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Sugio Y, Yamagami R, Shigi N, Hori H. A selective and sensitive detection system for 4-thiouridine modification in RNA. RNA (NEW YORK, N.Y.) 2023; 29:241-251. [PMID: 36411056 PMCID: PMC9891261 DOI: 10.1261/rna.079445.122] [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: 09/07/2022] [Accepted: 11/14/2022] [Indexed: 06/16/2023]
Abstract
4-Thiouridine (s4U) is a modified nucleoside, found at positions 8 and 9 in tRNA from eubacteria and archaea. Studies of the biosynthetic pathway and physiological role of s4U in tRNA are ongoing in the tRNA modification field. s4U has also recently been utilized as a biotechnological tool for analysis of RNAs. Therefore, a selective and sensitive system for the detection of s4U is essential for progress in the fields of RNA technologies and tRNA modification. Here, we report the use of biotin-coupled 2-aminoethyl-methanethiosulfonate (MTSEA biotin-XX) for labeling of s4U and demonstrate that the system is sensitive and quantitative. This technique can be used without denaturation; however, addition of a denaturation step improves the limit of detection. Thermus thermophilus tRNAs, which abundantly contain 5-methyl-2-thiouridine, were tested to investigate the selectivity of the MTSEA biotin-XX s4U detection system. The system did not react with 5-methyl-2-thiouridine in tRNAs from a T. thermophilus tRNA 4-thiouridine synthetase (thiI) gene deletion strain. Thus, the most useful advantage of the MTSEA biotin-XX s4U detection system is that MTSEA biotin-XX reacts only with s4U and not with other sulfur-containing modified nucleosides such as s2U derivatives in tRNAs. Furthermore, the MTSEA biotin-XX s4U detection system can analyze multiple samples in a short time span. The MTSEA biotin-XX s4U detection system can also be used for the analysis of s4U formation in tRNA. Finally, we demonstrate that the MTSEA biotin-XX system can be used to visualize newly transcribed tRNAs in S. cerevisiae cells.
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Affiliation(s)
- Yuzuru Sugio
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Ryota Yamagami
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Naoki Shigi
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Koto-ku, Tokyo 135-0064, Japan
| | - Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan
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Hori H. Transfer RNA Modification Enzymes with a Thiouridine Synthetase, Methyltransferase and Pseudouridine Synthase (THUMP) Domain and the Nucleosides They Produce in tRNA. Genes (Basel) 2023; 14:genes14020382. [PMID: 36833309 PMCID: PMC9957541 DOI: 10.3390/genes14020382] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/25/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
The existence of the thiouridine synthetase, methyltransferase and pseudouridine synthase (THUMP) domain was originally predicted by a bioinformatic study. Since the prediction of the THUMP domain more than two decades ago, many tRNA modification enzymes containing the THUMP domain have been identified. According to their enzymatic activity, THUMP-related tRNA modification enzymes can be classified into five types, namely 4-thiouridine synthetase, deaminase, methyltransferase, a partner protein of acetyltransferase and pseudouridine synthase. In this review, I focus on the functions and structures of these tRNA modification enzymes and the modified nucleosides they produce. Biochemical, biophysical and structural studies of tRNA 4-thiouridine synthetase, tRNA methyltransferases and tRNA deaminase have established the concept that the THUMP domain captures the 3'-end of RNA (in the case of tRNA, the CCA-terminus). However, in some cases, this concept is not simply applicable given the modification patterns observed in tRNA. Furthermore, THUMP-related proteins are involved in the maturation of other RNAs as well as tRNA. Moreover, the modified nucleosides, which are produced by the THUMP-related tRNA modification enzymes, are involved in numerous biological phenomena, and the defects of genes for human THUMP-related proteins are implicated in genetic diseases. In this review, these biological phenomena are also introduced.
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Affiliation(s)
- Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan
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The [4Fe-4S] cluster of sulfurtransferase TtuA desulfurizes TtuB during tRNA modification in Thermus thermophilus. Commun Biol 2020; 3:168. [PMID: 32265486 PMCID: PMC7138817 DOI: 10.1038/s42003-020-0895-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 03/06/2020] [Indexed: 11/23/2022] Open
Abstract
TtuA and TtuB are the sulfurtransferase and sulfur donor proteins, respectively, for biosynthesis of 2-thioribothymidine (s2T) at position 54 of transfer RNA (tRNA), which is responsible for adaptation to high temperature environments in Thermus thermophilus. The enzymatic activity of TtuA requires an iron-sulfur (Fe-S) cluster, by which a sulfur atom supplied by TtuB is transferred to the tRNA substrate. Here, we demonstrate that the Fe-S cluster directly receives sulfur from TtuB through its inherent coordination ability. TtuB forms a [4Fe-4S]-TtuB intermediate, but that sulfur is not immediately released from TtuB. Further desulfurization assays and mutation studies demonstrated that the release of sulfur from the thiocarboxylated C-terminus of TtuB is dependent on adenylation of the substrate tRNA, and the essential residue for TtuB desulfurization was identified. Based on these findings, the molecular mechanism of sulfur transfer from TtuB to Fe-S cluster is proposed. Chen et al. demonstrate how the Fe-S cluster receives sulfur from TtuB, a ubiquitin-like sulfur donor during tRNA modification. They find that the release of sulfur from the thiocarboxylated C-terminus of TtuB depends on the adenylation of the substrate tRNA. This study provides molecular insights into the sulfur modification of tRNA.
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Diniz RR, Paiva JP, Aquino RM, Gonçalves TCW, Leitão AC, Santos BAMC, Pinto AV, Leandro KC, de Pádula M. Saccharomyces cerevisiae strains as bioindicators for titanium dioxide sunscreen photoprotective and photomutagenic assessment. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2019; 198:111584. [PMID: 31434036 DOI: 10.1016/j.jphotobiol.2019.111584] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/01/2019] [Accepted: 08/07/2019] [Indexed: 11/15/2022]
Abstract
Although several short-term assays are available for cosmetic photosafety assessment, cell models are usually highly sensitive to UV radiation, tending to overestimate both phototoxic and photomutagenic risks. In addition, these assays are performed with UV doses/fluences that do not correspond to actual environmental conditions. In this sense, Saccharomyces cerevisiae has already proved to be an interesting tool to predict photomutagenic potential of several compounds, including sunscreens. Yeast can support environmental UVB doses compatible with human daily sunlight exposure, allowing the use of irradiation sources to faithfully mimic the external conditions of ambient sunlight. Herein, we used a set of S. cerevisiae mutant strains sensitive to UVA, UVB and Solar Simulated Light sources in order to evaluate their potential as bioindicators for sunscreen development. The bioindicator potential of the strains was tested with the widely-used titanium dioxide inorganic sunscreen. The AWP001 (yno1) and LPW002 (ogg1yno1) strains obtained in this study stood out as promising experimental tools for the validation of this assay. Overall, our results evidenced a set of S. cerevisiae strains particularly useful for evaluating both photoprotective (efficacy) and photo/antiphotomutagenic (safety) potential of UV filters, meeting the industries and regulatory agencies demand for robust and efficient in vitro screening tests.
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Affiliation(s)
- Raiane R Diniz
- Instituto Nacional de Controle de Qualidade em Saúde (INCQS), Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil; Laboratório de Microbiologia e Avaliação Genotóxica (LAMIAG), Faculdade de Farmácia, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
| | - Juliana P Paiva
- Laboratório de Microbiologia e Avaliação Genotóxica (LAMIAG), Faculdade de Farmácia, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
| | - Renan M Aquino
- Laboratório de Microbiologia e Avaliação Genotóxica (LAMIAG), Faculdade de Farmácia, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
| | - Tula C W Gonçalves
- Laboratório de Microbiologia e Avaliação Genotóxica (LAMIAG), Faculdade de Farmácia, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
| | - Alvaro C Leitão
- Instituto de Biofísica Carlos Chagas Filho, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
| | - Bianca Aloise M C Santos
- Laboratório de Planejamento Farmacêutico e Simulação Computacional (LaPFarSC), Faculdade de Farmácia, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
| | - Alicia V Pinto
- Instituto Nacional de Controle de Qualidade em Saúde (INCQS), Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil
| | - Katia C Leandro
- Instituto Nacional de Controle de Qualidade em Saúde (INCQS), Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil
| | - Marcelo de Pádula
- Laboratório de Microbiologia e Avaliação Genotóxica (LAMIAG), Faculdade de Farmácia, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil.
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Hori H, Kawamura T, Awai T, Ochi A, Yamagami R, Tomikawa C, Hirata A. Transfer RNA Modification Enzymes from Thermophiles and Their Modified Nucleosides in tRNA. Microorganisms 2018; 6:E110. [PMID: 30347855 PMCID: PMC6313347 DOI: 10.3390/microorganisms6040110] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/17/2018] [Accepted: 10/17/2018] [Indexed: 12/11/2022] Open
Abstract
To date, numerous modified nucleosides in tRNA as well as tRNA modification enzymes have been identified not only in thermophiles but also in mesophiles. Because most modified nucleosides in tRNA from thermophiles are common to those in tRNA from mesophiles, they are considered to work essentially in steps of protein synthesis at high temperatures. At high temperatures, the structure of unmodified tRNA will be disrupted. Therefore, thermophiles must possess strategies to stabilize tRNA structures. To this end, several thermophile-specific modified nucleosides in tRNA have been identified. Other factors such as RNA-binding proteins and polyamines contribute to the stability of tRNA at high temperatures. Thermus thermophilus, which is an extreme-thermophilic eubacterium, can adapt its protein synthesis system in response to temperature changes via the network of modified nucleosides in tRNA and tRNA modification enzymes. Notably, tRNA modification enzymes from thermophiles are very stable. Therefore, they have been utilized for biochemical and structural studies. In the future, thermostable tRNA modification enzymes may be useful as biotechnology tools and may be utilized for medical science.
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Affiliation(s)
- Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Takuya Kawamura
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Takako Awai
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Anna Ochi
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Ryota Yamagami
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Chie Tomikawa
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Akira Hirata
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
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Biochemical and structural characterization of oxygen-sensitive 2-thiouridine synthesis catalyzed by an iron-sulfur protein TtuA. Proc Natl Acad Sci U S A 2017; 114:4954-4959. [PMID: 28439027 DOI: 10.1073/pnas.1615585114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two-thiouridine (s2U) at position 54 of transfer RNA (tRNA) is a posttranscriptional modification that enables thermophilic bacteria to survive in high-temperature environments. s2U is produced by the combined action of two proteins, 2-thiouridine synthetase TtuA and 2-thiouridine synthesis sulfur carrier protein TtuB, which act as a sulfur (S) transfer enzyme and a ubiquitin-like S donor, respectively. Despite the accumulation of biochemical data in vivo, the enzymatic activity by TtuA/TtuB has rarely been observed in vitro, which has hindered examination of the molecular mechanism of S transfer. Here we demonstrate by spectroscopic, biochemical, and crystal structure analyses that TtuA requires oxygen-labile [4Fe-4S]-type iron (Fe)-S clusters for its enzymatic activity, which explains the previously observed inactivation of this enzyme in vitro. The [4Fe-4S] cluster was coordinated by three highly conserved cysteine residues, and one of the Fe atoms was exposed to the active site. Furthermore, the crystal structure of the TtuA-TtuB complex was determined at a resolution of 2.5 Å, which clearly shows the S transfer of TtuB to tRNA using its C-terminal thiocarboxylate group. The active site of TtuA is connected to the outside by two channels, one occupied by TtuB and the other used for tRNA binding. Based on these observations, we propose a molecular mechanism of S transfer by TtuA using the ubiquitin-like S donor and the [4Fe-4S] cluster.
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Chen M, Narai S, Omura N, Shigi N, Chimnaronk S, Tanaka Y, Yao M. Crystallographic study of the 2-thioribothymidine-synthetic complex TtuA-TtuB from Thermus thermophilus. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2016; 72:777-781. [PMID: 27710943 DOI: 10.1107/s2053230x16014242] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/07/2016] [Indexed: 11/10/2022]
Abstract
The ubiquitin-like protein TtuB is a sulfur carrier for the biosynthesis of 2-thioribothymidine (s2T) at position 54 in some thermophilic bacterial tRNAs. TtuB captures a S atom at its C-terminus as a thiocarboxylate and transfers it to tRNA by the transferase activity of TtuA. TtuB also functions to suppress s2T formation by forming a covalent bond with TtuA. To explore how TtuB interacts with TtuA and switches between these two different functions, high-resolution structure analysis of the TtuA-TtuB complex is required. In this study, the TtuA-TtuB complex from Thermus thermophilus was expressed, purified and crystallized. To mimic the thiocarboxylated TtuB, the C-terminal Gly residue was replaced with Cys (G65C) to obtain crystals of the TtuA-TtuB complex. A Zn-MAD data set was collected to a resolution of 2.5 Å. MAD analysis successfully determined eight Zn sites, and a partial structure model composed of four TtuA-TtuB complexes in the asymmetric unit was constructed.
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Affiliation(s)
- Minghao Chen
- Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Shun Narai
- Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Naoki Omura
- Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Naoki Shigi
- Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Sarin Chimnaronk
- Faculty of Advanced Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Yoshikazu Tanaka
- Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Min Yao
- Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
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de Azevedo LV, de Barros HL, Keim CN, Acosta-Avalos D. Effect of light wavelength on motility and magnetic sensibility of the magnetotactic multicellular prokaryote 'Candidatus Magnetoglobus multicellularis'. Antonie van Leeuwenhoek 2013; 104:405-12. [PMID: 23828178 DOI: 10.1007/s10482-013-9964-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 06/27/2013] [Indexed: 11/29/2022]
Abstract
'Candidatus Magnetoglobus multicellularis' is a magnetotactic microorganism composed of several bacterial cells. Presently, it is the best known multicellular magnetotactic prokaryote (MMP). Recently, it has been observed that MMPs present a negative photoresponse to high intensity ultraviolet and violet-blue light. In this work, we studied the movement of 'Candidatus Magnetoglobus multicellularis' under low intensity light of different wavelengths, measuring the average velocity and the time to reorient its trajectory when the external magnetic field changes its direction (U-turn time). Our results show that the mean average velocity is higher for red light (628 nm) and lower for green light (517 nm) as compared to yellow (596 nm) and blue (469 nm) light, and the U-turn time decreased for green light illumination. The light wavelength velocity dependence can be understood as variation in flagella rotation speed, being increased by the red light and decreased by the green light relative to yellow and blue light. It is suggested that the dependence of the U-turn time on light wavelength can be considered a form of light-dependent magnetotaxis, because this time represents the magnetic sensibility of the magnetotactic microorganisms. The cellular and molecular mechanisms for this light-dependent velocity and magnetotaxis are unknown and deserve further studies to understand the biochemical interactions and the ecological roles of the different mechanisms of taxis in MMPs.
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Affiliation(s)
- Lyvia Vidinho de Azevedo
- Centro Brasileiro de Pesquisas Fisicas-CBPF, Rua Xavier Sigaud 150, Urca, Rio de Janeiro, Brazil
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Functional Analysis of Bacillus subtilis Genes Involved in the Biosynthesis of 4-Thiouridine in tRNA. J Bacteriol 2012; 194:4933-40. [PMID: 22773787 DOI: 10.1128/jb.00842-12] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ThiI has been identified as an essential enzyme involved in the biosynthesis of thiamine and the tRNA thionucleoside modification, 4-thiouridine. In Escherichia coli and Salmonella enterica, ThiI acts as a sulfurtransferase, receiving the sulfur donated from the cysteine desulfurase IscS and transferring it to the target molecule or additional sulfur carrier proteins. However, in Bacillus subtilis and most species from the Firmicutes phylum, ThiI lacks the rhodanese domain that contains the site responsible for the sulfurtransferase activity. The lack of the gene encoding for a canonical IscS cysteine desulfurase and the presence of a short sequence of ThiI in these bacteria pointed to mechanistic differences involving sulfur trafficking reactions in both biosynthetic pathways. Here, we have carried out functional analysis of B. subtilis thiI and the adjacent gene, nifZ, encoding for a cysteine desulfurase. Gene inactivation experiments in B. subtilis indicate the requirement of ThiI and NifZ for the biosynthesis of 4-thiouridine, but not thiamine. In vitro synthesis of 4-thiouridine by ThiI and NifZ, along with labeling experiments, suggests the occurrence of an alternate transient site for sulfur transfer, thus obviating the need for a rhodanese domain. In vivo complementation studies in E. coli IscS- or ThiI-deficient strains provide further support for specific interactions between NifZ and ThiI. These results are compatible with the proposal that B. subtilis NifZ and ThiI utilize mechanistically distinct and mutually specific sulfur transfer reactions.
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Berney M, Weilenmann HU, Egli T. Adaptation to UVA radiation of E. coli growing in continuous culture. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2006; 86:149-59. [PMID: 17055285 DOI: 10.1016/j.jphotobiol.2006.08.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Revised: 08/15/2006] [Accepted: 08/20/2006] [Indexed: 11/30/2022]
Abstract
Adaptive responses of bacteria to physical or chemical stresses in the laboratory or in the environment are of great interest. Here we investigated the ability of Escherichia coli growing in continuous culture to adapt to UVA radiation. It was shown that E. coli indeed expressed an adaptive response to UVA irradiation at an intensity of 50W/m(2). Cells grown in continuous culture with complex medium (diluted Luria Bertani broth) at dilution rates of 0.7h(-1), 0.5h(-1) and 0.3h(-1) were able to maintain growth under UVA irradiation after a transient reduction of specific growth rate and recovery. In contrast, slow-growing cells (D=0.05h(-1)) were unable to induce enough protection capacity to maintain growth under UVA irradiation. We propose that faster growing E. coli cells have a higher adaptive flexibility to UVA light-stress than slow-growing cells. Furthermore it was shown with flow cytometry and viability stains that at a dilution rate of 0.3h(-1) only a small fraction (1%) of the initial cell population survived UVA light-stress. Adapted cells were significantly larger (30%) than unstressed cells and had a lower growth yield. Furthermore, efflux pump activity was diminished in adapted cells. In a second irradiation period (after omitting UVA irradiation for 70h) adapted cells were able to trigger the adaptive response twice as fast. Additionally, this study shows that continuous cultivation with direct stress application allows reproducible investigation of the physiological and possibly also molecular mechanisms during adaptation of E. coli populations to UVA light.
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Affiliation(s)
- Michael Berney
- Swiss Federal Institute of Aquatic Science and Technology, Eawag, Environmental Microbiology, P.O. Box 611, CH-8600 Dübendorf, Switzerland
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Oppezzo OJ, Pizarro RA. Inhibition of sulfur incorporation to transfer RNA by ultraviolet-A radiation in Escherichia coli. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2003; 71:69-75. [PMID: 14705641 DOI: 10.1016/j.jphotobiol.2003.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
tRNA sulfurtransferase activity was assayed in Escherichia coli cell extracts obtained from bacterial suspensions exposed to a sub-lethal dose of ultraviolet-A radiation (fluence 148 kJ m(-2)) imparted at a low fluence rate (41 W m(-2)). We found that the irradiation reduced the enzymatic activity to one fourth of the control value, indicating that ultraviolet-A exposure inhibits the synthesis of 4-thiouridine, the most abundant thionucleoside in E. coli tRNA. Changes in the tRNA content of 4-thiouridine and its derived photoproduct 5-(4'-pyrimidin 2'-one) cytosine were studied in bacteria growing under ultraviolet-A irradiation. In these conditions the accumulation of photoproduct was limited, and the kinetics of this process was non-coincident with disappearance of 4-thiouridine. The results, which are compatible with the fact that ultraviolet-A induces an inhibition of the 4-thiouridine synthesis, suggest that the effect of radiation on tRNA modification is relevant to tRNA photo-inactivation in growing bacteria.
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Affiliation(s)
- Oscar J Oppezzo
- Departamento de Radiobiología, Comisión Nacional de Energía Atómica, Av. General Paz 1499, 1650 General San Martín, Buenos Aires, Argentina.
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Caldeira de Araujo A, Favre A. Partial tRNA deacylation specifically triggers Escherichia coli cell volume reduction. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1987; 1:13-31. [PMID: 3149980 DOI: 10.1016/1011-1344(87)80003-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Limitation of Escherichia coli cell growth rate either by means of continuous 366 nm illumination, which is known to decrease the in vivo acylation level of some tRNA species, or by means of specific inhibitors of tRNA acylation allows the division rate to remain unchanged for a few generations, resulting in cell volume reduction. In contrast the cell volume remains stable or increases after treatment with inhibitors of DNA replication and transcription, or with drugs acting at any other step of protein synthesis. The conclusion that limiting acylation of some tRNA species is the triggering event is confirmed by the use of thermosensitive mutants of aminoacyl-tRNA synthetases or of tRNA (the divE strain mutated in the tRNA1Ser gene). Other cellular responses modulate the expression of cell volume reduction. The relA+ stringent response helps expression of the effect but does not appear to be strictly required. However, cell volume reduction may be masked under conditions triggering the SOS response. The data suggest that tRNA acylation is one of the major steps where cells sense change in their nutrient environment.
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Hajnsdorf E, Favre A. Metabolism of tRNAs in growing cells of Escherichia coli illuminated with near-ultraviolet light. Photochem Photobiol 1986; 43:157-64. [PMID: 3517895 DOI: 10.1111/j.1751-1097.1986.tb09508.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Favre A, Hajnsdorf E, Thiam K, Caldeira de Araujo A. Mutagenesis and growth delay induced in Escherichia coli by near-ultraviolet radiations. Biochimie 1985; 67:335-42. [PMID: 2412594 DOI: 10.1016/s0300-9084(85)80076-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The literature relating to genetic changes induced in Escherichia coli by near-ultraviolet radiations is reviewed and summarized: i) these radiations are much less mutagenic than would be expected from the known level of DNA damage, ii) pre-illumination with near-UV light antagonizes the mutagenic effect of UV (254 nm) light. In agreement with these findings, the SOS functions are not induced by near-UV radiations. Furthermore prior exposure of cells to near-UV light inhibits the subsequent 254 nm induction of the SOS response. Among the several hypothesis considered to explain these observations, one can be clearly favoured. Near-UV light triggers, at sublethal fluences, the growth delay effect. The target molecules, tRNAs, are photocrosslinked and some tRNA species become poor substrates in the acylation reaction. In vivo these tRNA molecules accumulate on the uncharged form, leading to a transient cessation of protein synthesis. The SOS response is inducible and as such requires protein synthesis. We therefore propose that near-ultraviolet radiations have a dual effect: i) they induce, mostly indirectly, DNA lesions which are potentially able to trigger the SOS response, ii) they prevent the expression of the SOS functions through the transient inhibition of protein synthesis (growth delay).
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