1
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Rajakumar T, Hossain MA, Stopka SA, Micoogullari Y, Ang J, Agar NYR, Hanna J. Dysregulation of ceramide metabolism causes phytoceramide-dependent induction of the unfolded protein response. Mol Biol Cell 2024; 35:ar117. [PMID: 39024283 DOI: 10.1091/mbc.e24-03-0121] [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] [Indexed: 07/20/2024] Open
Abstract
The unfolded protein response (UPR) detects and mitigates the harmful effects of dysregulated endoplasmic reticulum (ER) function. The UPR has been best characterized as a protein quality control response, and the sole UPR sensor in yeast, Ire1, is known to detect misfolded ER proteins. However, recent work suggests the UPR can also sense diverse defects within the ER membrane, including increased fatty acid saturation and altered phospholipid abundance. These and other lipid-related stimuli have been referred to as lipid bilayer stress and may be sensed independently through Ire1's transmembrane domain. Here, we show that the loss of Isc1, a phospholipase that catabolizes complex ceramides, causes UPR induction, even in the absence of exogenous stress. A series of chemical and genetic approaches identified a requirement for very long-chain fatty acid (VLCFA)-containing phytoceramides for UPR induction. In parallel, comprehensive lipidomics analyses identified large increases in the abundance of specific VLCFA-containing phytoceramides in the isc1Δ mutant. We failed to identify evidence of an accompanying defect in protein quality control or ER-associated protein degradation. These results extend our understanding of lipid bilayer stress in the UPR and provide a foundation for mechanistic investigation of this fascinating intersection between ceramide metabolism, membrane homeostasis, and the UPR.
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Affiliation(s)
- Tamayanthi Rajakumar
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - Md Amin Hossain
- Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - Sylwia A Stopka
- Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - Yagmur Micoogullari
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - Jessie Ang
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - Nathalie Y R Agar
- Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
| | - John Hanna
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115
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2
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Velez B, Walsh RM, Rawson S, Razi A, Adams L, Perez EF, Jiao F, Blickling M, Rajakumar T, Fung D, Huang L, Hanna J. Mechanism of autocatalytic activation during proteasome assembly. Nat Struct Mol Biol 2024; 31:1167-1175. [PMID: 38600323 DOI: 10.1038/s41594-024-01262-1] [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: 11/14/2023] [Accepted: 03/04/2024] [Indexed: 04/12/2024]
Abstract
Many large molecular machines are too elaborate to assemble spontaneously and are built through ordered pathways orchestrated by dedicated chaperones. During assembly of the core particle (CP) of the proteasome, where protein degradation occurs, its six active sites are simultaneously activated via cleavage of N-terminal propeptides. Such activation is autocatalytic and coupled to fusion of two half-CP intermediates, which protects cells by preventing activation until enclosure of the active sites within the CP interior. Here we uncover key mechanistic aspects of autocatalytic activation, which proceeds through alignment of the β5 and β2 catalytic triad residues, respectively, with these triads being misaligned before fusion. This mechanism contrasts with most other zymogens, in which catalytic centers are preformed. Our data also clarify the mechanism by which individual subunits can be added in a precise, temporally ordered manner. This work informs two decades-old mysteries in the proteasome field, with broader implications for protease biology and multisubunit complex assembly.
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Affiliation(s)
- Benjamin Velez
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Richard M Walsh
- Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Shaun Rawson
- Harvard Cryo-Electron Microscopy Center for Structural Biology, Harvard Medical School, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Aida Razi
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Lea Adams
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Erignacio Fermin Perez
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Fenglong Jiao
- Department of Physiology and Biophysics, University of California-Irvine, Irvine, CA, USA
| | - Marie Blickling
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Tamayanthi Rajakumar
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Darlene Fung
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - Lan Huang
- Department of Physiology and Biophysics, University of California-Irvine, Irvine, CA, USA
| | - John Hanna
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA.
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3
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Poudel B, Mullins J, Fiedler JD, Zhong S. Genome-Wide Association Study of Fungicide Sensitivity in a Fusarium graminearum Population Collected from North Dakota. PHYTOPATHOLOGY 2024; 114:1088-1096. [PMID: 38079375 DOI: 10.1094/phyto-05-23-0180-kc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Fusarium head blight is a destructive disease of small grains. The disease is predominantly caused by the haploid ascomycete fungus Fusarium graminearum in North America. To understand the genetics of quantitative traits for sensitivity to fungicides in this fungal pathogen, we conducted a genome-wide association study of sensitivity to two demethylation inhibition class fungicides, tebuconazole and prothioconazole, using an F. graminearum population of 183 isolates collected between 1981 and 2013 from North Dakota. Baseline sensitivity to tebuconazole and prothioconazole was established using 21 isolates collected between 1981 and 1994. Most fungal isolates were sensitive to both tebuconazole and prothioconazole; however, five isolates showed significantly reduced sensitivity to prothioconazole. The genome-wide association study identified one significant marker-trait association on chromosome 3 for tebuconazole resistance, whereas six significant marker-trait associations, one on chromosome 1, three on chromosome 2, and two on chromosome 4, were detected for prothioconazole resistance. Functional annotation of the marker-trait association for tebuconazole revealed a candidate gene encoding a basic helix-loop-helix domain-containing protein that reinforces sterol in the fungal membrane. Putative genes for prothioconazole resistance were also identified, which are involved in RNA interference, the detoxification by ubiquitin-proteasome pathway, and membrane integrity reinforcement. Considering the potential of the pathogen toward overcoming chemical control, continued monitoring of fungal sensitivities to commercially applied fungicides, especially those containing prothioconazole, is warranted to reduce risks of fungicide resistance in the pathogen populations.
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Affiliation(s)
- Bikash Poudel
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58102
| | - Joseph Mullins
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58102
| | - Jason D Fiedler
- Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, U.S. Department of Agriculture-Agricultural Research Service, Fargo, ND 58102
| | - Shaobin Zhong
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58102
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4
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Shoket H, Parvez S, Sharma M, Pandita M, Sharma V, Kumar P, Bairwa NK. Deletion of autophagy related, ATG1 and F-box motif encoding YDR131C, together, lead to synthetic growth defects and flocculation behavior in Saccharomyces cerevisiae. J Biochem Mol Toxicol 2022; 36:e23064. [PMID: 35385166 DOI: 10.1002/jbt.23064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 02/22/2022] [Accepted: 03/23/2022] [Indexed: 11/09/2022]
Abstract
Ubiquitin proteasome system (UPS) and autophagy both pathways are involved in clearing the nonessential cellular components and also crosstalk during cellular response to normal and stress conditions. The F-box motif proteins constitute the SCF-E3 ligase complex of the UPS pathway in Saccharomyces cerevisiae and are involved in the substrate recruitment for ubiquitination. The ATG1 encoded Atg1p, a conserved serine-threonine kinase is crucial for the autophagy process. Here in this study, we report that loss of F-box motif encoding YDR131C and ATG1 together results in growth defects, floc formation, sensitivity to hydroxyurea, methyl methanesulfonate, and hydrogen peroxide. Both the genes also interact with the flocculation-related genes (FLO) and associate with gene ontology terms "ubiquitin-protein transferase activity" and "cellular catabolic process." Based on in silico analysis and experimental evidence we conclude that YDR131C and ATG1 function in parallel pathways to regulate the growth, flocculation, and stress response.
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Affiliation(s)
- Heena Shoket
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Sadia Parvez
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Meenu Sharma
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Monika Pandita
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Vishali Sharma
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Prabhat Kumar
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Narendra K Bairwa
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
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5
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Shoket H, Pandita M, Sharma M, Kumar R, Rakwal A, Wazir S, Verma V, Salunke DB, Bairwa NK. Genetic interaction between F-box motif encoding YDR131C and retrograde signaling-related RTG1 regulates the stress response and apoptosis in Saccharomyces cerevisiae. J Biochem Mol Toxicol 2021; 35:e22864. [PMID: 34309121 DOI: 10.1002/jbt.22864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/18/2021] [Accepted: 07/16/2021] [Indexed: 12/22/2022]
Abstract
The retrograde signaling pathway is well conserved from yeast to humans, which regulates cell adaptation during stress conditions and prevents cell death. One of its components, RTG1 encoded Rtg1p in association with Rtg3p communicates between mitochondria, nucleus, and peroxisome during stress for adaptation, by regulation of transcription. The F-box motif protein encoded by YDR131C constitutes a part of SCF Ydr131c -E3 ligase complex, with unknown function; however, it is known that retrograde signaling is modulated by the E3 ligase complex. This study reports epistasis interaction between YDR131C and RTG1, which regulates cell growth, response to genotoxic stress, decreased apoptosis, resistance to petite mutation, and cell wall integrity. The cells of ydr131cΔrtg1Δ genetic background exhibits growth rate improvement however, sensitivity to hydroxyurea, itraconazole antifungal agent and synthetic indoloquinazoline-based alkaloid (8-fluorotryptanthrin, RK64), which disrupts the cell wall integrity in Saccharomyces cerevisiae. The epistatic interaction between YDR131C and RTG1 indicates a link between protein degradation and retrograde signaling pathways.
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Affiliation(s)
- Heena Shoket
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Monika Pandita
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Meenu Sharma
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Ravinder Kumar
- Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh, India
| | - Ayushi Rakwal
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Shreya Wazir
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Vijeshwar Verma
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Deepak B Salunke
- Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh, India.,National Interdisciplinary Centre of Vaccine, Immunotherapeutic and Antimicrobials, Panjab University, Chandigarh, India
| | - Narendra K Bairwa
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
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6
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Pandita M, Shoket H, Rakewal A, Wazir S, Kumar P, Kumar R, Bairwa NK. Genetic interaction between glyoxylate pathway regulator UCC1 and La-motif-encoding SRO9 regulates stress response and growth rate improvement in Saccharomyces cerevisiae. J Biochem Mol Toxicol 2021; 35:e22781. [PMID: 33797855 DOI: 10.1002/jbt.22781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/12/2021] [Accepted: 03/22/2021] [Indexed: 11/11/2022]
Abstract
Nonavailability of glucose as a carbon source results in glyoxylate pathway activation, which metabolizes nonfermentable carbon for energy generation in Saccharomyces cerevisiae. Ucc1p of S. cerevisiae inhibits activation of the glyoxylate pathway by targeting Cit2p, a key glyoxylate enzyme for ubiquitin-mediated proteasomal degradation when glucose is available as a carbon source. Sro9p, a La-motif protein involved in RNA biogenesis, interacts physically with the messenger RNA of UCC1; however, its functional relevance is yet to be discovered. This study presents binary epistatic interaction between UCC1 and SRO9, with functional implication on the growth rate, response to genotoxic stress, resistance to apoptosis, and petite mutation. Cells with ucc1Δsro9Δ, as their genetic background, exhibit alteration in morphology, improvement in growth rate, resistance to apoptosis, and petite mutation. Moreover, the study indicates a cross-link between ubiquitin-proteasome system and RNA biogenesis and metabolism, with applications in industrial fermentation and screening for cancer therapeutics.
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Affiliation(s)
- Monika Pandita
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Heena Shoket
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Aayushi Rakewal
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Shreya Wazir
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Prabhat Kumar
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Rakesh Kumar
- Cancer Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
| | - Narendra K Bairwa
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir, India
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7
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Lee JY, Hwang GW, Naganuma A, Satoh M. Methylmercury toxic mechanism related to protein degradation and chemokine transcription. Environ Health Prev Med 2020; 25:30. [PMID: 32680455 PMCID: PMC7469908 DOI: 10.1186/s12199-020-00868-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/29/2020] [Indexed: 01/01/2023] Open
Abstract
Methylmercury is an environmental pollutant that causes neurotoxicity. Recent studies have reported that the ubiquitin-proteasome system is involved in defense against methylmercury toxicity through the degradation of proteins synthesizing the pyruvate. Mitochondrial accumulation of pyruvate can enhance methylmercury toxicity. In addition, methylmercury exposure induces several immune-related chemokines, specifically in the brain, and may cause neurotoxicity. This summary highlights several molecular mechanisms of methylmercury-induced neurotoxicity.
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Affiliation(s)
- Jin-Yong Lee
- Laboratory of Pharmaceutical Health Sciences, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan.
| | - Gi-Wook Hwang
- Laboratory of Environmental and Health Sciences, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai, 981-8558, Japan.,Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Akira Naganuma
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Masahiko Satoh
- Laboratory of Pharmaceutical Health Sciences, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan
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8
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Lan Q, Wang Y, Sun Z, Li Y, Zhang C, Chang L, Gao Y, Wu J, Wang F, Xu P. Quantitative Proteomics Combined with Two Genetic Strategies for Screening Substrates of Ubiquitin Ligase Hrt3. J Proteome Res 2020; 19:493-502. [PMID: 31789040 DOI: 10.1021/acs.jproteome.9b00673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ubiquitin ligases (E3s) serve as key regulators for the ubiquitylation-mediated pathway. The identification of the corresponding relationship between E3 and its substrates is challenging but required for understanding the regulatory network of ubiquitylation. The low abundance of ubiquitinated conjugates and high redundancy of E3 substrate regulation made the screening pretty hard. Herein, we combined SILAC-based quantitative proteomics with two contrary genetic methods (overexpression and knockout) in theory for E3 (Hrt3, the F-box subunit of the SCF complex) substrate screening. The knockout method could not overcome the constraint mentioned above, while the overexpression approach turned on the access to the potential substrates of E3. Subsequently, we obtained 77 candidates, which are involved in many critical biological processes and need to be verified in the future. Within these candidates, we confirmed the relationship between one of the candidates Nce103 and Hrt3 and linked Hrt3 with oxygen sensitivity and oxidative stress response in which Nce103 took part as well. This research is also beneficial for understanding the impact of oxygen supply on regulation of yeast growth through the ubiquitination of Nce103.
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Affiliation(s)
- Qiuyan Lan
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Yihao Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China.,Department of Pharmacology and Toxicology , Beijing Institute of Radiation Medicine , Beijing 100850 , P. R. China
| | - Zhen Sun
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Yanchang Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Cheng Zhang
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China
| | - Lei Chang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Yue Gao
- Department of Pharmacology and Toxicology , Beijing Institute of Radiation Medicine , Beijing 100850 , P. R. China
| | - Junzhu Wu
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China
| | - Fuqiang Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Ping Xu
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China.,Second Clinical Medicine College , Guangzhou University Chinese Medicine , Guangzhou 510120 , P. R. China.,Research Unit of Proteomics & Research and Development of New Drug , Chinese Academy of Medical Sciences , Beijing 100730 , P. R. China
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9
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Yao M, Rahman SU, Wang A, Ma T, Raza SHA, Mehmood R, Liu Y, Tao S. Evolutionary Analysis of the F-Box Gene Family in Saccharomycetaceae. DNA Cell Biol 2019; 38:333-340. [PMID: 30801225 DOI: 10.1089/dna.2018.4271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
F-box proteins are a core component of Skp1-Cul1-F-box (SCF) ubiquitin/ligase complexes and are involved in a lot of cellular processes in yeasts. However, the current knowledge of the molecular evolution of the F-box gene family in yeasts remains unclear. In this study, 136 F-box genes were identified in 10 yeast species of the Saccharomycetaceae. In addition to the F-box domain, the other six domains were identified in these F-box proteins. The evolutionary history of F-box gene numbers in 10 Saccharomycetaceae yeasts was reconstructed. Whole-genome duplication, interspersed repeats, and gene loss events were inferred. These events contributed to F-box gene number variation in the 10 yeast species. Eighty-seven and 33 positively selected sites were detected in program Selecton and Datamonkey web-server, respectively. Three of them were considered the significant positively selected sites, and 23 of them had changed radically in amino acid properties by using TreeSAAP. We investigated F-box gene number variation and underlying mechanisms, and selection patterns, all of which were beneficial to deeply understand genome evolution and figure out the function of the F-box proteins.
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Affiliation(s)
- Mingyue Yao
- 1 College of Enology, Northwest A&F University, Yangling, China
| | - Siddiq Ur Rahman
- 2 State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, China
- 3 Bioinformatics Center, Northwest A&F University, Yangling, China
- 4 Department of Computer Science & Bioinformatics, Khushal Khan Khattak University, Karak, Pakistan
| | - Ailan Wang
- 2 State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, China
- 3 Bioinformatics Center, Northwest A&F University, Yangling, China
| | - Tao Ma
- 1 College of Enology, Northwest A&F University, Yangling, China
| | | | - Rashid Mehmood
- 6 Department of Computer Sciences and Information Technology, University of Kotli, Kotli, Pakistan
| | - Yanlin Liu
- 1 College of Enology, Northwest A&F University, Yangling, China
| | - Shiheng Tao
- 2 State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, China
- 3 Bioinformatics Center, Northwest A&F University, Yangling, China
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10
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Ke T, Gonçalves FM, Gonçalves CL, Dos Santos AA, Rocha JBT, Farina M, Skalny A, Tsatsakis A, Bowman AB, Aschner M. Post-translational modifications in MeHg-induced neurotoxicity. Biochim Biophys Acta Mol Basis Dis 2018; 1865:2068-2081. [PMID: 30385410 DOI: 10.1016/j.bbadis.2018.10.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/16/2018] [Accepted: 10/19/2018] [Indexed: 12/29/2022]
Abstract
Mercury (Hg) exposure remains a major public health concern due to its widespread distribution in the environment. Organic mercurials, such as MeHg, have been extensively investigated especially because of their congenital effects. In this context, studies on the molecular mechanism of MeHg-induced neurotoxicity are pivotal to the understanding of its toxic effects and the development of preventive measures. Post-translational modifications (PTMs) of proteins, such as phosphorylation, ubiquitination, and acetylation are essential for the proper function of proteins and play important roles in the regulation of cellular homeostasis. The rapid and transient nature of many PTMs allows efficient signal transduction in response to stress. This review summarizes the current knowledge of PTMs in MeHg-induced neurotoxicity, including the most commonly PTMs, as well as PTMs induced by oxidative stress and PTMs of antioxidant proteins. Though PTMs represent an important molecular mechanism for maintaining cellular homeostasis and are involved in the neurotoxic effects of MeHg, we are far from understanding the complete picture on their role, and further research is warranted to increase our knowledge of PTMs in MeHg-induced neurotoxicity.
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Affiliation(s)
- Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
| | - Filipe Marques Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Cinara Ludvig Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | | | - João B T Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105900 Santa Maria, RS, Brazil
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040900 Florianópolis, SC, Brazil
| | - Anatoly Skalny
- Yaroslavl State University, Sovetskaya St., 14, Yaroslavl 150000, Russia; Peoples' Friendship University of Russia (RUDN University), Miklukho-Maklaya St., 6, Moscow 105064, Russia; Orenburg State University, Pobedy Ave., 13, Orenburg 460352, Russia
| | - Aristidis Tsatsakis
- Center of Toxicology Science & Research, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN, United States.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
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11
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Guerra-Moreno A, Hanna J. Tmc1 Is a Dynamically Regulated Effector of the Rpn4 Proteotoxic Stress Response. J Biol Chem 2016; 291:14788-95. [PMID: 27226598 DOI: 10.1074/jbc.m116.726398] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Indexed: 11/06/2022] Open
Abstract
The ubiquitin-proteasome system represents the major pathway of selective intracellular protein degradation in eukaryotes. Misfolded proteins represent an important class of substrates for this pathway, and the failure to destroy misfolded proteins is associated with a number of human diseases. The transcription factor Rpn4 mediates a key proteotoxic stress response whose best known function is to control proteasome abundance by a homeostatic feedback mechanism. Here we identify the uncharacterized zinc finger protein Tmc1 as a dynamically regulated stress-responsive protein. Rpn4 induces TMC1 transcription in response to misfolded proteins. However, this response is counteracted by rapid proteasome-dependent degradation of Tmc1, which serves to normalize Tmc1 protein levels after induction. Precise control of Tmc1 levels is needed in vivo to survive multiple stressors related to proteostasis. Thus, Tmc1 represents a novel effector and substrate of the Rpn4 proteotoxic stress response.
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Affiliation(s)
- Angel Guerra-Moreno
- From the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
| | - John Hanna
- From the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
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Whi2 enhances methylmercury toxicity in yeast via inhibition of Akr1 palmitoyltransferase activity. Biochim Biophys Acta Gen Subj 2016; 1860:1326-33. [PMID: 27015763 DOI: 10.1016/j.bbagen.2016.03.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/20/2016] [Accepted: 03/20/2016] [Indexed: 11/23/2022]
Abstract
BACKGROUND We have previously reported that Whi2 enhances the toxicity of methylmercury in yeast. In the present study we examined the proteins known to interact with Whi2 to find those that influence the toxicity of methylmercury. METHODS Gene disruption and site-directed mutagenesis were employed to examine the relationship of mercury toxicity and palmitoylation. Protein palmitoylation was examined using the acyl-biotinyl exchange method. Protein-protein interactions were detected by immunoprecipitation and immunoblotting. RESULTS We found that deletion of Akr1, a palmitoyltransferase, rendered yeast cells highly sensitive to methylmercury, and Akr1 is necessary for the methylmercury resistance of Whi2-deleted yeast. Palmitoyltransferase activity of Akr1 has an important role in the alleviation of methylmercury toxicity. Whi2 deletion or methylmercury treatment enhanced the palmitoyltransferase activity of Akr1, and methylmercury treatment reduced the binding between Akr1 and Whi2. CONCLUSIONS Whi2 bonds to Akr1 (a protein that is able to alleviate methylmercury toxicity) and thus inhibits Akr1's palmitoyltransferase activity, which leads to enhanced methylmercury toxicity. In contrast, methylmercury might break the bond between Whi2 and Akr1, which enhances the palmitoyltransferase activity of Akr1 to alleviate methylmercury toxicity. GENERAL SIGNIFICANCE This study's findings propose that the Whi2/Akr1 system can be regarded as a defense mechanism that detects methylmercury incorporation of yeast cells and alleviates its toxicity.
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Transport of pyruvate into mitochondria is involved in methylmercury toxicity. Sci Rep 2016; 6:21528. [PMID: 26899208 PMCID: PMC4761912 DOI: 10.1038/srep21528] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 01/26/2016] [Indexed: 01/24/2023] Open
Abstract
We have previously demonstrated that the overexpression of enzymes involved in the production of pyruvate, enolase 2 (Eno2) and D-lactate dehydrogenase (Dld3) renders yeast highly sensitive to methylmercury and that the promotion of intracellular pyruvate synthesis may be involved in intensifying the toxicity of methylmercury. In the present study, we showed that the addition of pyruvate to culture media in non-toxic concentrations significantly enhanced the sensitivity of yeast and human neuroblastoma cells to methylmercury. The results also suggested that methylmercury promoted the transport of pyruvate into mitochondria and that the increased pyruvate concentrations in mitochondria were involved in intensifying the toxicity of methylmercury without pyruvate being converted to acetyl-CoA. Furthermore, in human neuroblastoma cells, methylmercury treatment alone decreased the mitochondrial membrane potential, and the addition of pyruvate led to a further significant decrease. In addition, treatment with N-acetylcysteine (an antioxidant) significantly alleviated the toxicity of methylmercury and significantly inhibited the intensification of methylmercury toxicity by pyruvate. Based on these data, we hypothesize that methylmercury exerts its toxicity by raising the level of pyruvate in mitochondria and that mitochondrial dysfunction and increased levels of reactive oxygen species are involved in the action of pyruvate.
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Lee JY, Ishida Y, Kuge S, Naganuma A, Hwang GW. Identification of substrates of F-box protein involved in methylmercury toxicity in yeast cells. FEBS Lett 2015; 589:2720-5. [PMID: 26297823 DOI: 10.1016/j.febslet.2015.08.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/04/2015] [Accepted: 08/06/2015] [Indexed: 12/31/2022]
Abstract
We previously reported that some of the substrate proteins recognized by Hrt3 or Ucc1, a component of Skp1/Cdc53/F-box protein ubiquitin ligase, may include proteins that are involved in the methylmercury toxicity and degraded by the proteasome. In this study, we found that Dld3 and Grs1 bound to Hrt3 and that Eno2 bound to Ucc1 using a yeast two-hybrid screening. We demonstrated that Dld3 and Grs1 are substrates that are ubiquitinated by Hrt3, and Eno2 is a substrate that is ubiquitinated by Ucc1. Moreover, any yeast showing overexpression of Dld3, Grs1, and Eno2 demonstrated higher methylmercury sensitivity. This indicates that Hrt3 and Ucc1 are involved in alleviating the methylmercury toxicity by promoting proteasomal degradation through the ubiquitination of Dld3, Grs1, and Eno2.
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Affiliation(s)
- Jin-Yong Lee
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan; Laboratory of Pharmaceutical Health Sciences, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan
| | - Yosuke Ishida
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Shusuke Kuge
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan; Department of Microbiology, Tohoku Pharmaceutical University, Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Akira Naganuma
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
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Hwang GW, Murai Y, Takahashi T, Naganuma A. The protein transportation pathway from Golgi to vacuoles via endosomes plays a role in enhancement of methylmercury toxicity. Sci Rep 2014; 4:5888. [PMID: 25074250 PMCID: PMC4118254 DOI: 10.1038/srep05888] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/14/2014] [Indexed: 11/09/2022] Open
Abstract
Methylmercury causes serious damage to the central nervous system, but the molecular mechanisms of methylmercury toxicity are only marginally understood. In this study, we used a gene-deletion mutant library of budding yeast to conduct genome-wide screening for gene knockouts affecting the sensitivity of methylmercury toxicity. We successfully identified 31 genes whose deletions confer resistance to methylmercury in yeast, and 18 genes whose deletions confer hypersensitivity to methylmercury. Yeast genes whose deletions conferred resistance to methylmercury included many gene encoding factors involved in protein transport to vacuoles. Detailed examination of the relationship between the factors involved in this transport system and methylmercury toxicity revealed that mutants with loss of the factors involved in the transportation pathway from the trans-Golgi network (TGN) to the endosome, protein uptake into the endosome, and endosome-vacuole fusion showed higher methylmercury resistance than did wild-type yeast. The results of our genetic engineering study suggest that this vesicle transport system (proteins moving from the TGN to vacuole via endosome) is responsible for enhancing methylmercury toxicity due to the interrelationship between the pathways. There is a possibility that there may be proteins in the cell that enhance methylmercury toxicity through the protein transport system.
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Affiliation(s)
- Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Yasutaka Murai
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Tsutomu Takahashi
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Akira Naganuma
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
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Hanna J, Waterman D, Isasa M, Elsasser S, Shi Y, Gygi S, Finley D. Cuz1/Ynl155w, a zinc-dependent ubiquitin-binding protein, protects cells from metalloid-induced proteotoxicity. J Biol Chem 2013; 289:1876-85. [PMID: 24297164 DOI: 10.1074/jbc.m113.534032] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein misfolding is a universal threat to cells. The ubiquitin-proteasome system mediates a cellular stress response capable of eliminating misfolded proteins. Here we identify Cuz1/Ynl155w as a component of the ubiquitin system, capable of interacting with both the proteasome and Cdc48. Cuz1/Ynl155w is regulated by the transcription factor Rpn4, and is required for cells to survive exposure to the trivalent metalloids arsenic and antimony. A related protein, Yor052c, shows similar phenotypes, suggesting a multicomponent stress response pathway. Cuz1/Ynl155w functions as a zinc-dependent ubiquitin-binding protein. Thus, Cuz1/Ynl155w is proposed to protect cells from metalloid-induced proteotoxicity by delivering ubiquitinated substrates to Cdc48 and the proteasome for destruction.
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Affiliation(s)
- John Hanna
- From the Department of Pathology, Brigham and Women's Hospital, and
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Hwang GW, Mastuyama F, Takahashi T, Lee JY, Naganuma A. Deletion of the ubiquitin-conjugating enzyme Ubc2 confers resistance to methylmercury in budding yeast by promoting Whi2 degradation. J Toxicol Sci 2013; 38:301-3. [PMID: 23535409 DOI: 10.2131/jts.38.301] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ubiquitin-conjugating enzymes involved in sensitivity to methylmercury in yeast were identified by deletion analysis, which showed that Ubc2- or Ubp13-deficiency conferred resistance to methylmercury. Whi2, which was previously shown to be associated with increased methylmercury toxicity and is intracellularly degraded via the ubiquitin-proteasome system, was expressed at significantly lower levels in Ubc2-deficient yeast than in wild-type yeast. Ubc2/Whi2 double-deficient yeast showed neither an additive nor synergistic increase in methylmercury resistance. Our results indicate that Ubc2 may increase the sensitivity to methylmercury in yeast by inhibiting the proteasomal degradation of Whi2.
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Affiliation(s)
- Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
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18
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Hwang GW, Kimura Y, Takahashi T, Lee JY, Naganuma A. Identification of deubiquitinating enzymes involved in methylmercury toxicity in Saccharomyces cerevisiae. J Toxicol Sci 2013. [PMID: 23208446 DOI: 10.2131/jts.37.1287] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Deubiquitinating enzymes that influence the methylmercury susceptibility of yeast cells were investigated. Deficiency of Ubp2, Ubp4, Ubp 6, or Ubp14 conferred methylmercury resistance on cells, while deficiency of Ubp7, Ubp13, or Ubp15 conferred high methylmercury susceptibility. Of these enzymes, deficiency of Ubp4 and Ubp6 was associated with particularly high methylmercury resistance. Yeast cells treated with a proteasome inhibitor showed methylmercury resistance due to Ubp4 deficiency, but not due to Ubp6 deficiency. Thus, the enhanced methylmercury toxicity associated with Ubp6 expression requires proteasomal activity, suggesting that Ubp4 and Ubp6 contribute to enhanced methylmercury toxicity through different mechanisms.
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Affiliation(s)
- Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Miyagi, Japan
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González-Ramos D, van den Broek M, van Maris AJA, Pronk JT, Daran JMG. Genome-scale analyses of butanol tolerance in Saccharomyces cerevisiae reveal an essential role of protein degradation. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:48. [PMID: 23552365 PMCID: PMC3621596 DOI: 10.1186/1754-6834-6-48] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/22/2013] [Indexed: 05/04/2023]
Abstract
BACKGROUND n-Butanol and isobutanol produced from biomass-derived sugars are promising renewable transport fuels and solvents. Saccharomyces cerevisiae has been engineered for butanol production, but its high butanol sensitivity poses an upper limit to product titers that can be reached by further pathway engineering. A better understanding of the molecular basis of butanol stress and tolerance of S. cerevisiae is important for achieving improved tolerance. RESULTS By combining a screening of the haploid S. cerevisiae knock-out library, gene overexpression, and genome analysis of evolutionary engineered n-butanol-tolerant strains, we established that protein degradation plays an essential role in tolerance. Strains deleted in genes involved in the ubiquitin-proteasome system and in vacuolar degradation of damaged proteins showed hypersensitivity to n-butanol. Overexpression of YLR224W, encoding the subunit responsible for the recognition of damaged proteins of an ubiquitin ligase complex, resulted in a strain with a higher n-butanol tolerance. Two independently evolved n-butanol-tolerant strains carried different mutations in both RPN4 and RTG1, which encode transcription factors involved in the expression of proteasome and peroxisomal genes, respectively. Introduction of these mutated alleles in the reference strain increased butanol tolerance, confirming their relevance in the higher tolerance phenotype. The evolved strains, in addition to n-butanol, were also more tolerant to 2-butanol, isobutanol and 1-propanol, indicating a common molecular basis for sensitivity and tolerance to C3 and C4 alcohols. CONCLUSIONS This study shows that maintenance of protein integrity plays an essential role in butanol tolerance and demonstrates new promising targets to engineer S. cerevisiae for improved tolerance.
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Affiliation(s)
- Daniel González-Ramos
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, P.O. Box 5057, Delft 2600 GA, The Netherlands
| | - Marcel van den Broek
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, P.O. Box 5057, Delft 2600 GA, The Netherlands
| | - Antonius JA van Maris
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, P.O. Box 5057, Delft 2600 GA, The Netherlands
| | - Jack T Pronk
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, P.O. Box 5057, Delft 2600 GA, The Netherlands
- Platform for Green Synthetic Biology, P.O. Box 5057, Delft 2600 GA, The Netherlands
| | - Jean-Marc G Daran
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, P.O. Box 5057, Delft 2600 GA, The Netherlands
- Platform for Green Synthetic Biology, P.O. Box 5057, Delft 2600 GA, The Netherlands
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Hwang GW. Role of the Ubiquitin-proteasome System in Methylmercury Toxicity in Saccharomyces cerevisiae. ACTA ACUST UNITED AC 2011. [DOI: 10.1248/jhs.57.129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate of Pharmaceutical Sciences, Tohoku University
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Hwang GW, Wada N, Kuge S, Naganuma A. Overexpression of the novel F-box protein Ymr258c confers resistance to methylmercury in Saccharomyces cerevisiae. J Toxicol Sci 2009; 34:413-6. [PMID: 19652464 DOI: 10.2131/jts.34.413] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We searched a yeast genomic library for genes that conferred methylmercury resistance to yeast. Ymr258c was identified as a factor that conferred strong methylmercury resistance when overexpressed in budding yeast. Ymr258c is regarded as one of the F-box proteins, i.e., component factors of the Skp1/Cullin/F-box protein (SCF) complex that functions as a ubiquitin ligase in the ubiquitin-proteasome system. In this study, Ymr258c was demonstrated to function as an F-box protein to reduce methylmercury toxicity. The overexpression of Ymr258c might promote the ubiquitination of proteins that are involved in the enhancement of methylmercury toxicity, and thereby promote their degradation by proteasomes to reduce methylmercury toxicity.
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Yang YK, Ko SK, Shin I, Tae J. Fluorescent detection of methylmercury by desulfurization reaction of rhodamine hydrazide derivatives. Org Biomol Chem 2009; 7:4590-3. [DOI: 10.1039/b915723a] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Localizing organomercury uptake and accumulation in zebrafish larvae at the tissue and cellular level. Proc Natl Acad Sci U S A 2008; 105:12108-12. [PMID: 18719123 DOI: 10.1073/pnas.0803147105] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Using synchrotron x-ray fluorescence mapping, we have examined the uptake and localization of organic mercury in zebrafish larvae. Strikingly, the greatest accumulation of methyl and ethyl mercury compounds was highly localized in the rapidly dividing lens epithelium, with lower levels going to brain, optic nerve, and various other organs. The data suggest that the reported impairment of visual processes by mercury may arise not only from previously reported neurological effects, but also from direct effects on the ocular tissue. This novel approach is a powerful tool for directly investigating the molecular toxicology of heavy metals, and should be equally applicable to the study of a wide range of elements in developing embryos.
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Hwang GW. A Ubiquitin-proteasome System as a Factor that Determine the Sensitivity to Methylmercury. YAKUGAKU ZASSHI 2007; 127:463-8. [PMID: 17329932 DOI: 10.1248/yakushi.127.463] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To elucidate the mechanism of toxicity of methylmercury (MeHg), we searched for factors that determine the sensitivity of yeast cells to MeHg and found that overexpression of Cdc34 or Rad23, both proteins related to the ubiquitin-proteasome (UP) system, induces resistance to MeHg toxicity. The acquisition of resistance to MeHg in Cdc34-overexpressing yeast cells requires the ubiquitin-conjugating activity of Cdc34 and the proteolytic activity of proteasomes. Therefore, it seems likely that certain as-yet-unidentified proteins that increase MeHg toxicity might exist in cells and that the toxicity of MeHg might be reduced by the enhanced degradation of such proteins through the UP system when Cdc34 is overexpressed. Unlike Cdc34, Rad23 suppresses the degradation of ubiquitinated proteins by proteasomes. This activity of Rad23 might be involved in the acquisition of resistance to MeHg toxicity when Rad23 is overexpressed. Overexpression of Rad23 might induce resistance to MeHg by suppressing the degradation of proteins that reduce the MeHg toxicity. Moreover, when we overexpressed Cdc34 in normal and Rad23-defective yeasts, resistance to MeHg was enhanced to almost the same extent in both lines of yeast cells. Thus it is possible that the binding of Rad23 to ubiquitinated proteins might be regulated by a mechanism that involves the recognition of substrate proteins and that the functions of Rad23 might not affect the protein-degradation system in which Cdc34 is involved. Many proteins that reduce or enhance MeHg toxicity and are ubiquitinated might exist in cells. The UP system and related proteins might determine the extent of MeHg toxicity by regulating the cellular concentrations of these various proteins.
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Affiliation(s)
- Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
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Current awareness on yeast. Yeast 2007. [DOI: 10.1002/yea.1329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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