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Khudzari J, Fukuda SY, Shiraiwa Y, Iwamoto K. Kinetic properties of 137Cs uptake by the cesium-accumulating eustigmatophycean microalga. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:34460-34467. [PMID: 36509956 DOI: 10.1007/s11356-022-24573-6] [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: 03/10/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
Cesium-137 (137Cs) is one of the radioactive substances that was released into the environment as a result of the Fukushima nuclear disaster. Radiocesium exposure is of great concern due to its potential environmental implications. However, research on 137Cs removal using algae is still limited. This is the first report to describe the kinetic properties of 137Cs uptake by Vacuoliviride crystalliferum in the presence and absence of potassium. In this work, we studied the kinetic properties of 137Cs uptake using a freshwater microalga, V. crystalliferum (NIES 2860). We also analyzed the effects of temperature, light, and potassium (K) on the 137Cs uptake. Results showed that V. crystalliferum can remove up to 90% of 157 nM 137Cs within an hour. At 20 °C, the removal increased by up to 96%, compared to less than 10% at 5 °C. However, the removal was inhibited by nearly 90% in the dark compared to the removal in the light, implying that V. crystalliferum cells require energy to accumulate 137Cs. In the inhibition assay, K concentrations ranged from 0 to 500 µM and the inhibitory constant (Ki) for K was determined to be 16.7 µM. While in the uptake assay without potassium (- K), the Michaelis constant (Km) for Cs was 45 nM and increased to 283 nM by the addition of 20 µM potassium (+ K), indicating that V. crystalliferum had a high affinity for 137Cs. In addition, the maximum uptake velocity (Vmax) also increased from 6.75 to 21.10 nmol (mg Chl h)-1, implying the existence of Cs active transport system. In conclusion, V. crystalliferum is capable of removing radioactive 137Cs from the environment and the removal was favorable at both normal temperature and in the light.
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Affiliation(s)
- Jauharah Khudzari
- Algae and Biomass Research Laboratory, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia
| | - Shin-Ya Fukuda
- University of Tsukuba, Tsukuba, Ibaraki, 305-8577, Japan
| | | | - Koji Iwamoto
- Algae and Biomass Research Laboratory, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia.
- University of Tsukuba, Tsukuba, Ibaraki, 305-8577, Japan.
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Shi NQ, Li Y, Zhang Y, Shen N, Qi L, Wang SR, Qi XR. Intelligent "Peptide-Gathering Mechanical Arm" Tames Wild "Trojan-Horse" Peptides for the Controlled Delivery of Cancer Nanotherapeutics. ACS APPLIED MATERIALS & INTERFACES 2017; 9:41767-41781. [PMID: 29161013 DOI: 10.1021/acsami.7b15523] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Cell-penetrating peptides (CPPs), also called "Trojan-Horse" peptides, have been used for facilitating intracellular delivery of numerous diverse cargoes and even nanocarriers. However, the lack of targeting specificity ("wildness" or nonselectivity) of CPP-nanocarriers remains an intractable challenge for many in vivo applications. In this work, we used an intelligent "peptide-gathering mechanical arm" (Int PMA) to curb CPPs' wildness and enhance the selectivity of R9-liposome-based cargo delivery for tumor targeting. The peptide NGR, serving as a cell-targeting peptide for anchoring, and peptide PLGLAG, serving as a substrate peptide for deanchoring, were embedded in the Int PMA motif. The Int PMA construct was designed to be sensitive to tumor microenvironmental stimuli, including aminopeptidase N (CD13) and matrix metalloproteinases (MMP-2/9). Moreover, Int PMA could be specifically recognized by tumor tissues via CD13-mediated anchoring and released for cell entry by MMP-2/9-mediated deanchoring. To test the Int PMA design, a series of experiments were conducted in vitro and in vivo. Functional conjugates Int PMA-R9-poly(ethylene glycol) (PEG)2000-distearoylphosphatidyl-ethanolamine (DSPE) and R9-PEG2000-DSPE were synthesized by Michael addition reaction and were characterized by thin-layer chromatography and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. The Int PMA-R9-modified doxorubicin-loaded liposomes (Int PMA-R9-Lip-DOX) exhibited a proper particle diameter (approximately 155 nm) with in vitro sustained release characteristics. Cleavage assay showed that Int PMA-R9 peptide molecules could be cleaved by MMP-2/9 for completion of deanchoring. Flow cytometry and confocal microscopy studies indicated that Int PMA-R9-Lip-DOX can respond to both endogenous and exogenous stimuli in the presence/absence of excess MMP-2/9 and MMP-2/9 inhibitor (GM6001) and effectively function under competitive receptor-binding conditions. Moreover, Int PMA-R9-Lip-DOX generated more significant subcellular dispersions that were especially evident within endoplasmic reticulum (ER) and Golgi apparatus. Notably, Int PMA-R9-Lip-DOX could induce enhanced apoptosis, during which caspase 3/7 might be activated. In addition, Int PMA-R9-Lip-DOX displayed enhanced in vitro and in vivo antitumor efficacy versus "wild" R9-Lip-DOX. On the basis of investigations at the molecular level, cellular level, and animals' level, the control of Int PMA was effective and promoted selective delivery of R9-liposome cargo to the target site and reduced nonspecific uptake. This Int PMA-controlled strategy based on aminopeptidase-guided anchoring and protease-triggered deanchoring effectively curbed the wildness of CPPs and bolstered their effectiveness for in vivo delivery of nanotherapeutics. The specific nanocarrier delivery system used here could be adapted using a variety of intelligent designs based on combinations of multifunctional peptides that would specifically and preferentially bind to tumors versus nontumor tissues for tumor-localized accumulation in vivo. Thus, CPPs have a strong advantage for the development of intelligent nanomedicines for targeted tumor therapy.
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Affiliation(s)
- Nian-Qiu Shi
- State Key Laboratory of Medicinal Chemical Biology, Nankai University , Tianjin 300071, China
| | | | - Yong Zhang
- College of Life Science, Jilin University , 2699 Qianjin Street, Changchun 130012, Jilin Province, China
| | | | | | | | - Xian-Rong Qi
- Department of Pharmaceutics, School of Pharmaceutical Science, Peking University , Beijing 100191, China
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Miranda M, Bashi E, Vylkova S, Edgerton M, Slayman C, Rivetta A. Conservation and dispersion of sequence and function in fungal TRK potassium transporters: focus onCandida albicans. FEMS Yeast Res 2009; 9:278-92. [DOI: 10.1111/j.1567-1364.2008.00471.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Wongwisansri S, Laybourn PJ. Disruption of histone deacetylase gene RPD3 accelerates PHO5 activation kinetics through inappropriate Pho84p recycling. EUKARYOTIC CELL 2005; 4:1387-95. [PMID: 16087743 PMCID: PMC1214523 DOI: 10.1128/ec.4.8.1387-1395.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The histone deacetylase Rpd3p functions as a transcriptional repressor of a diverse set of genes, including PHO5. Here we describe a novel role for RPD3 in the regulation of phosphate transporter Pho84p retention in the cytoplasmic membrane. We show that under repressing conditions (with P(i)), PHO5 expression is increased in a pho4Delta rpd3Delta strain, demonstrating PHO regulatory pathway independence. However, the effect of RPD3 disruption on PHO5 activation kinetics is dependent on the PHO regulatory pathway. Upon switching to activating conditions (without P(i)), PHO5 transcripts accumulated more rapidly in rpd3Delta cells. This more rapid response correlates with a defect in phosphate uptake due to premature recycling of Pho84p, the high-affinity H+/PO4(3-) symporter. Thus, RPD3 also participates in PHO5 regulation through a previously unidentified effect on maintenance of high-affinity phosphate uptake during phosphate starvation. We propose that Rpd3p has a negative role in the regulation of Pho84p endocytosis.
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Affiliation(s)
- Sriwan Wongwisansri
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA
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Zvyagilskaya RA, Persson BL. A new alkalitolerant Yarrowia lipolytica yeast strain is a promising model for dissecting properties and regulation of Na+-dependent phosphate transport systems. BIOCHEMISTRY (MOSCOW) 2004; 69:1310-7. [PMID: 15627385 DOI: 10.1007/s10541-005-0016-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A newly isolated osmo-, salt-, and alkalitolerant Yarrowia lipolytica yeast strain is distinguished from other yeast species by its capacity to grow vigorously at alkaline pH values (9.7), which makes it a promising model organism for studying Na+-dependent phosphate transport systems in yeasts. Phosphate uptake by Y. lipolytica cells grown at pH 9.7 was mediated by several kinetically discrete Na+-dependent systems specifically activated by Na+. One of these, a low-affinity transporter, operated at high concentrations of extracellular phosphate. The other two, high-affinity systems, maximally active in phosphate-starved cells, were repressed or derepressed depending on the prevailing extracellular phosphate concentration and pH value. The contribution of Na+/P(i)-cotransport systems to the total cellular phosphate uptake progressively increased with increasing pH, reaching its maximum at pH >/= 9.
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Affiliation(s)
- R A Zvyagilskaya
- Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow 119071, Russia.
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Zhang S, Crow SA. Toxic effects of Ag(I) and Hg(II) on Candida albicans and C. maltosa: a flow cytometric evaluation. Appl Environ Microbiol 2001; 67:4030-5. [PMID: 11526001 PMCID: PMC93125 DOI: 10.1128/aem.67.9.4030-4035.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effects of Ag(I) and Hg(II) on membrane potential and integrity of cells of Candida albicans and C. maltosa were determined with a flow cytometric procedure that employed an anionic membrane potential-sensitive dye, bis-(1,3-dibutylbarbituric acid) trimethine oxonol, and a membrane integrity indicator, propidium iodide. The membrane potentials of cells of both species were reduced rapidly within 15 min of exposure to Ag(I). No threshold dose for Hg(II) existed, and cells of both species lost membrane potential gradually in Hg(II) solutions. Cells of both species lost membrane integrity more rapidly in Ag(I) solutions than in Hg(II) solutions. In Ag(I) solutions, the decrease in the numbers of cells recoverable in culture occurred at a rate similar to the rate of cell depolarization and membrane permeabilization. In Hg(II) solutions, loss of cell recoverability preceded the loss of membrane potential and membrane integrity. C. albicans, in contrast to C. maltosa, showed no loss of membrane integrity after exposure to Hg(II) solutions for 1 h. Different rates of binding of Ag(I) and Hg(II) between the two species suggest that the two ions target different primary sites.
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Affiliation(s)
- S Zhang
- Environmental Research Center, Department of Biology, Georgia State University, Atlanta, Georgia, USA
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Howitt SM, Udvardi MK. Structure, function and regulation of ammonium transporters in plants. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1465:152-70. [PMID: 10748252 DOI: 10.1016/s0005-2736(00)00136-x] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ammonium is an important source of nitrogen for plants. It is taken up by plant cells via ammonium transporters in the plasma membrane and distributed to intracellular compartments such as chloroplasts, mitochondria and vacuoles probably via different transporters in each case. Ammonium is generally not used for long-distance transport of nitrogen within the plant. Instead, most of the ammonium transported into plant cells is assimilated locally via glutamine synthetases in the cytoplasm and plastids. Ammonium is also produced by plant cells during normal metabolism, and ammonium transporters enable it to be moved from intracellular sites of production to sites of consumption. Ammonium can be generated de novo from molecular nitrogen (N(2)) by nitrogen-fixing bacteria in some plant cells, such as rhizobia in legume root nodule cells, and at least one ammonium transporter is implicated in the transfer of ammonium from the bacteria to the plant cytoplasm. Plant physiologists have described many of these ammonium transport processes over the last few decades. However, the genes and proteins that underlie these processes have been isolated and studied only recently. In this review, we consider in detail the molecular structure, function and regulation of plant ammonium transporters. We also attempt to reconcile recent discoveries at the molecular level with our knowledge of ammonium transport at the whole plant level.
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Affiliation(s)
- S M Howitt
- Division of Biochemistry and Molecular Biology, The Australian National University, Canberra, Australia
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Martinez P, Zvyagilskaya R, Allard P, Persson BL. Physiological regulation of the derepressible phosphate transporter in Saccharomyces cerevisiae. J Bacteriol 1998; 180:2253-6. [PMID: 9555914 PMCID: PMC107158 DOI: 10.1128/jb.180.8.2253-2256.1998] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The extracellular phosphate concentration permissive for the expression of different amounts of the active high-affinity Pho84 phosphate transporter in the plasma membrane as well as the PHO84 messenger RNA levels in low-phosphate-grown Saccharomyces cerevisiae cells is very narrow and essential for a tight regulation of the transporter. The Pho84 transporter undergoes a rapid degradation once the supply of phosphate and/or carbon source is exhausted.
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Affiliation(s)
- P Martinez
- A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow
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Hoptroff MJ, Thomas S, Avery SV. Influence of altered plasma membrane fatty acid composition on cesium transport characteristics and toxicity in Saccharomyces cerevisiae. Can J Microbiol 1997; 43:954-62. [PMID: 9396148 DOI: 10.1139/m97-137] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The influence of altered plasma membrane fatty acid composition on cesium uptake and toxicity was investigated in Saccharomyces cerevisiae. Detailed kinetic studies revealed that both the Vmax and Km values for Cs+ transport increased (by approximately twofold in the latter case) when S. cerevisiae was grown in medium supplemented with the polyunsaturated fatty acid linoleate. In addition, Cs+ uptake by linoleate-enriched cells was considerably less sensitive to the competitive effects of other monovalent cations (K+, Rb+, and NH4+) than that by unsupplemented cells. Stimulation of Cs+ uptake in the presence of certain K+ and Rb+ concentrations was only evident in linoleate-enriched S. cerevisiae. At 100 mM CsCl, the initial rate of Cs+ uptake was greater in linoleate-supplemented cells than in unsupplemented cells and this was reflected in a more rapid displacement of cellular K+. However, little difference in net Cs+ accumulation between linoleate-supplemented and unsupplemented cells was evident during prolonged incubation in buffer or during growth. Thus, Cs+ toxicity was similar in linoleate-supplemented and unsupplemented cells. The results were consistent with the Cs+ (K+) transport mechanism adopting an altered conformational state in linoleate-enriched S. cerevisiae.
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Affiliation(s)
- M J Hoptroff
- Department of Biology, Georgia State University, Atlanta 30303, USA
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Avery SV. Caesium accumulation by microorganisms: uptake mechanisms, cation competition, compartmentalization and toxicity. JOURNAL OF INDUSTRIAL MICROBIOLOGY 1995; 14:76-84. [PMID: 7766213 DOI: 10.1007/bf01569888] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The continued release of caesium radioisotopes into the environment has led to a resurgence of interest in microbe-Cs interactions. Caesium exists almost exclusively as the monovalent cation Cs+ in the natural environment. Although Cs+ is a weak Lewis acid that exhibits a low tendency to form complexes with ligands, its chemical similarity to the biologically essential alkali cation K+ facilitates high levels of metabolism-dependent intracellular accumulation. Microbial Cs+ (K+) uptake is generally mediated by monovalent cation transport systems located on the plasma membrane. These differ widely in specificity for alkali cations and consequently microorganisms display large differences in their ability to accumulate Cs+; Cs+ appears to have an equal or greater affinity than K+ for transport in certain microorganisms. Microbial Cs+ accumulation is markedly influenced by the presence of external cations, e.g. K+, Na+, NH4+ and H+, and is generally accompanied by an approximate stoichiometric exchange for intracellular K+. However, stimulation of growth of K(+)-starved microbial cultures by Cs+ is limited and it has been proposed that it is not the presence of Cs+ in cells that is growth inhibitory but rather the resulting loss of K+. Increased microbial tolerance to Cs+ may result from sequestration of Cs+ in vacuoles or changes in the activity and/or specificity of transport systems mediating Cs+ uptake. The precise intracellular target(s) for Cs(+)-induced toxicity has yet to be clearly defined, although certain internal structures, e.g. ribosomes, become unstable in the presence of Cs+ and Cs+ is known to substitute poorly for K+ in the activation of many K(+)-requiring enzymes.
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Affiliation(s)
- S V Avery
- School of Pure and Applied Biology, University of Wales College of Cardiff, UK
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Berhe A, Fristedt U, Persson BL. Expression and purification of the high-affinity phosphate transporter of Saccharomyces cerevisiae. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 227:566-72. [PMID: 7851439 DOI: 10.1111/j.1432-1033.1995.tb20426.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The plasma membrane high-affinity phosphate permease of Saccharomyces cerevisiae has been overproduced as a stable membrane-bound chimeric protein in Escherichia coli. Construction of a chimera between the permease and a peptide containing 10 consecutive histidine residues allowed selective binding of the chimera to a chelating column charged with Ni2+, and elution with imidazole in a high state of purity. Approximately 5 mg purified His10-permease was obtained from 3 g (wet mass) cells. The purified phosphate permease chimera catalyzes uncoupler-sensitive phosphate transport after reconstitution into proteoliposomes.
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Affiliation(s)
- A Berhe
- Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, University of Stockholm, Sweden
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