rate, photon capturing efficiency and light saturation irradiance. After adding low concentrations of five lanthanides, we confirmed that they can produce a stimulatory effect on microalgae, depending on the nutrient (metal) deprivation. In the case of a calcium deficit, the addition of lanthanides partly alleviated the adverse effects, probably by a partial substitution of the element. In contrast, with manganese deprivation (and at even lower concentrations), lanthanides enhanced the deleterious effect on cellular growth and photosynthetic competence. These results show that lanthanides can replace essential elements, but their effects on microalgae depend on stress and the nutritional state of the microalgae, raising the possibility of environmental impacts at even low concentrations.
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Affiliation(s)
- Franz Goecke
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology Academy of Sciences of the Czech Republic Třeboň, Czech Republic
| | - Celia G Jerez
- Department of Ecology, Faculty of Sciences, University of Málaga Málaga, Spain
| | - Vilém Zachleder
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology Academy of Sciences of the Czech Republic Třeboň, Czech Republic
| | - Félix L Figueroa
- Department of Ecology, Faculty of Sciences, University of Málaga Málaga, Spain
| | - Kateřina Bišová
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology Academy of Sciences of the Czech Republic Třeboň, Czech Republic
| | - Tomáš Řezanka
- Department of Microbiology, Institute of Microbiology Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Milada Vítová
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology Academy of Sciences of the Czech Republic Třeboň, Czech Republic
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Wang CR, Wang QY, Tian Y, Zhang JF, Li ZX, Cao P, Zhu M, Li TT. Lanthanum ions intervened in enzymatic production and elimination of reactive oxygen species in leaves of rice seedlings under cadmium stress. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:1656-1664. [PMID: 24753051 DOI: 10.1002/etc.2610] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 03/28/2014] [Accepted: 04/13/2014] [Indexed: 06/03/2023]
Abstract
Rare earth elements at proper concentrations were observed to alleviate heavy metal stress. However, the potential mechanisms of alleviation are not clear. Thus, the present study focused on the mechanisms of lanthanum (La) ions on the generation and elimination of reactive oxygen species (ROS) production in leaves of rice seedlings hydroponically cultivated in 30 µM cadmium chloride (CdCl2) for 2 d. Results showed that the decline of superoxide (O2 · (-)) or hydrogen peroxide (H2O2) was attributed not only to the decreased expressions of nicotinamide adenine dinucleotide phosphate oxidases-related gene, protein synthesis, and isozymes, but also to the decrease of xanthine oxidase, diamine oxidase, and guaiacol peroxidases isozymes and activities. Genes and isozymes related to superoxide dismutase, catalase, and ascorbate peroxidase were also differentially upregulated to control ROS accumulation when proper concentrations of La were combined with 30 µM Cd. Based on the results, one may conclude that La at proper concentrations not only limited the generation of O2 · (-) and H2O2 from the enzymatic sources but also promoted the elimination of O2 · (-) and H2O2 via the upregulating expressions of antioxidant enzyme-related genes and activities in the rice seedling's leaves under Cd stress.
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Affiliation(s)
- Cheng-Run Wang
- School of Life Science, Huainan Normal University, Huainan, People's Republic of China
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Turra C, Fernandes EADN, Bacchi MA, Barbosa Júnior F, Sarriés GA, Blumer L. Chemical elements in organic and conventional sweet oranges. Biol Trace Elem Res 2011; 144:1289-94. [PMID: 21735113 DOI: 10.1007/s12011-011-9127-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 06/15/2011] [Indexed: 10/18/2022]
Abstract
This work focuses on the determination of chemical elements in sweet oranges of variety Valencia produced under organic and conventional systems using instrumental neutron activation analysis and inductively coupled plasma mass spectrometry. The distribution of chemical elements was variable among the fruit parts with usually higher concentrations of Br, Ca, Ce, K, La, Na, Rb, and Sc in the peel. However, K, Na, and Rb also presented high values in the juice samples, while Fe and Zn were higher in the seeds. Differences between organic and conventional oranges were found for Br and Cu.
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Affiliation(s)
- Christian Turra
- Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Caixa Postal 96, 13400-970, Piracicaba, Brazil.
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12
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Milograna SR, Bell FT, McNamara JC. Signal transduction, plasma membrane calcium movements, and pigment translocation in freshwater shrimp chromatophores. ACTA ACUST UNITED AC 2011; 313:605-17. [PMID: 20683865 DOI: 10.1002/jez.633] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Crustacean color change results from the differential translocation of chromatophore pigments, regulated by neurosecretory peptides like red pigment concentrating hormone (RPCH) that, in the red ovarian chromatophores of the freshwater shrimp Macrobrachium olfersi, triggers pigment aggregation via increased cytosolic cGMP and Ca(2+) of both smooth endoplasmatic reticulum (SER) and extracellular origin. However, Ca(2+) movements during RPCH signaling and the mechanisms that regulate intracellular [Ca(2+)] are enigmatic. We investigate Ca(2+) transporters in the chromatophore plasma membrane and Ca(2+) movements that occur during RPCH signal transduction. Inhibition of the plasma membrane Ca(2+)-ATPase by La(3+) and indirect inhibition of the Na(+)/Ca(2+) exchanger by ouabain induce pigment aggregation, revealing a role for both in Ca(2+) extrusion. Ca(2+) channel blockade by La(3+) or Cd(2+) strongly inhibits slow-phase RPCH-triggered aggregation during which pigments disperse spontaneously. L-type Ca(2+) channel blockade by gabapentin markedly reduces rapid-phase translocation velocity; N- or P/Q-type blockade by ω-conotoxin MVIIC strongly inhibits RPCH-triggered aggregation and reduces velocity, effects revealing RPCH-signaled influx of extracellular Ca(2+). Plasma membrane depolarization, induced by increasing external K(+) from 5 to 50 mM, produces Ca(2+)-dependent pigment aggregation, whereas removal of K(+) from the perfusate causes pigment hyperdispersion, disclosing a clear correlation between membrane depolarization and pigment aggregation; K(+) channel blockade by Ba(2+) also partially inhibits RPCH action. We suggest that, during RPCH signal transduction, Ca(2+) released from the SER, together with K(+) channel closure, causes chromatophore membrane depolarization, leading to the opening of predominantly N- and/or P/Q-type voltage-gated Ca(2+) channels, and a Ca(2+)/cGMP cascade, resulting in pigment aggregation.
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Affiliation(s)
- Sarah Ribeiro Milograna
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
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14
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Structural identification of cation binding pockets in the plasma membrane proton pump. Proc Natl Acad Sci U S A 2010; 107:21400-5. [PMID: 21098259 DOI: 10.1073/pnas.1010416107] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The activity of P-type plasma membrane H(+)-ATPases is modulated by H(+) and cations, with K(+) and Ca(2+) being of physiological relevance. Using X-ray crystallography, we have located the binding site for Rb(+) as a K(+) congener, and for Tb(3+) and Ho(3+) as Ca(2+) congeners. Rb(+) is found coordinated by a conserved aspartate residue in the phosphorylation domain. A single Tb(3+) ion is identified positioned in the nucleotide-binding domain in close vicinity to the bound nucleotide. Ho(3+) ions are coordinated at two distinct sites within the H(+)-ATPase: One site is at the interface of the nucleotide-binding and phosphorylation domains, and the other is in the transmembrane domain toward the extracellular side. The identified binding sites are suggested to represent binding pockets for regulatory cations and a H(+) binding site for protons leaving the pump molecule. This implicates Ho(3+) as a novel chemical tool for identification of proton binding sites.
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15
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Chrysomallidou KE, Perlepes SP, Terzis A, Raptopoulou CP. Synthesis, crystal structures and spectroscopic studies of praseodymium(III) malonate complexes. Polyhedron 2010. [DOI: 10.1016/j.poly.2010.08.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Guo S, Cao R, Lu A, Zhou Q, Lu T, Ding X, Li C, Huang X. One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III). J Biol Inorg Chem 2008; 13:587-97. [PMID: 18274791 DOI: 10.1007/s00775-008-0347-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2007] [Accepted: 01/27/2008] [Indexed: 11/25/2022]
Abstract
One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III) was investigated using some biophysical and biochemical methods. Firstly, it was found that a large amount of Tb(III) can be distributed on the cell wall, that some Tb(III) can enter into the horseradish cell, indicating that peroxidase was mainly distributed on cell wall, and thus that Tb(III) would interact with horseradish peroxidase (HRP) in the plant. In addition, peroxidase bioactivity was decreased in the presence of Tb(III). Secondly, a new peroxidase-containing Tb(III) complex (Tb-HRP) was obtained from horseradish after treatment with Tb(III); the molecular mass of Tb-HRP is near 44 kDa and the pI is about 8.80. Thirdly, the electrocatalytic activity of Tb-HRP is much lower than that of HRP obtained from horseradish without treatment with Tb(III). The decrease in the activity of Tb-HRP is due to the destruction (unfolding) of the conformation in Tb-HRP. The planarity of the heme active center in the Tb-HRP molecule was increased and the extent of exposure of Fe(III) in heme was decreased, leading to inhibition of the electron transfer. The microstructure change in Tb-HRP might be the result of the inhibition effect of Tb(III) on peroxidase activity in horseradish.
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Affiliation(s)
- Shaofen Guo
- Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing 210097, People's Republic of China
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17
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Wang L, Huang X, Zhou Q. Effects of rare earth elements on the distribution of mineral elements and heavy metals in horseradish. CHEMOSPHERE 2008; 73:314-319. [PMID: 18639916 DOI: 10.1016/j.chemosphere.2008.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 05/26/2008] [Accepted: 06/02/2008] [Indexed: 05/26/2023]
Abstract
In order to investigate the effects of rare earth elements (REEs) on horseradish, the distribution of the mineral elements and heavy metals in different organs of horseradish have been studied by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Meanwhile, three variable major parameters, namely the concentration of REEs, the type of REEs, and the growth stage of plant were chosen. The results indicated that the test REEs, Ce(III) and Tb(III), could be accumulated in leaves, stems and roots of horseradish. In addition, we found that the content of mineral elements was increased in horseradish treated with 20mgl(-1) of Ce(III), but not those with the 20mgl(-1) of Tb(III). Moreover, the content of mineral elements in horseradish was decreased with the increasing concentration of REEs (100, 300mgl(-1)). Furthermore, we found that there were the opposite effects on the content of the heavy metals in horseradish treated with REEs. Finally, we found that the effect of REEs on the accumulation of REEs, and the content of mineral elements or heavy metals of horseradish during vigorous growth stage, no matter positive or negative, was more obvious than that of the other growth stages. These results demonstrated that the distribution behaviors of mineral elements and heavy metals in horseradish can be affected by the type and concentration of REEs, and the growth period of plant.
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Affiliation(s)
- Lihong Wang
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China
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18
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Inesi G, Lewis D, Nikic D, Hussain A, Kirtley ME. Long-range intramolecular linked functions in the calcium transport ATPase. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 65:185-215. [PMID: 1533299 DOI: 10.1002/9780470123119.ch5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- G Inesi
- Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore, Maryland
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19
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Moreira OC, Rios PF, Barrabin H. Inhibition of plasma membrane Ca(2+)-ATPase by CrATP. LaATP but not CrATP stabilizes the Ca(2+)-occluded state. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1708:411-9. [PMID: 15975546 DOI: 10.1016/j.bbabio.2005.05.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 05/16/2005] [Accepted: 05/24/2005] [Indexed: 11/20/2022]
Abstract
The bidentate complex of ATP with Cr(3+), CrATP, is a nucleotide analog that is known to inhibit the sarcoplasmic reticulum Ca(2+)-ATPase and the Na(+),K(+)-ATPase, so that these enzymes accumulate in a conformation with the transported ion (Ca(2+) and Na(+), respectively) occluded from the medium. Here, it is shown that CrATP is also an effective and irreversible inhibitor of the plasma membrane Ca(2+)-ATPase. The complex inhibited with similar efficiency the Ca(2+)-dependent ATPase and the phosphatase activities as well as the enzyme phosphorylation by ATP. The inhibition proceeded slowly (T(1/2)=30 min at 37 degrees C) with a K(i)=28+/-9 microM. The inclusion of ATP, ADP or AMPPNP in the inhibition medium effectively protected the enzyme against the inhibition, whereas ITP, which is not a PMCA substrate, did not. The rate of inhibition was strongly dependent on the presence of Mg(2+) but unaltered when Ca(2+) was replaced by EGTA. In spite of the similarities with the inhibition of other P-ATPases, no apparent Ca(2+) occlusion was detected concurrent with the inhibition by CrATP. In contrast, inhibition by the complex of La(3+) with ATP, LaATP, induced the accumulation of phosphoenzyme with a simultaneous occlusion of Ca(2+) at a ratio close to 1.5 mol/mol of phosphoenzyme. The results suggest that the transport of Ca(2+) promoted by the plasma membrane Ca(2+)-ATPase goes through an enzymatic phospho-intermediate that maintains Ca(2+) ions occluded from the media. This intermediate is stabilized by LaATP but not by CrATP.
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Affiliation(s)
- Otacilio C Moreira
- Instituto de Bioquímica Médica, Programa de Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, CEP 21941-590, Rio de Janeiro, Brazil
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20
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Birkenbeil H, Dedos SG. Ca(2+) as second messenger in PTTH-stimulated prothoracic glands of the silkworm, Bombyx mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2002; 32:1625-1634. [PMID: 12429114 DOI: 10.1016/s0965-1748(02)00101-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Measurements of Ca(2+) influx and [Ca(2+)](i) changes in Fura-2/AM-loaded prothoracic glands (PGs) of the silkworm, Bombyx mori, were used to identify Ca(2+) as the actual second messenger of the prothoracicotropic hormone (PTTH) of this insect. Dose-dependent increases of [Ca(2+)](i) in PG cells were recorded in the presence of recombinant PTTH (rPTTH) within 5 minutes. The rPTTH-mediated increases of [Ca(2+)](i) levels were dependent on extracellular Ca(2+). They were not blocked by the dihydropyridine derivative, nitrendipine, an antagonist of high-voltage-activated (HVA) Ca(2+) channels, and by bepridil, an antagonist of low-voltage-activated (LVA) Ca(2+) channels. The trivalent cation La(3+), a non-specific blocker of plasma membrane Ca(2+) channels, eliminated the rPTTH-stimulated increase of [Ca(2+)](i) levels in PG cells and so did amiloride, an inhibitor of T-type Ca(2+) channels. Incubation of PG cells with thapsigargin resulted in an increase of [Ca(2+)](i) levels, which was also dependent on extracellular Ca(2+) and was quenched by amiloride, suggesting the existence of store-operated plasma membrane Ca(2+) channels, which can also be inhibited by amiloride. Thapsigargin and rPTTH did not operate independently in stimulating increases of [Ca(2+)](i) levels and one agent's mediated increase of [Ca(2+)](i) was eliminated in the presence of the other. TMB-8, an inhibitor of intracellular Ca(2+) release from inositol 1,4,5 trisphosphate (IP(3))-sensitive Ca(2+) stores, blocked the rPTTH-stimulated increases of [Ca(2+)](i) levels, suggesting an involvement of IP(3) in the initiation of the rPTTH signaling cascade, whereas ryanodine did not influence the rPTTH-stimulated increases of [Ca(2+)](i) levels. The combined results indicate the presence of a cross-talk mechanism between the [Ca(2+)](i) levels, filling state of IP(3)-sensitive intracellular Ca(2+) stores and the PTTH-receptor's-mediated Ca(2+) influx.
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Affiliation(s)
- Heiner Birkenbeil
- Sächsische Akademie der Wissenschaften zu Leipzig AG Neurohormonale Wirkungsmechanismen, Erbert-Str. 1, PF 100322, 07703, Jena, Germany.
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21
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Wu ML, Chen JH, Chen WH, Chen YJ, Chu KC. Novel role of the Ca(2+)-ATPase in NMDA-induced intracellular acidification. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:C717-27. [PMID: 10516102 DOI: 10.1152/ajpcell.1999.277.4.c717] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanism involved in N-methyl-D-glucamine (NMDA)-induced Ca(2+)-dependent intracellular acidosis is not clear. In this study, we investigated in detail several possible mechanisms using cultured rat cerebellar granule cells and microfluorometry [fura 2-AM or 2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein-AM]. When 100 microM NMDA or 40 mM KCl was added, a marked increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)) and a decrease in the intracellular pH were seen. Acidosis was completely prevented by the use of Ca(2+)-free medium or 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid-AM, suggesting that it resulted from an influx of extracellular Ca(2+). The following four mechanisms that could conceivably have been involved were excluded: 1) Ca(2+) displacement of intracellular H(+) from common binding sites; 2) activation of an acid loader or inhibition of acid extruders; 3) overproduction of CO(2) or lactate; and 4) collapse of the mitochondrial membrane potential due to Ca(2+) uptake, resulting in inhibition of cytosolic H(+) uptake. However, NMDA/KCl-induced acidosis was largely prevented by glycolytic inhibitors (iodoacetate or deoxyglucose in glucose-free medium) or by inhibitors of the Ca(2+)-ATPase (i.e., Ca(2+)/H(+) exchanger), including La(3+), orthovanadate, eosin B, or an extracellular pH of 8.5. Our results therefore suggest that Ca(2+)-ATPase is involved in NMDA-induced intracellular acidosis in granule cells. We also provide new evidence that NMDA-evoked intracellular acidosis probably serves as a negative feedback signal, probably with the acidification itself inhibiting the NMDA-induced [Ca(2+)](i) increase.
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Affiliation(s)
- M L Wu
- Department of Physiology, College of Medicine, National Taiwan University Hospital, Taipei, Taiwan.
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22
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Hunter GW, Bigelow DJ, Squier TC. Lysophosphatidylcholine modulates catalytically important motions of the Ca-ATPase phosphorylation domain. Biochemistry 1999; 38:4604-12. [PMID: 10194382 DOI: 10.1021/bi982392g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Catalytically important motions of the Ca-ATPase, modulated by the physical properties of surrounding membrane phospholipids, have been suggested to be rate-limiting under physiological conditions. To identify the nature of the structural coupling between the Ca-ATPase and membrane phospholipids, we have investigated the functional and structural effects resulting from the incorporation of the lysophospholipid 1-myristoyl-2-hydroxy-sn-glycerol-3-phosphocholine (LPC) into native sarcoplasmic reticulum (SR) membranes. Nonsolubilizing concentrations of LPC abolish changes in fluorescence signals associated with either intrinsic or extrinsic chromophores that monitor normal conformational transitions accompanying calcium activation of the Ca-ATPase. There are corresponding decreases in the rates of calcium transport coupled to ATP hydrolysis, suggesting that LPC may increase conformational barriers associated with catalytic function. Fluorescence anisotropy measurements of the lipid analogue 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) partitioned into SR membranes indicate that LPC does not significantly modify lipid acyl chain rotational dynamics, suggesting differences in headgroup conformation between LPC and diacylglycerol phosphatidylcholines. Complementary measurements using phosphorescence anisotropy of erythrosin isothiocyanate at Lys464 on the Ca-ATPase provide a measure of the dynamic structure of the phosphorylation domain, and indicate that LPC restricts the amplitude of rotational motion. These results suggest a structural linkage between the cytosolic phosphorylation domain and the conformation of membrane phospholipid headgroups. Thus, changes in membrane phospholipid composition can modulate membrane surface properties and affect catalytically important motions of the Ca-ATPase in a manner that suggests a role for LPC generated during signal transduction.
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Affiliation(s)
- G W Hunter
- Biochemistry and Biophysics Section, Department of Molecular Biosciences, University of Kansas, Lawrence 66045-2106, USA
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23
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Hunter GW, Negash S, Squier TC. Phosphatidylethanolamine modulates Ca-ATPase function and dynamics. Biochemistry 1999; 38:1356-64. [PMID: 9930998 DOI: 10.1021/bi9822224] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phospholipids containing phosphoethanolamine (PE) headgroups within biological membranes have been suggested to be important with respect to the functional regulation of membrane proteins, including the Ca-ATPase in sarcoplasmic reticulum (SR). To investigate the role of PE headgroups in modulating the catalytic activity of the Ca-ATPase, we have reconstituted the Ca-ATPase into unilamellar liposomes containing defined amounts of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC). The enzymatic activity of the Ca-ATPase progressively increases upon incorporation of increasing amounts of PE into reconstituted vesicles, and approaches that characteristic of native SR membranes. To identify structural changes that correlate with enzyme activation, we have used frequency-domain phosphorescence spectroscopy to measure the rotational dynamics of erythrosin isothiocyanate covalently bound to Lys464 in the phosphorylation domain of the Ca-ATPase. Progressive increases in the rotational dynamics of the phosphorylation domain result from the incorporation of increasing amounts of DOPE, and correlate with enhanced enzymatic function. These results suggest that PE headgroups induce dynamic structural rearrangements involving the phosphorylation domain that modify the rates of nucleotide utilization. In contrast, no changes in the rotational dynamics of the lipid acyl chains are observed irrespective of the PE content. Therefore, the enhanced ATP hydrolytic activity associated with the incorporation of DOPE into these proteoliposomes is the result of specific noncovalent interactions involving PE phospholipid headgroups and the Ca-ATPase.
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Affiliation(s)
- G W Hunter
- Biochemistry and Biophysics Section, Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045-2106, USA
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24
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Huang S, Squier TC. Enhanced rotational dynamics of the phosphorylation domain of the Ca-ATPase upon calcium activation. Biochemistry 1998; 37:18064-73. [PMID: 9922175 DOI: 10.1021/bi981997+] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have used labeling conditions that permit the specific and covalent attachment of erythrosin isothiocyanate (Er-ITC) to Lys464 within the phosphorylation domain of the Ca-ATPase in skeletal sarcoplasmic reticulum membranes. These labeling conditions do not interfere with high-affinity ATP binding, phosphoenzyme formation, or phosphoenzyme hydrolysis [Huang, S., Negash, S., and Squier, T. C. (1998) Biochemistry 37, 6949-6957]. Thus, we can use frequency-domain phosphorescence spectroscopy to measure the rotational dynamics of the Ca-ATPase stabilized in different enzymatic states corresponding to the absence of bound ligands (E), calcium activation (E x Ca2), the presence of bound nucleotide (E x ATP), and formation of phosphoenzyme (E-P). We resolve three rotational correlation times corresponding to (i) a large-amplitude domain motion of the phosphorylation domain (phi1 approximately 5 +/- 1 micros), (ii) overall protein rotational motion with respect to the membrane normal (phi2 approximately 50 +/- 10 micros), and (iii) the rotational motion of the SR vesicles (phi3 approximately 1.1 +/- 0.4 ms). No differences are observed in the rotational dynamics of E, E x ATP, or E-P, indicating that phosphoenzyme formation or nucleotide binding result in no global structural changes involving the phosphorylation domain. In contrast, calcium activation enhances the amplitude of motion of the phosphorylation domain. These observed calcium-dependent changes in rotational dynamics result from structural changes within a single Ca-ATPase polypeptide chain, since protein-protein interactions do not change upon calcium binding. Thus, calcium binding induces concerted domain motions within a single Ca-ATPase polypeptide chain that may play a critical role in facilitating substrate binding and utilization.
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Affiliation(s)
- S Huang
- Department of Molecular Biosciences, University of Kansas, Lawrence 66045-2106, USA
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25
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Soler F, Plenge-Tellechea F, Fortea I, Fernandez-Belda F. Cyclopiazonic acid effect on Ca2+-dependent conformational states of the sarcoplasmic reticulum ATPase. Implication for the enzyme turnover. Biochemistry 1998; 37:4266-74. [PMID: 9521749 DOI: 10.1021/bi971455c] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The affinity of sarcoplasmic reticulum Ca2+-ATPase for cyclopiazonic acid is dependent on the conformational state of the enzyme. It is high in the absence of Ca2+ but low in its presence. When Ca2+ was added to the enzyme in the presence of equimolar toxin, the apparent rate constant for Ca2+ binding was 0.6 min-1 when measured at 37 degrees C. The apparent equilibrium constant for Ca2+ dissociation increased from 0.2 to 0.6 microM at neutral pH, and from 5.9 to 37 microM at pH 6.0. The apparent equilibrium constant for Ca2+ dissociation increased progressively as the amount of toxin increased above an equimolar level. Cyclopiazonic acid decreased phosphorylation by ATP and Ca2+ when the enzyme in the absence of Ca2+ was incubated in the presence of toxin, although no effect was observed after a preliminary incubation with Ca2+ at 37 degrees C. Cyclopiazonic acid incubated with the enzyme in the presence of Ca2+ could be eliminated with a Sephadex column. However, the toxin could not be removed when it was incubated with the enzyme in the absence of Ca2+. In the latter case, cyclopiazonic acid was eliminated when the enzyme in the presence of toxin was incubated with Ca2+ at 37 degrees C. Under turnover conditions and in the presence of 10 microM ATP, the toxin-enzyme interaction can be characterized by an apparent Kd of 7 nM. With an ATP concentration of 1 mM, the enzyme was inhibited completely at a toxin/enzyme molar ratio of approximately 10. Furthermore, enzyme activity was observed to recover at a toxin/enzyme molar ratio of 1 when the Ca2+ concentration was raised, which is consistent with the competitive character of cyclopiazonic acid and Ca2+. It is concluded that ATP and Ca2+ can protect against cyclopiazonic acid inhibition.
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Affiliation(s)
- F Soler
- Departamento de Bioquimica y Biologia Molecular A, Edificio de Veterinaria, Universidad de Murcia, Spain
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26
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Liang F, Cunningham KW, Harper JF, Sze H. ECA1 complements yeast mutants defective in Ca2+ pumps and encodes an endoplasmic reticulum-type Ca2+-ATPase in Arabidopsis thaliana. Proc Natl Acad Sci U S A 1997; 94:8579-84. [PMID: 9238019 PMCID: PMC23025 DOI: 10.1073/pnas.94.16.8579] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/1997] [Accepted: 05/27/1997] [Indexed: 02/04/2023] Open
Abstract
To understand the structure, role, and regulation of individual Ca2+ pumps in plants, we have used yeast as a heterologous expression system to test the function of a gene from Arabidopsis thaliana (ECA1). ECA1 encoded a 116-kDa polypeptide that has all the conserved domains common to P-type Ca2+ pumps (EC 3.6.1.38). The amino acid sequence shared more identity with sarcoplasmic/endoplasmic reticulum (53%) than with plasma membrane (32%) Ca2+ pumps. Yeast mutants defective in a Golgi Ca2+ pump (pmr1) or both Golgi and vacuolar Ca2+ pumps (pmr1 pmc1 cnb1) were sensitive to growth on medium containing 10 mM EGTA or 3 mM Mn2+. Expression of ECA1 restored growth of either mutant on EGTA. Membranes were isolated from the pmr1 pmc1 cnb1 mutant transformed with ECA1 to determine if the ECA1 polypeptide (ECA1p) could be phosphorylated as intermediates of the reaction cycle of Ca2+-pumping ATPases. In the presence of [gamma-32P]ATP, ECA1p formed a Ca2+-dependent [32P]phosphoprotein of 106 kDa that was sensitive to hydroxylamine. Cyclopiazonic acid, a blocker of animal sarcoplasmic/endoplasmic reticulum Ca2+ pumps, inhibited the formation of the phosphoprotein, whereas thapsigargin did not. Immunoblotting with an antibody against the carboxyl tail showed that ECA1p was associated mainly with the endoplasmic reticulum membranes isolated from Arabidopsis plants. The results support the model that ECA1 encodes an endoplasmic reticulum-type Ca2+ pump in Arabidopsis. The ability of ECA1p to restore growth of mutant pmr1 on medium containing Mn2+, and the formation of a Mn2+-dependent phosphoprotein suggested that ECA1p may also regulate Mn2+ homeostasis by pumping Mn2+ into endomembrane compartments of plants.
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Affiliation(s)
- F Liang
- Department of Plant Biology, University of Maryland, College Park, MD 20742, USA
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27
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A direct carbon-13 and nitrogen-15 NMR study of samarium(III) complexation with nitrate and isothiocyanate in aqueous solvent mixtures. J SOLUTION CHEM 1994. [DOI: 10.1007/bf00974101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Conformation of Ca(2+)-ATPase in two crystal forms. Effects of Ca2+, thapsigargin, adenosine 5'-(beta, gamma-methylene)triphosphate), and chromium(III)-ATP on crystallization. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)78168-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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29
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Wawrzynów A, Collins JH. Chemical modification of the Ca(2+)-ATPase of rabbit skeletal muscle sarcoplasmic reticulum: identification of sites labeled with aryl isothiocyanates and thiol-directed conformational probes. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1203:60-70. [PMID: 8218393 DOI: 10.1016/0167-4838(93)90036-q] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The Ca(2+)-ATPase protein of rabbit skeletal muscle sarcoplasmic reticulum is a single polypeptide chain of 1001 amino-acid residues. Among these residues are 24 Cys, 9 of which have previously been shown to be accessible to one or more thiol-specific reagents. Many studies on the structure and function of this Ca(2+)-ATPase have made use of sulfhydryl-directed, conformationally-sensitive probes, but the labeling sites for these probes have been directly identified in only a few cases, causing uncertainty in the interpretation of results. In the present work, we have investigated the Ca(2+)-ATPase labeling sites for three thiol-directed spectroscopic probes: fluorescein 5'-maleimide (Fmal), 4-dimethylaminophenyl-azo phenyl-4'-maleimide (DABmal), and 4-dimethylaminophenylazophenyl-4'-iodoacetamide (DABIA). Labeled Ca(2+)-ATPase was digested exhaustively with trypsin, and labeled peptides were purified and sequenced in order to identify the labeled Cys residues. Our results do not support the widely held assumptions that Cys-344 and Cys-364 are the most reactive residues with maleimide-based reagents, while Cys-670 and Cys-674 react most rapidly with iodoacetamide derivatives. We found instead that Fmal reacted most rapidly with Cys-471, followed by Cys-364, and more slowly with Cys-498, -525, -614 and -636. DABmal reacted most rapidly with Cys-364, followed by Cys-614, and more slowly with Cys-471, -498, -636 and -670. Cys-344 was not labeled by either Fmal or DABmal. DABIA reacted with the same six Cys residues, including Cys-670, as were labeled with DABmal, but in much lower yield. There was no evidence for labeling of Cys-674 with DABIA. The high reactivity of Fmal, but not the more hydrophobic DABmal, with Cys-471 is of interest because of previous studies suggesting that the accessibility of Cys-471 is influenced by ATP and that fluorescein derivatives bind to a hydrophobic pocket in the ATP binding site. Another derivative, fluorescein-5'-isothiocyanate (FITC), is thought to label the catalytic site of the Ca(2+)-ATPase and has been widely used as a conformational probe in structure-function studies on this and related proteins. We reinvestigated the chemical modification of the Ca(2+)-ATPase by FITC and 4-dimethyl-aminophenyl-4'-isothiocyanate (DABITC). Incorporation of stoichiometric amounts of FITC resulted in a nearly complete loss of ATPase activity. Labeling and inactivation of the Ca(2+)-ATPase by FITC did not occur in the presence of ATP. DABITC was less reactive than FITC, and did not inactivate the Ca(2+)-ATPase to any significant extent.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- A Wawrzynów
- Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore 21201
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30
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Sumbilla C, Lu L, Lewis D, Inesi G, Ishii T, Takeyasu K, Feng Y, Fambrough D. Ca(2+)-dependent and thapsigargin-inhibited phosphorylation of Na+,K(+)-ATPase catalytic domain following chimeric recombination with Ca(2+)-ATPase. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)36908-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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31
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Andersen JP, Vilsen B. Functional consequences of substitution of the seven-residue segment LysIleArgAspGlnMetAla240 located in the stalk helix S3 of the Ca(2+)-ATPase of sarcoplasmic reticulum. Biochemistry 1993; 32:10015-20. [PMID: 8399128 DOI: 10.1021/bi00089a017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Site-directed mutagenesis was used to substitute the seven-residue segment LysIleArgAspGlnMetAla240 located at the NH2- terminal end of the "stalk" helix S3, near the beta-strand domain, in the sarcoplasmic reticulum Ca(2+)-ATPase of rabbit fast twitch muscle, with the corresponding Na+,K(+)-ATPase segment ArgIleAlaThrLeuAlaSer. This led to a new phenotypic variant of Ca(2+)-ATPase. The overall turnover rates for Ca2+ transport and ATP hydrolysis measured at 27 and 37 degrees C, respectively, were reduced to 30-40% of the wild-type rates. Analysis of the phosphoenzyme intermediates at 0 degrees C showed that the ADP-insensitive phosphoenzyme intermediate accumulated under conditions where the ADP-sensitive phosphoenzyme intermediate predominated in the wild-type Ca(2+)-ATPase. The rate of dephosphorylation of the ADP-insensitive phosphoenzyme intermediate formed through the forward reaction with ATP, or in the "backdoor" reaction with Pi, was reduced severalfold in the mutant relative to the dephosphorylation rate measured in the wild type, but there was no significant difference between the mutant and the wild type with respect to the apparent affinity for Pi measured under equilibrium conditions. The mutant was much less susceptible to inhibition by vanadate than the wild type, under equilibrium conditions as well as during turnover with ATP and Ca2+. These observations suggest that the transition state in the hydrolysis of the aspartyl phosphate bond in the ADP-insensitive phosphoenzyme intermediate was destabilized in the mutant.
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Affiliation(s)
- J P Andersen
- Danish Biomembrane Research Centre, University of Aarhus
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32
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Kalabokis VN, Hardwicke PM. Effect of the biochemical state of the Ca-ATPase protein of scallop sarcoplasmic reticulum on its interaction with trans-parinaric acid. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1147:35-41. [PMID: 8466929 DOI: 10.1016/0005-2736(93)90313-o] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The polyene fluorescent probe trans-parinaric acid (tPA) was used to compare lipid-protein interactions in the scallop fragmented sarcoplasmic reticulum (FSR) between biochemical states where the Ca-ATPase molecules were arranged differently in the membrane and had different tertiary conformations. The state of the bulk lipid phase was examined over the temperature range -3 to +32 degrees C by exciting the tPA directly at 320 nm. The state of the system close to the Ca-ATPase protein was followed over the same temperature range by indirectly exciting the tPA through resonance energy transfer from the Ca-ATPase protein, with approximately one twenty-fifth the quantum yield of the directly excited probe. Raising the tPA/lipid ratio in the membrane to high levels (approx. 1:9), caused the quantum yield of indirectly excited tPA to reach a maximum, which may reflect saturation of the annular lipid phase with the probe, or contribution to the fluorescence from indirectly excited tPA bound directly to the protein. In the presence of 0.1 M KCl, a thermal perturbation was observed at approx. 7 degrees C using indirect excitation when the Ca(2+)-binding sites on the Ca-ATPase were occupied, and the subunits were disorganized. This transition was not detected in the presence of 0.1 M KCl and EGTA, when the Ca(2+)-binding sites were empty, and the Ca-ATPase subunits were organized in dimeric arrays. The transition seen with the E1(Ca2+)2 form of the membrane may involve an event at the protein/lipid interface, or a change in the environment of tPA bound to the Ca-ATPase. The temperature at which the perturbation occurs is close to that of a discontinuity in the Arrhenius plot of the Ca-ATPase enzyme activity determined in the presence of 0.1 M KCl (Kalabokis, V.N. and Hardwicke, P.M.D. (1988) J. Biol. Chem. 263, 15184-15188). No perturbation was observed in the bulk properties of the lipid component of the membrane in either the E1(Ca2+)2 or E2 states.
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Affiliation(s)
- V N Kalabokis
- Department of Medical Biochemistry, Southern Illinois University, Carbondale
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33
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Bigelow DJ, Inesi G. Contributions of chemical derivatization and spectroscopic studies to the characterization of the Ca2+ transport ATPase of sarcoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1113:323-38. [PMID: 1450205 DOI: 10.1016/0304-4157(92)90005-u] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- D J Bigelow
- Department of Biochemistry, University of Kansas, Lawrence
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34
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Blasie JK, Asturias FJ, DeLong LJ. Time-resolved X-ray diffraction studies on the mechanism of active Ca2+ transport by the sarcoplasmic reticulum Ca2+ ATPase. Ann N Y Acad Sci 1992; 671:11-8. [PMID: 1288319 DOI: 10.1111/j.1749-6632.1992.tb43780.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- J K Blasie
- Department of Chemistry, University of Pennsylvania, Philadelphia 19104
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35
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Inesi G, Cantilina T, Yu X, Nikic D, Sagara Y, Kirtley ME. Long-range intramolecular linked functions in activation and inhibition of SERCA ATPases. Ann N Y Acad Sci 1992; 671:32-47; discussion 48. [PMID: 1288328 DOI: 10.1111/j.1749-6632.1992.tb43782.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- G Inesi
- Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore 21201
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36
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Fujimori T, Jencks W. Binding of two Sr2+ ions changes the chemical specificities for phosphorylation of the sarcoplasmic reticulum calcium ATPase through a stepwise mechanism. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)36987-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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37
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Henao F, Orlowski S, Merah Z, Champeil P. The metal sites on sarcoplasmic reticulum membranes that bind lanthanide ions with the highest affinity are not the ATPase Ca2+ transport sites. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50018-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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38
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Bondon A, Tiffoche C, Simonneaux G, Le Pennec JP, Jego P. A possible calcium binding site in animal lectins: a 1H-NMR study of the interaction between lanthanides and a synthetic peptide from a highly conserved domain of Pleurodeles lectin. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1135:19-26. [PMID: 1591269 DOI: 10.1016/0167-4889(92)90161-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1H-NMR techniques have been used to study the metal binding properties of a synthetic peptide of 15 amino acids corresponding to a highly conserved domain of Pleurodeles lectin. The addition of lanthanum chloride or praseodymium chloride in a peptide solution induces some conformational changes as displayed by several concerted variations of peptide resonances. The Ln3+ concentration dependence of the chemical shifts was used to calculate the Ln3+ binding constants. The dissociation constants of 95 microM and 280 microM were found for La3+ and Pr3+, respectively.
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Affiliation(s)
- A Bondon
- Laboratoire de Chimie Organométallique et Biologique, URA CNRS No. 415, Université de Rennes I, France
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39
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Bigelow D, Squier T, Inesi G. Phosphorylation-dependent changes in the spatial relationship between Ca-ATPase polypeptide chains in sarcoplasmic reticulum membranes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50521-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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40
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Kalabokis V, Bozzola J, Castellani L, Hardwicke P. A possible role for the dimer ribbon state of scallop sarcoplasmic reticulum. Dimmer ribbons are associated with stabilization of the Ca(2+)-free Ca-ATPase. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54742-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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41
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Ogurusu T, Wakabayashi S, Shigekawa M. Functional characterization of lanthanide binding sites in the sarcoplasmic reticulum Ca(2+)-ATPase: do lanthanide ions bind to the calcium transport site? Biochemistry 1991; 30:9966-73. [PMID: 1832958 DOI: 10.1021/bi00105a022] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Gd3+ binding sites on the purified Ca(2+)-ATPase of sarcoplasmic reticulum were characterized at 2 and 6 degrees C and pH 7.0 under conditions in which 45Ca2+ and 54Mn2+ specifically labeled the calcium transport site and the catalytic site of the enzyme, respectively. We detected several classes of Gd3+ binding sites that affected enzyme function: (a) Gd3+ exchanged with 54Mn2+ of the 54MnATP complex bound at the catalytic site. This permitted slow phosphorylation of the enzyme when two Ca2+ ions were bound at the transport site. The Gd3+ ion bound at the catalytic site inhibited decomposition of the ADP-sensitive phosphoenzyme. (b) High-affinity binding of Gd3+ to site(s) distinct from both the transport site and the catalytic site inhibited the decomposition of the ADP-sensitive phosphoenzyme. (c) Gd3+ enhanced 4-nitro-2,1,3-benzoxadiazole (NBD) fluorescence in NBD-modified enzyme by probably binding to the Mg2+ site that is distinct from both the transport site and the catalytic site. (d) Gd3+ inhibited high-affinity binding of 45Ca2+ to the transport site not by directly competing with Ca2+ for the transport site but by occupying site(s) other than the transport site. This conclusion was based mainly on the result of kinetic analysis of displacement of the enzyme-bound 45Ca2+ ions by Gd3+ and vice versa, and the inability of Gd3+ to phosphorylate the enzyme under conditions in which GdATP served as a substrate. These results strongly suggest that Ln3+ ions cannot be used as probes to structurally and functionally characterize the calcium transport site on the Ca(2+)-ATPase.
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Affiliation(s)
- T Ogurusu
- Department of Molecular Physiology, National Cardiovascular Center Research Institute, Osaka, Japan
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42
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P-type ion pumps: structure determination may soon catch up with structure predictions. Curr Opin Struct Biol 1991. [DOI: 10.1016/s0959-440x(05)80077-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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43
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Characterization of lanthanides as competitors of Na+ and K+ in occlusion sites of renal (Na+,K+)-ATPase. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98562-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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44
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Bigelow DJ, Inesi G. Frequency-domain fluorescence spectroscopy resolves the location of maleimide-directed spectroscopic probes within the tertiary structure of the Ca-ATPase of sarcoplasmic reticulum. Biochemistry 1991; 30:2113-25. [PMID: 1825607 DOI: 10.1021/bi00222a016] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have used fluorescence spectroscopy to characterize three covalently bound spectroscopic maleimide derivatives with respect to their location within the tertiary structure of the Ca-ATPase of sarcoplasmic reticulum (SR). These derivatives include (1) 2-(4'-maleimidoanilino)naphthalene-6-sulfonic acid, (2) 4-(dimethylamino)azobenzene-4'-maleimide, and (3) fluorescein 5'-maleimide. Biochemical assays demonstrate that modification with any of these three derivatives results in the same functional effects, observed following derivatization of cysteines 344 and 364 by N-ethylmaleimide [Saito-Nakatsuka et al. (1987) J. Biochem. (Tokyo) 101, 365-376]. These residues bracket the ATPase's phosphorylation site (Asp 351) and thus may provide spectroscopic probes of the protein's conformation in this essential region. In agreement with sequencing results, SDS-polyacrylamide gels show that maleimide-modified SR exhibits fluorescence exclusively on the A1 tryptic fragment of the Ca-ATPase. Extensive tryptic digestion followed by centrifugation demonstrates essentially all of the fluorescence was associated with the soluble rather than insoluble (membrane-associated) peptides, confirming the predicted extramembranous location of these residues. Utilizing frequency-domain fluorescence spectroscopy, we were able to recover the transient effects associated with a distribution of donor-acceptor distances. We find from these fluorescence resonance energy transfer measurements that covalently bound maleimide probes are 36 A apart, independent of whether a discrete distance is assumed or a distance distribution model is utilized, in which the conformational variability of the protein is taken into account. While a unimodal distance distribution is adequate to describe the intensity decay associated with maleimide-directed donor-acceptor pairs, a bimodal distribution of distances is necessary to describe the frequency response associated with the energy transfer between maleimide-directed chromophores and other covalently bound probes on the Ca-ATPase, consistent with the large spatial separation observed between maleimides. We recover mean distances of 42 and 77 A between maleimide sites and bound FITC (Lys 515) and mean distances of 28 and 37 A between the maleimide- and the iodoacetamide-directed probes (Cys 670 and 674, whose close proximity approximates a single locus). The measured distances are presented in a model and have permitted us to describe a unique arrangement of these covalently bound probes within both the secondary and tertiary structure of the Ca-ATPase. The resolution inherent in the frequency-domain fluorescence technique to multiple donor-acceptor distances should be generally applicable to a wide range of biological systems in which specific labeling of single unique donor-acceptor sites is not feasible.
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Affiliation(s)
- D J Bigelow
- Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore 21201
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45
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Missiaen L, Wuytack F, Raeymaekers L, De Smedt H, Droogmans G, Declerck I, Casteels R. Ca2+ extrusion across plasma membrane and Ca2+ uptake by intracellular stores. Pharmacol Ther 1991; 50:191-232. [PMID: 1662401 DOI: 10.1016/0163-7258(91)90014-d] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The aim of this review is to summarize the various systems that remove Ca2+ from the cytoplasm. We will initially focus on the Ca2+ pump and the Na(+)-Ca2+ exchanger of the plasma membrane. We will review the functional regulation of these systems and the recent progress obtained with molecular-biology techniques, which pointed to the existence of different isoforms of the Ca2+ pump. The Ca2+ pumps of the sarco(endo)plasmic reticulum will be discussed next, by summarizing the discoveries obtained with molecular-biology techniques, and by reviewing the physiological regulation of these proteins. We will finally briefly review the mitochondrial Ca(2+)-uptake mechanism.
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Affiliation(s)
- L Missiaen
- Laboratory of Molecular Signalling, Department of Zoology, Cambridge, U.K
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