1
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Bommisetti P, Bandarian V. Insights into the Mechanism of Installation of 5-Carboxymethylaminomethyl Uridine Hypermodification by tRNA-Modifying Enzymes MnmE and MnmG. J Am Chem Soc 2023; 145:26947-26961. [PMID: 38050996 PMCID: PMC10723064 DOI: 10.1021/jacs.3c10182] [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: 09/15/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/07/2023]
Abstract
The evolutionarily conserved bacterial proteins MnmE and MnmG (and their homologues in Eukarya) install a 5-carboxymethylaminomethyl (cmnm5) or a 5-taurinomethyl (τm5) group onto wobble uridines of several tRNA species. The Escherichia coli MnmE binds guanosine-5'-triphosphate (GTP) and methylenetetrahydrofolate (CH2THF), while MnmG binds flavin adenine dinucleotide (FAD) and a reduced nicotinamide adenine dinucleotide (NADH). Together with glycine, MnmEG catalyzes the installation of cmnm5 in a reaction that also requires hydrolysis of GTP. In this letter, we investigated key steps of the MnmEG reaction using a combination of biochemical techniques. We show multiple lines of evidence supporting flavin-iminium FADH[N5═CH2]+ as a central intermediate in the MnmEG reaction. Using a synthetic FADH[N5═CD2]+ analogue, the intermediacy of the FAD in the transfer of the methylene group from CH2THF to the C5 position of U34 was unambiguously demonstrated. Further, MnmEG reactions containing the deuterated flavin-iminium intermediate and alternate nucleophiles such as taurine and ammonia also led to the formation of the anticipated U34-modified tRNAs, showing FAD[N5═CH2]+ as the universal intermediate for all MnmEG homologues. Additionally, an RNA-protein complex stable to urea-denaturing polyacrylamide gel electrophoresis was identified. Studies involving a series of nuclease (RNase T1) and protease (trypsin) digestions along with reverse transcription experiments suggest that the complex may be noncovalent. While the conserved MnmG cysteine C47 and C277 mutant variants were shown to reduce FAD, they were unable to promote the modified tRNA formation. Overall, this study provides critical insights into the biochemical mechanism underlying tRNA modification by the MnmEG.
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Affiliation(s)
- Praneeth Bommisetti
- Department of Chemistry, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Vahe Bandarian
- Department of Chemistry, University of Utah, Salt Lake
City, Utah 84112, United States
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2
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Lyu Z, Wilson C, Ling J. Translational Fidelity during Bacterial Stresses and Host Interactions. Pathogens 2023; 12:383. [PMID: 36986305 PMCID: PMC10057733 DOI: 10.3390/pathogens12030383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
Translational fidelity refers to accuracy during protein synthesis and is maintained in all three domains of life. Translational errors occur at base levels during normal conditions and may rise due to mutations or stress conditions. In this article, we review our current understanding of how translational fidelity is perturbed by various environmental stresses that bacterial pathogens encounter during host interactions. We discuss how oxidative stress, metabolic stresses, and antibiotics affect various types of translational errors and the resulting effects on stress adaption and fitness. We also discuss the roles of translational fidelity during pathogen-host interactions and the underlying mechanisms. Many of the studies covered in this review will be based on work with Salmonella enterica and Escherichia coli, but other bacterial pathogens will also be discussed.
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Affiliation(s)
| | | | - Jiqiang Ling
- Department of Cell Biology and Molecular Genetics, The University of Maryland, College Park, MD 20742, USA
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3
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Abstract
Atlastin (ATL) GTPases undergo trans dimerization and a power strokelike crossover conformational rearrangement to drive endoplasmic reticulum membrane fusion. Fusion depends on GTP, but the role of nucleotide hydrolysis has remained controversial. For instance, nonhydrolyzable GTP analogs block fusion altogether, suggesting a requirement for GTP hydrolysis in ATL dimerization and crossover, but this leaves unanswered the question of how the ATL dimer is disassembled after fusion. We recently used the truncated cytoplasmic domain of wild-type Drosophila ATL (DATL) and a novel hydrolysis-deficient D127N variant in single turnover assays to reveal that dimerization and crossover consistently precede GTP hydrolysis, with hydrolysis coinciding more closely with dimer disassembly. Moreover, while nonhydrolyzable analogs can bind the DATL G domain, they fail to fully recapitulate the GTP-bound state. This predicted that nucleotide hydrolysis would be dispensable for fusion. Here we report that the D127N variant of full-length DATL drives both outer and inner leaflet membrane fusion with little to no detectable hydrolysis of GTP. However, the trans dimer fails to disassemble and subsequent rounds of fusion fail to occur. Our findings confirm that ATL mediated fusion is driven in the GTP-bound state, with nucleotide hydrolysis serving to reset the fusion machinery for recycling.
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Affiliation(s)
- Daniel Crosby
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Tina H. Lee
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213,*Address correspondence to: Tina H. Lee ()
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4
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Bommisetti P, Young A, Bandarian V. Elucidation of the substrate of tRNA-modifying enzymes MnmEG leads to in vitro reconstitution of an evolutionarily conserved uridine hypermodification. J Biol Chem 2022; 298:102548. [PMID: 36181794 PMCID: PMC9626948 DOI: 10.1016/j.jbc.2022.102548] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 12/02/2022] Open
Abstract
The evolutionarily conserved bacterial proteins MnmE and MnmG collectively install a carboxymethylaminomethyl (cmnm) group at the fifth position of wobble uridines of several tRNA species. While the reaction catalyzed by MnmEG is one of the central steps in the biosynthesis of the methylaminomethyl (mnm) posttranscriptional tRNA modification, details of the reaction remain elusive. Glycine is known to be the source of the carboxy methylamino moiety of cmnm, and a tetrahydrofolate (THF) analog is thought to supply the one carbon that is appended to the fifth position of U. However, the nature of the folate analog remains unknown. This article reports the in vitro biochemical reconstitution of the MnmEG reaction. Using isotopically labeled methyl and methylene THF analogs, we demonstrate that methylene THF is the true substrate. We also show that reduced FAD is required for the reaction and that DTT can replace the NADH in its role as a reductant. We discuss the implications of these methylene-THF and reductant requirements on the mechanism of this key tRNA modification catalyzed by MnmEG.
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Affiliation(s)
- Praneeth Bommisetti
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Anthony Young
- Soliome Inc, 479 Jessie Street, San Francisco, CA 94103, United States
| | - Vahe Bandarian
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States.
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5
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Peng GX, Zhang Y, Wang QQ, Li QR, Xu H, Wang ED, Zhou XL. The human tRNA taurine modification enzyme GTPBP3 is an active GTPase linked to mitochondrial diseases. Nucleic Acids Res 2021; 49:2816-2834. [PMID: 33619562 PMCID: PMC7969015 DOI: 10.1093/nar/gkab104] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/03/2021] [Accepted: 02/09/2021] [Indexed: 01/03/2023] Open
Abstract
GTPBP3 and MTO1 cooperatively catalyze 5-taurinomethyluridine (τm5U) biosynthesis at the 34th wobble position of mitochondrial tRNAs. Mutations in tRNAs, GTPBP3 or MTO1, causing τm5U hypomodification, lead to various diseases. However, efficient in vitro reconstitution and mechanistic study of τm5U modification have been challenging, in part due to the lack of pure and active enzymes. A previous study reported that purified human GTPBP3 (hGTPBP3) is inactive in GTP hydrolysis. Here, we identified the mature form of hGTPBP3 and showed that hGTPBP3 is an active GTPase in vitro that is critical for tRNA modification in vivo. Unexpectedly, the isolated G domain and a mutant with the N-terminal domain truncated catalyzed GTP hydrolysis to only a limited extent, exhibiting high Km values compared with that of the mature enzyme. We further described several important pathogenic mutations of hGTPBP3, associated with alterations in hGTPBP3 localization, structure and/or function in vitro and in vivo. Moreover, we discovered a novel cytoplasm-localized isoform of hGTPBP3, indicating an unknown potential noncanonical function of hGTPBP3. Together, our findings established, for the first time, the GTP hydrolysis mechanism of hGTPBP3 and laid a solid foundation for clarifying the τm5U modification mechanism and etiology of τm5U deficiency-related diseases.
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Affiliation(s)
- Gui-Xin Peng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.,School of Life Science and Technology, ShanghaiTech University, 393 Middle Hua Xia Road, Shanghai 201210, China
| | - Yong Zhang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Qin-Qin Wang
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Hua Xia Road, Shanghai 201210, China
| | - Qing-Run Li
- CAS Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Hong Xu
- Shanghai Key Laboratory of Embryo Original Diseases, Shanghai Municipal Key Clinical Specialty, the International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, 910 Heng Shan Road, Shanghai 200030, China
| | - En-Duo Wang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.,School of Life Science and Technology, ShanghaiTech University, 393 Middle Hua Xia Road, Shanghai 201210, China
| | - Xiao-Long Zhou
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
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6
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Asano K, Suzuki T, Saito A, Wei FY, Ikeuchi Y, Numata T, Tanaka R, Yamane Y, Yamamoto T, Goto T, Kishita Y, Murayama K, Ohtake A, Okazaki Y, Tomizawa K, Sakaguchi Y, Suzuki T. Metabolic and chemical regulation of tRNA modification associated with taurine deficiency and human disease. Nucleic Acids Res 2019; 46:1565-1583. [PMID: 29390138 PMCID: PMC5829720 DOI: 10.1093/nar/gky068] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 01/23/2018] [Indexed: 12/21/2022] Open
Abstract
Modified uridine containing taurine, 5-taurinomethyluridine (τm5U), is found at the anticodon first position of mitochondrial (mt-)transfer RNAs (tRNAs). Previously, we reported that τm5U is absent in mt-tRNAs with pathogenic mutations associated with mitochondrial diseases. However, biogenesis and physiological role of τm5U remained elusive. Here, we elucidated τm5U biogenesis by confirming that 5,10-methylene-tetrahydrofolate and taurine are metabolic substrates for τm5U formation catalyzed by MTO1 and GTPBP3. GTPBP3-knockout cells exhibited respiratory defects and reduced mitochondrial translation. Very little τm5U34 was detected in patient's cells with the GTPBP3 mutation, demonstrating that lack of τm5U results in pathological consequences. Taurine starvation resulted in downregulation of τm5U frequency in cultured cells and animal tissues (cat liver and flatfish). Strikingly, 5-carboxymethylaminomethyluridine (cmnm5U), in which the taurine moiety of τm5U is replaced with glycine, was detected in mt-tRNAs from taurine-depleted cells. These results indicate that tRNA modifications are dynamically regulated via sensing of intracellular metabolites under physiological condition.
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Affiliation(s)
- Kana Asano
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Ayaka Saito
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Yoshiho Ikeuchi
- Institute of Industrial Science, University of Tokyo, Meguro-ku, Tokyo 153-8505, Japan
| | - Tomoyuki Numata
- Biological Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan
| | - Ryou Tanaka
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Animal Medical Center, Fuchu, Tokyo 183-8509, Japan
| | - Yoshihisa Yamane
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Animal Medical Center, Fuchu, Tokyo 183-8509, Japan
| | - Takeshi Yamamoto
- Tamaki Laboratory, National Research Institute of Aquaculture, Japan Fisheries Research and Education Agency, Tamaki, Mie 519-0423, Japan
| | - Takanobu Goto
- Department of Chemistry & Biochemistry, National Institute of Technology, Numazu College, Numazu, Shizuoka 410-8501, Japan
| | - Yoshihito Kishita
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Saitama 350-1240, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Midori-ku, Chiba 266-0007, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan
| | - Yasushi Okazaki
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Saitama 350-1240, Japan.,Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Saitama 350-1240, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Yuriko Sakaguchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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7
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Wauters L, Terheyden S, Gilsbach BK, Leemans M, Athanasopoulos PS, Guaitoli G, Wittinghofer A, Gloeckner CJ, Versées W, Kortholt A. Biochemical and kinetic properties of the complex Roco G-protein cycle. Biol Chem 2019; 399:1447-1456. [PMID: 30067506 DOI: 10.1515/hsz-2018-0227] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 07/23/2018] [Indexed: 12/12/2022]
Abstract
Roco proteins have come into focus after mutations in the gene coding for the human Roco protein Leucine-rich repeat kinase 2 (LRRK2) were discovered to be one of the most common genetic causes of late onset Parkinson's disease. Roco proteins are characterized by a Roc domain responsible for GTP binding and hydrolysis, followed by a COR dimerization device. The regulation and function of this RocCOR domain tandem is still not completely understood. To fully biochemically characterize Roco proteins, we performed a systematic survey of the kinetic properties of several Roco protein family members, including LRRK2. Together, our results show that Roco proteins have a unique G-protein cycle. Our results confirm that Roco proteins have a low nucleotide affinity in the micromolar range and thus do not strictly depend on G-nucleotide exchange factors. Measurement of multiple and single turnover reactions shows that neither Pi nor GDP release are rate-limiting, while this is the case for the GAP-mediated GTPase reaction of some small G-proteins like Ras and for most other high affinity Ras-like proteins, respectively. The KM values of the reactions are in the range of the physiological GTP concentration, suggesting that LRRK2 functioning might be regulated by the cellular GTP level.
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Affiliation(s)
- Lina Wauters
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.,Department of Cell Biochemistry, University of Groningen, Groningen NL-9747 AG, The Netherlands.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Susanne Terheyden
- Department of Cell Biochemistry, University of Groningen, Groningen NL-9747 AG, The Netherlands.,Structural Biology Group, Max-Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Bernd K Gilsbach
- German Center for Neurodegenerative Diseases (DZNE), Otfried-Müller-Str. 23, D-72076 Tübingen, Germany
| | - Margaux Leemans
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | | | - Giambattista Guaitoli
- German Center for Neurodegenerative Diseases (DZNE), Otfried-Müller-Str. 23, D-72076 Tübingen, Germany
| | - Alfred Wittinghofer
- Structural Biology Group, Max-Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Christian Johannes Gloeckner
- German Center for Neurodegenerative Diseases (DZNE), Otfried-Müller-Str. 23, D-72076 Tübingen, Germany.,University of Tübingen, Institute for Ophthalmic Research, Center for Ophthalmology, D-72076 Tübingen, Germany
| | - Wim Versées
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Groningen NL-9747 AG, The Netherlands
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8
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Wauters L, Versées W, Kortholt A. Roco Proteins: GTPases with a Baroque Structure and Mechanism. Int J Mol Sci 2019; 20:ijms20010147. [PMID: 30609797 PMCID: PMC6337361 DOI: 10.3390/ijms20010147] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/21/2018] [Accepted: 12/25/2018] [Indexed: 01/05/2023] Open
Abstract
Mutations in leucine-rich repeat kinase 2 (LRRK2) are a common cause of genetically inherited Parkinson’s Disease (PD). LRRK2 is a large, multi-domain protein belonging to the Roco protein family, a family of GTPases characterized by a central RocCOR (Ras of complex proteins/C-terminal of Roc) domain tandem. Despite the progress in characterizing the GTPase function of Roco proteins, there is still an ongoing debate concerning the working mechanism of Roco proteins in general, and LRRK2 in particular. This review consists of two parts. First, an overview is given of the wide evolutionary range of Roco proteins, leading to a variety of physiological functions. The second part focusses on the GTPase function of the RocCOR domain tandem central to the action of all Roco proteins, and progress in the understanding of its structure and biochemistry is discussed and reviewed. Finally, based on the recent work of our and other labs, a new working hypothesis for the mechanism of Roco proteins is proposed.
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Affiliation(s)
- Lina Wauters
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.
- Department of Cell Biochemistry, University of Groningen, NL-9747 AG Groningen, The Netherlands.
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
| | - Wim Versées
- VIB-VUB Center for Structural Biology, Pleinlaan 2, B-1050 Brussels, Belgium.
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, NL-9747 AG Groningen, The Netherlands.
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9
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Ruiz-Partida R, Prado S, Villarroya M, Velázquez-Campoy A, Bravo J, Armengod ME. An Alternative Homodimerization Interface of MnmG Reveals a Conformational Dynamics that Is Essential for Its tRNA Modification Function. J Mol Biol 2018; 430:2822-2842. [PMID: 29870725 DOI: 10.1016/j.jmb.2018.05.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 05/25/2018] [Indexed: 01/28/2023]
Abstract
The Escherichia coli homodimeric proteins MnmE and MnmG form a functional complex, MnmEG, that modifies tRNAs using GTP, methylene-tetrahydrofolate, FAD, and glycine or ammonium. MnmE is a tetrahydrofolate- and GTP-binding protein, whereas MnmG is a FAD-binding protein with each protomer composed of the FAD-binding domain, two insertion domains, and the helical C-terminal domain. The detailed mechanism of the MnmEG-mediated reaction remains unclear partially due to incomplete structural information on the free- and substrate-bound forms of the complex. In this study, we show that MnmG can adopt in solution a dimer arrangement (form I) different from that currently considered as the only biologically active (form II). Normal mode analysis indicates that form I can oscillate in a range of open and closed conformations. Using isothermal titration calorimetry and native red electrophoresis, we show that a form-I open conformation, which can be stabilized in vitro by the formation of an interprotomer disulfide bond between the catalytic C277 residues, appears to be involved in the assembly of the MnmEG catalytic center. We also show that residues R196, D253, R436, R554 and E585 are important for the stabilization of form I and the tRNA modification function. We propose that the form I dynamics regulates the alternative access of MnmE and tRNA to the MnmG FAD active site. Finally, we show that the C-terminal region of MnmG contains a sterile alpha motif domain responsible for tRNA-protein and protein-protein interactions.
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Affiliation(s)
| | - Silvia Prado
- Centro de Investigación Príncipe Felipe, Valencia 46012, Spain
| | | | - Adrián Velázquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, and Department of Biochemistry and Molecular and Cell Biology, Universidad de Zaragoza, Zaragoza 50018, Spain; Aragon Institute for Health Research (IIS Aragon), Zaragoza, 50009, Spain; Biomedical Research Networking Centre for Liver and Digestive Diseases (CIBERehd), Madrid 28029, Spain; Fundacion ARAID, Government of Aragon, Zaragoza 50018, Spain
| | - Jerónimo Bravo
- Instituto de Biomedicina de Valencia-CSIC, Valencia 46010, Spain
| | - M-Eugenia Armengod
- Centro de Investigación Príncipe Felipe, Valencia 46012, Spain; Biomedical Research Networking Centre for Rare Diseases (CIBERER, Node 721), Valencia, Spain.
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10
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11
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Gkekas S, Singh RK, Shkumatov AV, Messens J, Fauvart M, Verstraeten N, Michiels J, Versées W. Structural and biochemical analysis of Escherichia coli ObgE, a central regulator of bacterial persistence. J Biol Chem 2017; 292:5871-5883. [PMID: 28223358 DOI: 10.1074/jbc.m116.761809] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 02/03/2017] [Indexed: 12/28/2022] Open
Abstract
The Obg protein family belongs to the TRAFAC (translation factor) class of P-loop GTPases and is conserved from bacteria to eukaryotes. Essential roles in many different cellular processes have been suggested for the Obg protein from Escherichia coli (ObgE), and we recently showed that it is a central regulator of bacterial persistence. Here, we report the first crystal structure of ObgE at 1.85-Å resolution in the GDP-bound state, showing the characteristic N-terminal domain and a central G domain that are common to all Obg proteins. ObgE also contains an intrinsically disordered C-terminal domain, and we show here that this domain specifically contributed to GTP binding, whereas it did not influence GDP binding or GTP hydrolysis. Biophysical analysis, using small angle X-ray scattering and multi-angle light scattering experiments, revealed that ObgE is a monomer in solution, regardless of the bound nucleotide. In contrast to recent suggestions, our biochemical analyses further indicate that ObgE is neither activated by K+ ions nor by homodimerization. However, the ObgE GTPase activity was stimulated upon binding to the ribosome, confirming the ribosome-dependent GTPase activity of the Obg family. Combined, our data represent an important step toward further unraveling the detailed molecular mechanism of ObgE, which might pave the way to further studies into how this GTPase regulates bacterial physiology, including persistence.
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Affiliation(s)
- Sotirios Gkekas
- From the Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels.,the VIB-VUB Center for Structural Biology, 1050 Brussels
| | - Ranjan Kumar Singh
- From the Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels.,the VIB-VUB Center for Structural Biology, 1050 Brussels
| | - Alexander V Shkumatov
- From the Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels.,the VIB-VUB Center for Structural Biology, 1050 Brussels
| | - Joris Messens
- From the Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels.,the VIB-VUB Center for Structural Biology, 1050 Brussels
| | - Maarten Fauvart
- the Centre of Microbial and Plant Genetics, KU Leuven, University of Leuven, 3001 Leuven, and.,the Department of Life Science Technologies, Smart Systems and Emerging Technologies Unit, IMEC, 3001 Leuven, Belgium
| | - Natalie Verstraeten
- the Centre of Microbial and Plant Genetics, KU Leuven, University of Leuven, 3001 Leuven, and
| | - Jan Michiels
- the Centre of Microbial and Plant Genetics, KU Leuven, University of Leuven, 3001 Leuven, and
| | - Wim Versées
- From the Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, .,the VIB-VUB Center for Structural Biology, 1050 Brussels
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12
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Fislage M, Wauters L, Versées W. Invited review: MnmE, a GTPase that drives a complex tRNA modification reaction. Biopolymers 2017; 105:568-79. [PMID: 26832457 DOI: 10.1002/bip.22813] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 01/19/2016] [Accepted: 01/27/2016] [Indexed: 01/30/2023]
Abstract
MnmE is a multi-domain GTPase that is conserved from bacteria to man. Together with its partner protein MnmG it is involved in the synthesis of a tRNA wobble uridine modification. The orthologues of these proteins in eukaryotes are targeted to mitochondria and mutations in the encoding genes are associated with severe mitochondrial diseases. While classical small GTP-binding proteins are regulated via auxiliary GEFs and GAPs, the GTPase activity of MnmE is activated via potassium-dependent homodimerization of its G domains. In this review we focus on the catalytic mechanism of GTP hydrolysis by MnmE and the large scale conformational changes that are triggered throughout the GTPase cycle. We also discuss how these conformational changes might be used to drive and tune the complex tRNA modification reaction. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 568-579, 2016.
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Affiliation(s)
- Marcus Fislage
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, 10032.,Howard Hughes Medical Institute, Columbia University, New York, NY, 10032
| | - Lina Wauters
- Department of Cell Biochemistry, University of Groningen, Nijenborgh 7, Groningen, 9747 AG, Netherlands.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, Brussel, 1050, Belgium.,Structural Biology Research Center, VIB, Pleinlaan 2, Brussel, 1050, Belgium
| | - Wim Versées
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, Brussel, 1050, Belgium.,Structural Biology Research Center, VIB, Pleinlaan 2, Brussel, 1050, Belgium
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13
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Lau CKY, Krewulak KD, Vogel HJ. Bacterial ferrous iron transport: the Feo system. FEMS Microbiol Rev 2015; 40:273-98. [PMID: 26684538 DOI: 10.1093/femsre/fuv049] [Citation(s) in RCA: 212] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2015] [Indexed: 01/24/2023] Open
Abstract
To maintain iron homeostasis within the cell, bacteria have evolved various types of iron acquisition systems. Ferric iron (Fe(3+)) is the dominant species in an oxygenated environment, while ferrous iron (Fe(2+)) is more abundant under anaerobic conditions or at low pH. For organisms that must combat oxygen limitation for their everyday survival, pathways for the uptake of ferrous iron are essential. Several bacterial ferrous iron transport systems have been described; however, only the Feo system appears to be widely distributed and is exclusively dedicated to the transport of iron. In recent years, many studies have explored the role of the FeoB and FeoA proteins in ferrous iron transport and their contribution toward bacterial virulence. The three-dimensional structures for the Feo proteins have recently been determined and provide insight into the molecular details of the transport system. A highly select group of bacteria also express the FeoC protein from the same operon. This review will provide a comprehensive look at the structural and functional aspects of the Feo system. In addition, bioinformatics analyses of the feo operon and the Feo proteins have been performed to complement our understanding of this ubiquitous bacterial uptake system, providing a new outlook for future studies.
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Affiliation(s)
- Cheryl K Y Lau
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - Karla D Krewulak
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - Hans J Vogel
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
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Armengod ME, Meseguer S, Villarroya M, Prado S, Moukadiri I, Ruiz-Partida R, Garzón MJ, Navarro-González C, Martínez-Zamora A. Modification of the wobble uridine in bacterial and mitochondrial tRNAs reading NNA/NNG triplets of 2-codon boxes. RNA Biol 2015; 11:1495-507. [PMID: 25607529 DOI: 10.4161/15476286.2014.992269] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Posttranscriptional modification of the uridine located at the wobble position (U34) of tRNAs is crucial for optimization of translation. Defects in the U34 modification of mitochondrial-tRNAs are associated with a group of rare diseases collectively characterized by the impairment of the oxidative phosphorylation system. Retrograde signaling pathways from mitochondria to nucleus are involved in the pathophysiology of these diseases. These pathways may be triggered by not only the disturbance of the mitochondrial (mt) translation caused by hypomodification of tRNAs, but also as a result of nonconventional roles of mt-tRNAs and mt-tRNA-modifying enzymes. The evolutionary conservation of these enzymes supports their importance for cell and organismal functions. Interestingly, bacterial and eukaryotic cells respond to stress by altering the expression or activity of these tRNA-modifying enzymes, which leads to changes in the modification status of tRNAs. This review summarizes recent findings about these enzymes and sets them within the previous data context.
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Affiliation(s)
- M Eugenia Armengod
- a Laboratory of RNA Modification and Mitochondrial Diseases ; Centro de Investigación Príncipe Felipe ; Valencia , Spain
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15
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Shippy DC, Fadl AA. RNA modification enzymes encoded by the gid operon: Implications in biology and virulence of bacteria. Microb Pathog 2015; 89:100-7. [PMID: 26427881 DOI: 10.1016/j.micpath.2015.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/23/2015] [Indexed: 01/10/2023]
Abstract
Ribonucleic acid (RNA) molecules consist of numerous chemically modified nucleosides that are highly conserved in eukarya, archeae, and bacteria, while others are unique to each domain of life. In bacteria, hundreds of RNA modification enzymes have been identified and implicated in biological pathways associated with many cell processes. The glucose-inhibited division (gid) operon encodes genes for two RNA modification enzymes named GidA and GidB. Studies have shown GidA is essential for the proper biosynthesis of 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U) of bacterial transfer RNA (tRNA) with GidB responsible for the methylation of the 16S ribosomal RNA (rRNA). Furthermore, deletion of gidA and gidB has shown to alter numerous bacterial properties like virulence, stress response, morphology, growth, antibiotic susceptibility, and others. In this review, we discuss the present knowledge of the RNA modification enzymes GidA and GidB, and their potential role in the biology and virulence of bacteria.
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Affiliation(s)
- Daniel C Shippy
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Amin A Fadl
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
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16
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Zhu X, He X, Wang W, Zhou Q, Yu Z, Dai Y, Zhu X, Yan Q. MTO1 worked as a modifier in the aminoglycosides sensitivity of yeast carrying a mitochondrial 15S rRNA C1477G mutation. PLoS One 2015; 10:e0124200. [PMID: 25898254 PMCID: PMC4405582 DOI: 10.1371/journal.pone.0124200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 02/26/2015] [Indexed: 01/18/2023] Open
Abstract
MTO1, together with MSS1 and MTO2, is a gene involved in the pathway of encoding a mitochondria-specific RNA-modifying enzyme related to the post-transcriptional modification of mitochondrial tRNAs. We have previously shown that a mutation of the MTO2 or MSS1 gene can suppress the neomycin-sensitive phenotype of yeast carrying a mitochondrial 15S rRNA C1477G mutation. Here we report that a null mutation of MTO1 also can inhibit the aminoglycoside-sensitivity of yeast carrying mitochondrial 15S rRNA C1477G mutation. The C1477G mutation corresponds to the human 12S rRNA A1555G mutation. Yeast with an mtDNA C1477G mutation exhibits hypersensitivity to neomycin and displays mitochondrial function impairment beyond neomycin treatment. When the mto1 null mutation and mitochondrial C1477G mutation coexist, the yeast strain shows growth recovery. The deletion of the nuclear gene MTO1 regulates neomycin sensitivity in yeast carrying the mitochondrial 15S rRNA C1477G mutation. MTO1 deletion causes the expression levels of the key glycolytic genes HXK2, PFK1 and PYK1 to become significantly up-regulated. The energy deficit due to impaired mitochondrial function was partially compensated by the energy generated by glycolysis. Being in the same pathway, the regulation of MTO1, MSS1 and MTO2 to the neomycin-sensitivity of yeast showed difference in the growth activity of strains, mitochondrial function and the expression level of glycolytic genes.
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Affiliation(s)
- Xiaoyu Zhu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Xiangyu He
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Wei Wang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Qiyin Zhou
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Zhe Yu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Yu Dai
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Xufen Zhu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Qingfeng Yan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, 310058, China
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17
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Tischner C, Hofer A, Wulff V, Stepek J, Dumitru I, Becker L, Haack T, Kremer L, Datta AN, Sperl W, Floss T, Wurst W, Chrzanowska-Lightowlers Z, De Angelis MH, Klopstock T, Prokisch H, Wenz T. MTO1 mediates tissue specificity of OXPHOS defects via tRNA modification and translation optimization, which can be bypassed by dietary intervention. Hum Mol Genet 2015; 24:2247-66. [PMID: 25552653 PMCID: PMC4380071 DOI: 10.1093/hmg/ddu743] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 12/12/2014] [Accepted: 12/22/2014] [Indexed: 11/15/2022] Open
Abstract
Mitochondrial diseases often exhibit tissue-specific pathologies, but this phenomenon is poorly understood. Here we present regulation of mitochondrial translation by the Mitochondrial Translation Optimization Factor 1, MTO1, as a novel player in this scenario. We demonstrate that MTO1 mediates tRNA modification and controls mitochondrial translation rate in a highly tissue-specific manner associated with tissue-specific OXPHOS defects. Activation of mitochondrial proteases, aberrant translation products, as well as defects in OXPHOS complex assembly observed in MTO1 deficient mice further imply that MTO1 impacts translation fidelity. In our mouse model, MTO1-related OXPHOS deficiency can be bypassed by feeding a ketogenic diet. This therapeutic intervention is independent of the MTO1-mediated tRNA modification and involves balancing of mitochondrial and cellular secondary stress responses. Our results thereby establish mammalian MTO1 as a novel factor in the tissue-specific regulation of OXPHOS and fine tuning of mitochondrial translation accuracy.
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Affiliation(s)
- Christin Tischner
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Annette Hofer
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Veronika Wulff
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Joanna Stepek
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Iulia Dumitru
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Lore Becker
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, Munich 80336, Germany, German Mouse Clinic, Institute of Experimental Genetics
| | - Tobias Haack
- Institute of Human Genetics, German Network for Mitochondrial Disorders (mitoNET), Germany
| | - Laura Kremer
- Institute of Human Genetics, German Network for Mitochondrial Disorders (mitoNET), Germany
| | - Alexandre N Datta
- Division of Neuropediatrics and Developmental Medicine, University Children's Hospital Basel (UKBB), University of Basel, Basel 4031, Switzerland
| | - Wolfgang Sperl
- German Network for Mitochondrial Disorders (mitoNET), Germany, Department of Pediatrics, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Thomas Floss
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environment and Health (GmbH), Neuherberg 85764, Germany
| | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environment and Health (GmbH), Neuherberg 85764, Germany, Technical University Munich, Helmholtz Zentrum München, Neuherberg 85764, Germany, DZNE-German Center for Neurodegenerative Diseases, Munich, Germany, Max Planck Institute of Psychiatry, Munich 80804, Germany, German Center for Vertigo and Balance Disorders, Munich, Germany
| | - Zofia Chrzanowska-Lightowlers
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, The Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Martin Hrabe De Angelis
- German Mouse Clinic, Institute of Experimental Genetics, German Center for Vertigo and Balance Disorders, Munich, Germany, Center of Life and Food Sciences Weihenstephan, Technische Universitat München, Freising 85350, Germany, German Center for Diabetes Research (DZD), Neuherberg 85764, Germany and Technische Universität München, Freising-Weihenstephan 85354, Germany
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, Munich 80336, Germany, German Mouse Clinic, Institute of Experimental Genetics, German Network for Mitochondrial Disorders (mitoNET), Germany, DZNE-German Center for Neurodegenerative Diseases, Munich, Germany, German Center for Vertigo and Balance Disorders, Munich, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environment and Health (GmbH), Neuherberg 85764, Germany
| | - Tina Wenz
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany, German Network for Mitochondrial Disorders (mitoNET), Germany,
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18
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Hori H. Methylated nucleosides in tRNA and tRNA methyltransferases. Front Genet 2014; 5:144. [PMID: 24904644 PMCID: PMC4033218 DOI: 10.3389/fgene.2014.00144] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/04/2014] [Indexed: 12/26/2022] Open
Abstract
To date, more than 90 modified nucleosides have been found in tRNA and the biosynthetic pathways of the majority of tRNA modifications include a methylation step(s). Recent studies of the biosynthetic pathways have demonstrated that the availability of methyl group donors for the methylation in tRNA is important for correct and efficient protein synthesis. In this review, I focus on the methylated nucleosides and tRNA methyltransferases. The primary functions of tRNA methylations are linked to the different steps of protein synthesis, such as the stabilization of tRNA structure, reinforcement of the codon-anticodon interaction, regulation of wobble base pairing, and prevention of frameshift errors. However, beyond these basic functions, recent studies have demonstrated that tRNA methylations are also involved in the RNA quality control system and regulation of tRNA localization in the cell. In a thermophilic eubacterium, tRNA modifications and the modification enzymes form a network that responses to temperature changes. Furthermore, several modifications are involved in genetic diseases, infections, and the immune response. Moreover, structural, biochemical, and bioinformatics studies of tRNA methyltransferases have been clarifying the details of tRNA methyltransferases and have enabled these enzymes to be classified. In the final section, the evolution of modification enzymes is discussed.
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Affiliation(s)
- Hiroyuki Hori
- Department of Materials Science and Biotechnology, Applied Chemistry, Graduate School of Science and Engineering, Ehime University Matsuyama, Japan
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19
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Fislage M, Brosens E, Deyaert E, Spilotros A, Pardon E, Loris R, Steyaert J, Garcia-Pino A, Versées W. SAXS analysis of the tRNA-modifying enzyme complex MnmE/MnmG reveals a novel interaction mode and GTP-induced oligomerization. Nucleic Acids Res 2014; 42:5978-92. [PMID: 24634441 PMCID: PMC4027165 DOI: 10.1093/nar/gku213] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 02/28/2014] [Accepted: 02/28/2014] [Indexed: 11/12/2022] Open
Abstract
Transfer ribonucleic acid (tRNA) modifications, especially at the wobble position, are crucial for proper and efficient protein translation. MnmE and MnmG form a protein complex that is implicated in the carboxymethylaminomethyl modification of wobble uridine (cmnm(5)U34) of certain tRNAs. MnmE is a G protein activated by dimerization (GAD), and active guanosine-5'-triphosphate (GTP) hydrolysis is required for the tRNA modification to occur. Although crystal structures of MnmE and MnmG are available, the structure of the MnmE/MnmG complex (MnmEG) and the nature of the nucleotide-induced conformational changes and their relevance for the tRNA modification reaction remain unknown. In this study, we mainly used small-angle X-ray scattering to characterize these conformational changes in solution and to unravel the mode of interaction between MnmE, MnmG and tRNA. In the nucleotide-free state MnmE and MnmG form an unanticipated asymmetric α2β2 complex. Unexpectedly, GTP binding promotes further oligomerization of the MnmEG complex leading to an α4β2 complex. The transition from the α2β2 to the α4β2 complex is fast, reversible and coupled to GTP binding and hydrolysis. We propose a model in which the nucleotide-induced changes in conformation and oligomerization of MnmEG form an integral part of the tRNA modification reaction cycle.
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Affiliation(s)
- Marcus Fislage
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
| | - Elke Brosens
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
| | - Egon Deyaert
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
| | - Alessandro Spilotros
- EMBL Hamburg outstation c/o DESY, Notkestrasse 85, Geb. 25A, 22603 Hamburg, Germany
| | - Els Pardon
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
| | - Remy Loris
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
| | - Jan Steyaert
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
| | - Abel Garcia-Pino
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
| | - Wim Versées
- Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
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Posttranscriptional regulation of 2,4-diacetylphloroglucinol production by GidA and TrmE in Pseudomonas fluorescens 2P24. Appl Environ Microbiol 2014; 80:3972-81. [PMID: 24747907 DOI: 10.1128/aem.00455-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas fluorescens 2P24 is a soilborne bacterium that synthesizes and excretes multiple antimicrobial metabolites. The polyketide compound 2,4-diacetylphloroglucinol (2,4-DAPG), synthesized by the phlACBD locus, is its major biocontrol determinant. This study investigated two mutants defective in antagonistic activity against Rhizoctonia solani. Deletion of the gidA (PM701) or trmE (PM702) gene from strain 2P24 completely inhibited the production of 2,4-DAPG and its precursors, monoacetylphloroglucinol (MAPG) and phloroglucinol (PG). The transcription of the phlA gene was not affected, but the translation of the phlA and phlD genes was reduced significantly. Two components of the Gac/Rsm pathway, RsmA and RsmE, were found to be regulated by gidA and trmE, whereas the other components, RsmX, RsmY, and RsmZ, were not. The regulation of 2,4-DAPG production by gidA and trmE, however, was independent of the Gac/Rsm pathway. Both the gidA and trmE mutants were unable to produce PG but could convert PG to MAPG and MAPG to 2,4-DAPG. Overexpression of PhlD in the gidA and trmE mutants could restore the production of PG and 2,4-DAPG. Taken together, these findings suggest that GidA and TrmE are positive regulatory elements that influence the biosynthesis of 2,4-DAPG posttranscriptionally.
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21
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Prado S, Villarroya M, Medina M, Armengod ME. The tRNA-modifying function of MnmE is controlled by post-hydrolysis steps of its GTPase cycle. Nucleic Acids Res 2013; 41:6190-208. [PMID: 23630314 PMCID: PMC3695501 DOI: 10.1093/nar/gkt320] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
MnmE is a homodimeric multi-domain GTPase involved in tRNA modification. This protein differs from Ras-like GTPases in its low affinity for guanine nucleotides and mechanism of activation, which occurs by a cis, nucleotide- and potassium-dependent dimerization of its G-domains. Moreover, MnmE requires GTP hydrolysis to be functionally active. However, how GTP hydrolysis drives tRNA modification and how the MnmE GTPase cycle is regulated remains unresolved. Here, the kinetics of the MnmE GTPase cycle was studied under single-turnover conditions using stopped- and quench-flow techniques. We found that the G-domain dissociation is the rate-limiting step of the overall reaction. Mutational analysis and fast kinetics assays revealed that GTP hydrolysis, G-domain dissociation and Pi release can be uncoupled and that G-domain dissociation is directly responsible for the ‘ON’ state of MnmE. Thus, MnmE provides a new paradigm of how the ON/OFF cycling of GTPases may regulate a cellular process. We also demonstrate that the MnmE GTPase cycle is negatively controlled by the reaction products GDP and Pi. This feedback mechanism may prevent inefficacious GTP hydrolysis in vivo. We propose a biological model whereby a conformational change triggered by tRNA binding is required to remove product inhibition and initiate a new GTPase/tRNA-modification cycle.
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Affiliation(s)
- Silvia Prado
- RNA Modification and Mitochondrial Diseases Laboratory, Centro de Investigación Príncipe Felipe, 46012-Valencia, Spain
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22
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Shippy DC, Eakley NM, Lauhon CT, Bochsler PN, Fadl AA. Virulence characteristics of Salmonella following deletion of genes encoding the tRNA modification enzymes GidA and MnmE. Microb Pathog 2013; 57:1-9. [DOI: 10.1016/j.micpath.2013.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 01/11/2013] [Accepted: 01/14/2013] [Indexed: 12/25/2022]
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23
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Luo LF, Hou CC, Yang WX. Nuclear factors: roles related to mitochondrial deafness. Gene 2013; 520:79-89. [PMID: 23510774 DOI: 10.1016/j.gene.2013.03.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 03/08/2013] [Indexed: 12/16/2022]
Abstract
Hearing loss (HL) is a common disorder with mitochondrial dysfunction as one of the major causes leading to deafness. Mitochondrial dysfunction may be caused by either mutations in nuclear genes leading to defective nuclear-encoded proteins or mutations in mitochondrial genes leading to defective mitochondrial-encoded products. The specific nuclear genes involved in HL can be classified into two categories depending on whether mitochondrial gene mutations co-exist (modifier genes) or not (deafness-causing genes). TFB1M, MTO1, GTPBP3, and TRMU are modifier genes. A mutation in any of these modifier genes may lead to a deafness phenotype when accompanied by the mitochondrial gene mutation. OPA1, TIMM8A, SMAC/DIABLO, MPV17, PDSS1, BCS1L, SUCLA2, C10ORF2, COX10, PLOG1and RRM2B are deafness-causing genes. A mutation in any of these deafness-causing genes will directly induce variable phenotypic HL.
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Affiliation(s)
- Ling-Feng Luo
- Institute of Cell and Developmental Biology, Zhejiang University, Hangzhou 310058, China
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24
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El Yacoubi B, Bailly M, de Crécy-Lagard V. Biosynthesis and Function of Posttranscriptional Modifications of Transfer RNAs. Annu Rev Genet 2012; 46:69-95. [DOI: 10.1146/annurev-genet-110711-155641] [Citation(s) in RCA: 380] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Basma El Yacoubi
- Department of Microbiology and Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611-0700;
| | - Marc Bailly
- Department of Microbiology and Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611-0700;
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611-0700;
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25
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Shippy DC, Fadl AA. Immunological characterization of a gidA mutant strain of Salmonella for potential use in a live-attenuated vaccine. BMC Microbiol 2012. [PMID: 23194372 PMCID: PMC3520829 DOI: 10.1186/1471-2180-12-286] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Salmonella is often associated with gastrointestinal disease outbreaks in humans throughout the world due to the consumption of contaminated food. Our previous studies have shown that deletion of glucose-inhibited division gene (gidA) significantly attenuated Salmonella enterica serovar Typhimurium (STM) virulence in both in vitro and in vivo models of infection. Most importantly, immunization with the gidA mutant protected mice from a lethal dose challenge of wild-type STM. In this study, we further characterize the gidA mutant STM strain for potential use in a live-attenuated vaccine. Results The protective efficacy of immunization with the gidA mutant was evaluated by challenging immunized mice with a lethal dose of wild-type STM. Sera levels of IgG2a and IgG1, passive transfer of sera and cells, and cytokine profiling were performed to study the induction of humoral and cellular immune responses induced by immunization with the gidA mutant strain. Additionally, a lymphocyte proliferation assay was performed to gauge the splenocyte survival in response to treatment with STM cell lysate. Mice immunized with the gidA mutant strain were fully protected from a lethal dose challenge of wild-type STM. Naïve mice receiving either cells or sera from immunized mice were partially protected from a lethal dose challenge of wild-type STM. The lymphocyte proliferation assay displayed a significant response of splenocytes from immunized mice when compared to splenocytes from non-immunized control mice. Furthermore, the immunized mice displayed significantly higher levels of IgG1 and IgG2a with a marked increase in IgG1. Additionally, immunization with the gidA mutant strain evoked higher levels of IL-2, IFN-γ, and IL-10 cytokines in splenocytes induced with STM cell lysate. Conclusions Together, the results demonstrate that immunization with the gidA mutant strain protects mice by inducing humoral and cellular immune responses with the humoral immune response potentially being the main mechanism of protection.
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Affiliation(s)
- Daniel C Shippy
- Department of Animal Sciences, University of Wisconsin-Madison, 1675 Observatory Dr, Madison, WI 53706, USA
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26
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Kitamura A, Nishimoto M, Sengoku T, Shibata R, Jäger G, Björk GR, Grosjean H, Yokoyama S, Bessho Y. Characterization and structure of the Aquifex aeolicus protein DUF752: a bacterial tRNA-methyltransferase (MnmC2) functioning without the usually fused oxidase domain (MnmC1). J Biol Chem 2012; 287:43950-60. [PMID: 23091054 PMCID: PMC3527978 DOI: 10.1074/jbc.m112.409300] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Post-transcriptional modifications of the wobble uridine (U34) of tRNAs play a critical role in reading NNA/G codons belonging to split codon boxes. In a subset of Escherichia coli tRNA, this wobble uridine is modified to 5-methylaminomethyluridine (mnm5U34) through sequential enzymatic reactions. Uridine 34 is first converted to 5-carboxymethylaminomethyluridine (cmnm5U34) by the MnmE-MnmG enzyme complex. The cmnm5U34 is further modified to mnm5U by the bifunctional MnmC protein. In the first reaction, the FAD-dependent oxidase domain (MnmC1) converts cmnm5U into 5-aminomethyluridine (nm5U34), and this reaction is immediately followed by the methylation of the free amino group into mnm5U34 by the S-adenosylmethionine-dependent domain (MnmC2). Aquifex aeolicus lacks a bifunctional MnmC protein fusion and instead encodes the Rossmann-fold protein DUF752, which is homologous to the methyltransferase MnmC2 domain of Escherichia coli MnmC (26% identity). Here, we determined the crystal structure of the A. aeolicus DUF752 protein at 2.5 Å resolution, which revealed that it catalyzes the S-adenosylmethionine-dependent methylation of nm5U in vitro, to form mnm5U34 in tRNA. We also showed that naturally occurring tRNA from A. aeolicus contains the 5-mnm group attached to the C5 atom of U34. Taken together, these results support the recent proposal of an alternative MnmC1-independent shortcut pathway for producing mnm5U34 in tRNAs.
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Affiliation(s)
- Aya Kitamura
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
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27
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Becker M, Gzyl KE, Altamirano AM, Vuong A, Urbahn K, Wieden HJ. The 70S ribosome modulates the ATPase activity of Escherichia coli YchF. RNA Biol 2012; 9:1288-301. [PMID: 22995830 PMCID: PMC3583859 DOI: 10.4161/rna.22131] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
YchF is one of two universally conserved GTPases with unknown cellular function. As a first step toward elucidating YchF's cellular role, we performed a detailed biochemical characterization of the protein from Escherichia coli. Our data from fluorescence titrations not only confirmed the surprising finding that YchFE.coli binds adenine nucleotides more efficiently than guanine nucleotides, but also provides the first evidence suggesting that YchF assumes two distinct conformational states (ATP- and ADP-bound) consistent with the functional cycle of a typical GTPase. Based on an in vivo pull-down experiment using a His-tagged variant of YchF from E. coli (YchFE.coli), we were able to isolate a megadalton complex containing the 70S ribosome. Based on this finding, we report the successful reconstitution of a YchF•70S complex in vitro, revealing an affinity (KD) of the YchFE.coli•ADPNP complex for 70S ribosomes of 3 μM. The in vitro reconstitution data also suggests that the identity of the nucleotide-bound state of YchF (ADP or ATP) modulates its affinity for 70S ribosomes. A detailed Michaelis-Menten analysis of YchF's catalytic activity in the presence and the absence of the 70S ribosome and its subunits revealed for the first time that the 70S ribosome is able to stimulate YchF's ATPase activity (~10-fold), confirming the ribosome as part of the functional cycle of YchF. Our findings taken together with previously reported data for the human homolog of YchF (hOLA1) indicate a high level of evolutionary conservation in the enzymatic properties of YchF and suggest that the ribosome is the main functional partner of YchF not only in bacteria.
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Affiliation(s)
- Marion Becker
- Department of Chemistry and Biochemistry; University of Lethbridge; Lethbridge, AB Canada
| | - Katherine E. Gzyl
- Department of Chemistry and Biochemistry; University of Lethbridge; Lethbridge, AB Canada
| | - Alvin M. Altamirano
- Department of Chemistry and Biochemistry; University of Lethbridge; Lethbridge, AB Canada
| | - Anthony Vuong
- Department of Chemistry and Biochemistry; University of Lethbridge; Lethbridge, AB Canada
| | - Kirstin Urbahn
- Department of Chemistry and Biochemistry; University of Lethbridge; Lethbridge, AB Canada
| | - Hans-Joachim Wieden
- Department of Chemistry and Biochemistry; University of Lethbridge; Lethbridge, AB Canada
- Alberta RNA Research and Training Institute; University of Lethbridge; Lethbridge, AB Canada
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28
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Armengod ME, Moukadiri I, Prado S, Ruiz-Partida R, Benítez-Páez A, Villarroya M, Lomas R, Garzón MJ, Martínez-Zamora A, Meseguer S, Navarro-González C. Enzymology of tRNA modification in the bacterial MnmEG pathway. Biochimie 2012; 94:1510-20. [PMID: 22386868 DOI: 10.1016/j.biochi.2012.02.019] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 02/16/2012] [Indexed: 10/28/2022]
Abstract
Among all RNAs, tRNA exhibits the largest number and the widest variety of post-transcriptional modifications. Modifications within the anticodon stem loop, mainly at the wobble position and purine-37, collectively contribute to stabilize the codon-anticodon pairing, maintain the translational reading frame, facilitate the engagement of the ribosomal decoding site and enable translocation of tRNA from the A-site to the P-site of the ribosome. Modifications at the wobble uridine (U34) of tRNAs reading two degenerate codons ending in purine are complex and result from the activity of two multi-enzyme pathways, the IscS-MnmA and MnmEG pathways, which independently work on positions 2 and 5 of the U34 pyrimidine ring, respectively, and from a third pathway, controlled by TrmL (YibK), that modifies the 2'-hydroxyl group of the ribose. MnmEG is the only common pathway to all the mentioned tRNAs, and involves the GTP- and FAD-dependent activity of the MnmEG complex and, in some cases, the activity of the bifunctional enzyme MnmC. The Escherichia coli MnmEG complex catalyzes the incorporation of an aminomethyl group into the C5 atom of U34 using methylene-tetrahydrofolate and glycine or ammonium as donors. The reaction requires GTP hydrolysis, probably to assemble the active site of the enzyme or to carry out substrate recognition. Inactivation of the evolutionarily conserved MnmEG pathway produces a pleiotropic phenotype in bacteria and mitochondrial dysfunction in human cell lines. While the IscS-MnmA pathway and the MnmA-mediated thiouridylation reaction are relatively well understood, we have limited information on the reactions mediated by the MnmEG, MnmC and TrmL enzymes and on the precise role of proteins MnmE and MnmG in the MnmEG complex activity. This review summarizes the present state of knowledge on these pathways and what we still need to know, with special emphasis on the MnmEG pathway.
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Affiliation(s)
- M-Eugenia Armengod
- Laboratorio de Genética Molecular, Centro de Investigación Príncipe Felipe, Molecular Genetics, Avenida Autopista del Saler, 16-3, 46012-Valencia, Spain.
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29
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The universally conserved prokaryotic GTPases. Microbiol Mol Biol Rev 2012; 75:507-42, second and third pages of table of contents. [PMID: 21885683 DOI: 10.1128/mmbr.00009-11] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Members of the large superclass of P-loop GTPases share a core domain with a conserved three-dimensional structure. In eukaryotes, these proteins are implicated in various crucial cellular processes, including translation, membrane trafficking, cell cycle progression, and membrane signaling. As targets of mutation and toxins, GTPases are involved in the pathogenesis of cancer and infectious diseases. In prokaryotes also, it is hard to overestimate the importance of GTPases in cell physiology. Numerous papers have shed new light on the role of bacterial GTPases in cell cycle regulation, ribosome assembly, the stress response, and other cellular processes. Moreover, bacterial GTPases have been identified as high-potential drug targets. A key paper published over 2 decades ago stated that, "It may never again be possible to capture [GTPases] in a family portrait" (H. R. Bourne, D. A. Sanders, and F. McCormick, Nature 348:125-132, 1990) and indeed, the last 20 years have seen a tremendous increase in publications on the subject. Sequence analysis identified 13 bacterial GTPases that are conserved in at least 75% of all bacterial species. We here provide an overview of these 13 protein subfamilies, covering their cellular functions as well as cellular localization and expression levels, three-dimensional structures, biochemical properties, and gene organization. Conserved roles in eukaryotic homologs will be discussed as well. A comprehensive overview summarizing current knowledge on prokaryotic GTPases will aid in further elucidating the function of these important proteins.
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30
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Suzuki T, Nagao A, Suzuki T. Human Mitochondrial tRNAs: Biogenesis, Function, Structural Aspects, and Diseases. Annu Rev Genet 2011; 45:299-329. [DOI: 10.1146/annurev-genet-110410-132531] [Citation(s) in RCA: 413] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Mitochondria are eukaryotic organelles that generate most of the energy in the cell by oxidative phosphorylation (OXPHOS). Each mitochondrion contains multiple copies of a closed circular double-stranded DNA genome (mtDNA). Human (mammalian) mtDNA encodes 13 essential subunits of the inner membrane complex responsible for OXPHOS. These mRNAs are translated by the mitochondrial protein synthesis machinery, which uses the 22 species of mitochondrial tRNAs (mt tRNAs) encoded by mtDNA. The unique structural features of mt tRNAs distinguish them from cytoplasmic tRNAs bearing the canonical cloverleaf structure. The genes encoding mt tRNAs are highly susceptible to point mutations, which are a primary cause of mitochondrial dysfunction and are associated with a wide range of pathologies. A large number of nuclear factors involved in the biogenesis and function of mt tRNAs have been identified and characterized, including processing endonucleases, tRNA-modifying enzymes, and aminoacyl-tRNA synthetases. These nuclear factors are also targets of pathogenic mutations linked to various diseases, indicating the functional importance of mt tRNAs for mitochondrial activity.
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Affiliation(s)
| | - Asuteka Nagao
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
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31
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Bulyha I, Hot E, Huntley S, Søgaard-Andersen L. GTPases in bacterial cell polarity and signalling. Curr Opin Microbiol 2011; 14:726-33. [DOI: 10.1016/j.mib.2011.09.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 08/31/2011] [Accepted: 09/05/2011] [Indexed: 12/20/2022]
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32
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Deletion of glucose-inhibited division (gidA) gene alters the morphological and replication characteristics of Salmonella enterica Serovar typhimurium. Arch Microbiol 2011; 194:405-12. [PMID: 22109813 DOI: 10.1007/s00203-011-0769-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/15/2011] [Accepted: 11/01/2011] [Indexed: 10/15/2022]
Abstract
Salmonella is an important food-borne pathogen that continues to plague the United States food industry. Characterization of bacterial factors involved in food-borne illnesses could help develop new ways to control salmonellosis. We have previously shown that deletion of glucose-inhibited division gene (gidA) significantly altered the virulence potential of Salmonella in both in vitro and in vivo models of infection. Most importantly, the gidA mutant cells displayed a filamentous morphology compared to the wild-type Salmonella cells. In our current study, we investigated the role of GidA in Salmonella cell division using fluorescence and electron microscopy, transcriptional, and proteomic assays. Scanning electron microscopy data indicated a filamentous morphology with few constrictions in the gidA mutant cells. The filamentation of the gidA mutant cells is most likely due to the defect in chromosome segregation, with little to no sign of septa formation observed using fluorescence and transmission electron microscopy. Furthermore, deletion of gidA altered the expression of many genes and proteins responsible for cell division and chromosome segregation as indicated by global transcriptional profiling and semi-quantitative western blot analysis. Taken together, our data indicate GidA as a potential regulator of Salmonella cell division genes.
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33
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Kitamura A, Sengoku T, Nishimoto M, Yokoyama S, Bessho Y. Crystal structure of the bifunctional tRNA modification enzyme MnmC from Escherichia coli. Protein Sci 2011; 20:1105-13. [PMID: 21574198 DOI: 10.1002/pro.659] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 04/30/2011] [Accepted: 05/02/2011] [Indexed: 11/10/2022]
Abstract
Post-transcriptional modifications of bases within the transfer RNAs (tRNA) anticodon significantly affect the decoding system. In bacteria and eukaryotes, uridines at the wobble position (U34) of some tRNAs are modified to 5-methyluridine derivatives (xm⁵U). These xm⁵U34-containing tRNAs read codons ending with A or G, whereas tRNAs with the unmodified U34 are able to read all four synonymous codons of a family box. In Escherichia coli (E.coli), the bifunctional enzyme MnmC catalyzes the two consecutive reactions that convert 5-carboxymethylaminomethyl uridine (cmnm⁵U) to 5-methylaminomethyl uridine (mnm⁵U). The C-terminal domain of MnmC (MnmC1) is responsible for the flavin adenine dinucleotide (FAD)-dependent deacetylation of cmnm⁵U to 5-aminomethyl uridine (nm⁵U), whereas the N-terminal domain (MnmC2) catalyzes the subsequent S-adenosyl-L-methionine-dependent methylation of nm⁵U, leading to the final product, mnm⁵U34. Here, we determined the crystal structure of E.coli MnmC containing FAD, at 3.0 Å resolution. The structure of the MnmC1 domain can be classified in the FAD-dependent glutathione reductase 2 structural family, including the glycine oxidase ThiO, whereas the MnmC2 domain adopts the canonical class I methyltransferase fold. A structural comparison with ThiO revealed the residues that may be involved in cmnm⁵U recognition, supporting previous mutational analyses. The catalytic sites of the two reactions are both surrounded by conserved basic residues for possible anticodon binding, and are located far away from each other, on opposite sides of the protein. These results suggest that, although the MnmC1 and MnmC2 domains are physically linked, they could catalyze the two consecutive reactions in a rather independent manner.
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Affiliation(s)
- Aya Kitamura
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
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34
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Shippy DC, Eakley NM, Bochsler PN, Chopra AK, Fadl AA. Biological and virulence characteristics of Salmonella enterica serovar Typhimurium following deletion of glucose-inhibited division (gidA) gene. Microb Pathog 2011; 50:303-13. [PMID: 21320585 DOI: 10.1016/j.micpath.2011.02.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Revised: 01/29/2011] [Accepted: 02/04/2011] [Indexed: 01/03/2023]
Abstract
Salmonella enterica serovar Typhimurium is a frequent cause of enteric disease due to the consumption of contaminated food. Identification and characterization of bacterial factors involved in Salmonella pathogenesis would help develop effective strategies for controlling salmonellosis. To investigate the role of glucose-inhibited division gene (gidA) in Salmonella virulence, we constructed a Salmonella mutant strain in which gidA was deleted. Deletion of gidA rendered Salmonella deficient in the invasion of intestinal epithelial cells, bacterial motility, intracellular survival, and induction of cytotoxicity in host cells. Deletion of gidA rendered the organism to display a filamentous morphology compared to the normal rod-shaped nature of Salmonella. Furthermore, a significant attenuation in the induction of inflammatory cytokines and chemokines, histopathological lesions, and systemic infection was observed in mice infected with the gidA mutant. Most importantly, a significant increase in LD(50) was observed in mice infected with the gidA mutant, and mice immunized with the gidA mutant were able to survive a lethal dose of wild-type Salmonella. Additionally, deletion of gidA significantly altered the expression of several bacterial factors associated with pathogenesis as indicated by global transcriptional and proteomic profiling. Taken together, our data indicate GidA as a potential regulator of Salmonella virulence genes.
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Affiliation(s)
- Daniel C Shippy
- Department of Animal Sciences, University of Wisconsin-Madison, 1675 Observatory Dr., Madison, WI 53706, United States
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35
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Ash MR, Guilfoyle A, Clarke RJ, Guss JM, Maher MJ, Jormakka M. Potassium-activated GTPase reaction in the G Protein-coupled ferrous iron transporter B. J Biol Chem 2010; 285:14594-602. [PMID: 20220129 PMCID: PMC2863241 DOI: 10.1074/jbc.m110.111914] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/01/2010] [Indexed: 12/22/2022] Open
Abstract
FeoB is a prokaryotic membrane protein responsible for the import of ferrous iron (Fe(2+)). A defining feature of FeoB is that it includes an N-terminal 30-kDa soluble domain with GTPase activity, which is required for iron transport. However, the low intrinsic GTP hydrolysis rate of this domain appears to be too slow for FeoB either to function as a channel or to possess an active Fe(2+) membrane transport mechanism. Here, we present crystal structures of the soluble domain of FeoB from Streptococcus thermophilus in complex with GDP and with the GTP analogue derivative 2'-(or -3')-O-(N-methylanthraniloyl)-beta,gamma-imidoguanosine 5'-triphosphate (mant-GMPPNP). Unlike recent structures of the G protein domain, the mant-GMPPNP-bound structure shows clearly resolved, active conformations of the critical Switch motifs. Importantly, biochemical analyses demonstrate that the GTPase activity of FeoB is activated by K(+), which leads to a 20-fold acceleration in its hydrolysis rate. Analysis of the structure identified a conserved asparagine residue likely to be involved in K(+) coordination, and mutation of this residue abolished K(+)-dependent activation. We suggest that this, together with a second asparagine residue that we show is critical for the structure of the Switch I loop, allows the prediction of K(+)-dependent activation in G proteins. In addition, the accelerated hydrolysis rate opens up the possibility that FeoB might indeed function as an active transporter.
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Affiliation(s)
| | - Amy Guilfoyle
- From the Structural Biology Program, Centenary Institute, Sydney, New South Wales 2042, Australia
| | | | | | - Megan J. Maher
- From the Structural Biology Program, Centenary Institute, Sydney, New South Wales 2042, Australia
| | - Mika Jormakka
- From the Structural Biology Program, Centenary Institute, Sydney, New South Wales 2042, Australia
- the Faculty of Medicine, Central Clinical School, University of Sydney, Sydney, New South Wales 2006, Australia
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36
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Böhme S, Meyer S, Krüger A, Steinhoff HJ, Wittinghofer A, Klare JP. Stabilization of G domain conformations in the tRNA-modifying MnmE-GidA complex observed with double electron electron resonance spectroscopy. J Biol Chem 2010; 285:16991-7000. [PMID: 20353943 DOI: 10.1074/jbc.m109.096131] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MnmE is a GTP-binding protein conserved between bacteria and eukarya. It is a dimeric three-domain protein where the two G domains have to approach each other for activation of the potassium-stimulated GTPase reaction. Together with GidA, in a heterotetrameric alpha(2)beta(2) complex, it is involved in the modification of the wobble uridine base U34 of the first anticodon position of particular tRNAs. Here we show, using various spin-labeled MnmE mutants and EPR spectroscopy, that GidA binding induces large conformational and dynamic changes in MnmE. It stimulates the GTPase reaction by stabilizing the GTP-bound conformation in a potassium-independent manner. Surprisingly, GidA binding influences not only the GTP- but also the GDP-bound conformation. Thus GidA is a new type of regulator for a G protein activated by dimerization.
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Affiliation(s)
- Sabine Böhme
- Department of Physics, University of Osnabrück, Barbarastrasse 7, D-49076 Osnabrück, Germany
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37
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Meyer S, Böhme S, Krüger A, Steinhoff HJ, Klare JP, Wittinghofer A. Kissing G domains of MnmE monitored by X-ray crystallography and pulse electron paramagnetic resonance spectroscopy. PLoS Biol 2009; 7:e1000212. [PMID: 19806182 PMCID: PMC2749940 DOI: 10.1371/journal.pbio.1000212] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 08/21/2009] [Indexed: 11/19/2022] Open
Abstract
The authors of this research article demonstrate the nature of the conformational changes MnmE was previously suggested to undergo during its GTPase cycle, and show the nucleotide-dependent dynamic movements of the G domains around two swivel positions relative to the rest of the protein. These movements are of crucial importance for understanding the mechanistic principles of this GAD. MnmE, which is involved in the modification of the wobble position of certain tRNAs, belongs to the expanding class of G proteins activated by nucleotide-dependent dimerization (GADs). Previous models suggested the protein to be a multidomain protein whose G domains contact each other in a nucleotide dependent manner. Here we employ a combined approach of X-ray crystallography and pulse electron paramagnetic resonance (EPR) spectroscopy to show that large domain movements are coupled to the G protein cycle of MnmE. The X-ray structures show MnmE to be a constitutive homodimer where the highly mobile G domains face each other in various orientations but are not in close contact as suggested by the GDP-AlFx structure of the isolated domains. Distance measurements by pulse double electron-electron resonance (DEER) spectroscopy show that the G domains adopt an open conformation in the nucleotide free/GDP-bound and an open/closed two-state equilibrium in the GTP-bound state, with maximal distance variations of 18 Å. With GDP and AlFx, which mimic the transition state of the phosphoryl transfer reaction, only the closed conformation is observed. Dimerization of the active sites with GDP-AlFx requires the presence of specific monovalent cations, thus reflecting the requirements for the GTPase reaction of MnmE. Our results directly demonstrate the nature of the conformational changes MnmE was previously suggested to undergo during its GTPase cycle. They show the nucleotide-dependent dynamic movements of the G domains around two swivel positions relative to the rest of the protein, and they are of crucial importance for understanding the mechanistic principles of this GAD. MnmE is an evolutionary conserved G protein that is involved in modification of the wobble U position of certain tRNAs to suppress translational wobbling. Despite high homology between its G domain and the small G protein Ras, MnmE displays entirely different regulatory properties to that of many molecular switch-type G proteins of the Ras superfamily, as its GTPase is activated by nucleotide-dependent homodimerization across the nucleotide-binding site. Here we explore the unusual G domain cycle of the MnmE protein by combining X-ray crystallography with pulse electron paramagnetic resonance (EPR) spectroscopy, which enables distance determinations between spin markers introduced at specific sites within the G domain. We determined the structures of the full-length MnmE dimer in the diphosphate and triphosphate states, which represent distinct steps of the G domain cycle, and demonstrate that the G domain cycle of MnmE comprises large conformational changes and domain movements of up to 18 Å, in which the G domains of the dimeric protein traverse from a GDP-bound open state through an open/closed equilibrium in the triphosphate state to a closed conformation in the transition state, so as to assemble the catalytic machinery.
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Affiliation(s)
- Simon Meyer
- Department of Structural Biology, Max-Planck-Institute of Molecular Physiology, Dortmund, Germany
| | - Sabine Böhme
- Department of Physics, University of Osnabrück, Osnabrück, Germany
| | - André Krüger
- Department of Structural Biology, Max-Planck-Institute of Molecular Physiology, Dortmund, Germany
| | | | - Johann P. Klare
- Department of Physics, University of Osnabrück, Osnabrück, Germany
- * E-mail: (JPK); (AW)
| | - Alfred Wittinghofer
- Department of Structural Biology, Max-Planck-Institute of Molecular Physiology, Dortmund, Germany
- * E-mail: (JPK); (AW)
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