1
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Kumar P, Babu K, Singh A, Singh D, Nalli A, Mukul S, Roy A, Mazeed M, Raman B, Kruparani S, Siddiqi I, Sankaranarayanan R. Distinct localization of chiral proofreaders resolves organellar translation conflict in plants. Proc Natl Acad Sci U S A 2023; 120:e2219292120. [PMID: 37276405 PMCID: PMC10268278 DOI: 10.1073/pnas.2219292120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 05/03/2023] [Indexed: 06/07/2023] Open
Abstract
Plants have two endosymbiotic organelles originated from two bacterial ancestors. The transition from an independent bacterium to a successful organelle would have required extensive rewiring of biochemical networks for its integration with archaeal host. Here, using Arabidopsis as a model system, we show that plant D-aminoacyl-tRNA deacylase 1 (DTD1), of bacterial origin, is detrimental to organellar protein synthesis owing to its changed tRNA recognition code. Plants survive this conflict by spatially restricting the conflicted DTD1 to the cytosol. In addition, plants have targeted archaeal DTD2 to both the organelles as it is compatible with their translation machinery due to its strict D-chiral specificity and lack of tRNA determinants. Intriguingly, plants have confined bacterial-derived DTD1 to work in archaeal-derived cytosolic compartment whereas archaeal DTD2 is targeted to bacterial-derived organelles. Overall, the study provides a remarkable example of the criticality of optimization of biochemical networks for survival and evolution of plant mitochondria and chloroplast.
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Affiliation(s)
- Pradeep Kumar
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
- Academy of Scientific and Innovative Research, Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB) campus, Hyderabad500007, India
| | - Kandhalu Sagadevan Dinesh Babu
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Avinash Kumar Singh
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Dipesh Kumar Singh
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Aswan Nalli
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Shivapura Jagadeesha Mukul
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
- Academy of Scientific and Innovative Research, Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB) campus, Hyderabad500007, India
| | - Ankit Roy
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Mohd Mazeed
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Bakthisaran Raman
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Shobha P. Kruparani
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
| | - Imran Siddiqi
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
- Academy of Scientific and Innovative Research, Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB) campus, Hyderabad500007, India
| | - Rajan Sankaranarayanan
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB), Hyderabad500007, India
- Academy of Scientific and Innovative Research, Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR–CCMB) campus, Hyderabad500007, India
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2
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Banreti A, Bhattacharya S, Wien F, Matsuo K, Réfrégiers M, Meinert C, Meierhenrich U, Hudry B, Thompson D, Noselli S. Biological effects of the loss of homochirality in a multicellular organism. Nat Commun 2022; 13:7059. [PMID: 36400783 PMCID: PMC9674851 DOI: 10.1038/s41467-022-34516-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 10/27/2022] [Indexed: 11/19/2022] Open
Abstract
Homochirality is a fundamental feature of all known forms of life, maintaining biomolecules (amino-acids, proteins, sugars, nucleic acids) in one specific chiral form. While this condition is central to biology, the mechanisms by which the adverse accumulation of non-L-α-amino-acids in proteins lead to pathophysiological consequences remain poorly understood. To address how heterochirality build-up impacts organism's health, we use chiral-selective in vivo assays to detect protein-bound non-L-α-amino acids (focusing on aspartate) and assess their functional significance in Drosophila. We find that altering the in vivo chiral balance creates a 'heterochirality syndrome' with impaired caspase activity, increased tumour formation, and premature death. Our work shows that preservation of homochirality is a key component of protein function that is essential to maintain homeostasis across the cell, tissue and organ level.
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Affiliation(s)
- Agnes Banreti
- grid.461605.0Université Côte d’Azur, CNRS, Inserm, Institut de Biologie Valrose, 06108 Nice, France
| | - Shayon Bhattacharya
- grid.10049.3c0000 0004 1936 9692Department of Physics, Bernal Institute, University of Limerick, V94 T9PX Limerick, Ireland
| | - Frank Wien
- grid.426328.9DISCO Beamline, Synchrotron SOLEIL, 91192 Gif-sur-Yvette, France
| | - Koichi Matsuo
- grid.257022.00000 0000 8711 3200HiSOR Hiroshima Synchrotron Radiation Center, Hiroshima University, Hiroshima, Japan
| | - Matthieu Réfrégiers
- grid.417870.d0000 0004 0614 8532Centre de Biophysique Moléculaire, CNRS; UPR4301, 45071 Orléans, France
| | - Cornelia Meinert
- grid.462124.70000 0004 0384 8488Université Côte d’Azur, Institut de Chimie de Nice, CNRS; UMR 7272, 06108 Nice, France
| | - Uwe Meierhenrich
- grid.462124.70000 0004 0384 8488Université Côte d’Azur, Institut de Chimie de Nice, CNRS; UMR 7272, 06108 Nice, France
| | - Bruno Hudry
- grid.461605.0Université Côte d’Azur, CNRS, Inserm, Institut de Biologie Valrose, 06108 Nice, France
| | - Damien Thompson
- grid.10049.3c0000 0004 1936 9692Department of Physics, Bernal Institute, University of Limerick, V94 T9PX Limerick, Ireland
| | - Stéphane Noselli
- grid.461605.0Université Côte d’Azur, CNRS, Inserm, Institut de Biologie Valrose, 06108 Nice, France
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3
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Jani J, Pappachan A. A review on quality control agents of protein translation - The role of Trans-editing proteins. Int J Biol Macromol 2022; 199:252-263. [PMID: 34995670 DOI: 10.1016/j.ijbiomac.2021.12.176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 12/18/2021] [Accepted: 12/27/2021] [Indexed: 11/16/2022]
Abstract
Translation of RNA to protein is a key feature of cellular life. The fidelity of this process mainly depends on the availability of correctly charged tRNAs. Different domains of tRNA synthetase (aaRS) maintain translation quality by ensuring the proper attachment of particular amino acid with respective tRNA, thus it establishes the rule of genetic code. However occasional errors by aaRS generate mischarged tRNAs, which can become lethal to the cells. Accurate protein synthesis necessitates hydrolysis of mischarged tRNAs. Various cis and trans-editing proteins are identified which recognize these mischarged products and correct them by hydrolysis. Trans-editing proteins are homologs of cis-editing domains of aaRS. The trans-editing proteins work in close association with aaRS, Ef-Tu, and ribosome to prevent global mistranslation and ensures correct charging of tRNA. In this review, we discuss the major trans-editing proteins and compared them with their cis-editing counterparts. We also discuss their structural features, biochemical activity and role in maintaining cellular protein homeostasis.
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Affiliation(s)
- Jaykumar Jani
- School of Life Sciences, Central University of Gujarat, Sector 30, Gandhinagar 382030, Gujarat, India
| | - Anju Pappachan
- School of Life Sciences, Central University of Gujarat, Sector 30, Gandhinagar 382030, Gujarat, India.
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4
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Zeng QY, Peng GX, Li G, Zhou JB, Zheng WQ, Xue MQ, Wang ED, Zhou XL. The G3-U70-independent tRNA recognition by human mitochondrial alanyl-tRNA synthetase. Nucleic Acids Res 2019; 47:3072-3085. [PMID: 30952159 PMCID: PMC6451123 DOI: 10.1093/nar/gkz078] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/28/2019] [Accepted: 01/31/2019] [Indexed: 11/13/2022] Open
Abstract
Alanyl-tRNA synthetases (AlaRSs) from three domains of life predominantly rely on a single wobble base pair, G3-U70, of tRNAAla as a major determinant. However, this base pair is divergent in human mitochondrial tRNAAla, but instead with a translocated G5-U68. How human mitochondrial AlaRS (hmtAlaRS) recognizes tRNAAla, in particular, in the acceptor stem region, remains unknown. In the present study, we found that hmtAlaRS is a monomer and recognizes mitochondrial tRNAAla in a G3-U70-independent manner, requiring several elements in the acceptor stem. In addition, we found that hmtAlaRS misactivates noncognate Gly and catalyzes strong transfer RNA (tRNA)-independent pre-transfer editing for Gly. A completely conserved residue outside of the editing active site, Arg663, likely functions as a tRNA translocation determinant to facilitate tRNA entry into the editing domain during editing. Finally, we investigated the effects of the severe infantile-onset cardiomyopathy-associated R592W mutation of hmtAlaRS on the canonical enzymatic activities of hmtAlaRS. Overall, our results provide fundamental information about tRNA recognition and deepen our understanding of translational quality control mechanisms by hmtAlaRS.
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Affiliation(s)
- Qi-Yu Zeng
- 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
| | - Gui-Xin Peng
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
| | - Guang Li
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
| | - Jing-Bo 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
| | - Wen-Qiang Zheng
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
| | - Mei-Qin Xue
- 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
| | - 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, 100 Haike 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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5
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Kuncha SK, Kruparani SP, Sankaranarayanan R. Chiral checkpoints during protein biosynthesis. J Biol Chem 2019; 294:16535-16548. [PMID: 31591268 DOI: 10.1074/jbc.rev119.008166] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Protein chains contain only l-amino acids, with the exception of the achiral glycine, making the chains homochiral. This homochirality is a prerequisite for proper protein folding and, hence, normal cellular function. The importance of d-amino acids as a component of the bacterial cell wall and their roles in neurotransmission in higher eukaryotes are well-established. However, the wider presence and the corresponding physiological roles of these specific amino acid stereoisomers have been appreciated only recently. Therefore, it is expected that enantiomeric fidelity has to be a key component of all of the steps in translation. Cells employ various molecular mechanisms for keeping d-amino acids away from the synthesis of nascent polypeptide chains. The major factors involved in this exclusion are aminoacyl-tRNA synthetases (aaRSs), elongation factor thermo-unstable (EF-Tu), the ribosome, and d-aminoacyl-tRNA deacylase (DTD). aaRS, EF-Tu, and the ribosome act as "chiral checkpoints" by preferentially binding to l-amino acids or l-aminoacyl-tRNAs, thereby excluding d-amino acids. Interestingly, DTD, which is conserved across all life forms, performs "chiral proofreading," as it removes d-amino acids erroneously added to tRNA. Here, we comprehensively review d-amino acids with respect to their occurrence and physiological roles, implications for chiral checkpoints required for translation fidelity, and potential use in synthetic biology.
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Affiliation(s)
- Santosh Kumar Kuncha
- Council of Scientific and Industrial Research (CSIR)-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, Telangana 500007, India.,Academy of Scientific and Innovative Research, CSIR-CCMB Campus, Hyderabad, Telangana 500007, India
| | - Shobha P Kruparani
- Council of Scientific and Industrial Research (CSIR)-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, Telangana 500007, India
| | - Rajan Sankaranarayanan
- Council of Scientific and Industrial Research (CSIR)-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, Telangana 500007, India
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6
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Substrate-assisted mechanism of catalytic hydrolysis of misaminoacylated tRNA required for protein synthesis fidelity. Biochem J 2019; 476:719-732. [PMID: 30718305 DOI: 10.1042/bcj20180910] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/28/2019] [Accepted: 02/01/2019] [Indexed: 11/17/2022]
Abstract
d-aminoacyl-tRNA-deacylase (DTD) prevents the incorporation of d-amino acids into proteins during translation by hydrolyzing the ester bond between mistakenly attached amino acids and tRNAs. Despite extensive study of this proofreading enzyme, the precise catalytic mechanism remains unknown. Here, a combination of biochemical and computational investigations has enabled the discovery of a new substrate-assisted mechanism of d-Tyr-tRNATyr hydrolysis by Thermus thermophilus DTD. Several functional elements of the substrate, misacylated tRNA, participate in the catalysis. During the hydrolytic reaction, the 2'-OH group of the А76 residue of d-Tyr-tRNATyr forms a hydrogen bond with a carbonyl group of the tyrosine residue, stabilizing the transition-state intermediate. Two water molecules participate in this reaction, attacking and assisting ones, resulting in a significant decrease in the activation energy of the rate-limiting step. The amino group of the d-Tyr aminoacyl moiety is unprotonated and serves as a general base, abstracting the proton from the assisting water molecule and forming a more nucleophilic ester-attacking species. Quantum chemical methodology was used to investigate the mechanism of hydrolysis. The DFT-calculated deacylation reaction is in full agreement with the experimental data. The Gibbs activation energies for the first and second steps were 10.52 and 1.05 kcal/mol, respectively, highlighting that the first step of the hydrolysis process is the rate-limiting step. Several amino acid residues of the enzyme participate in the coordination of the substrate and water molecules. Thus, the present work provides new insights into the proofreading details of misacylated tRNAs and can be extended to other systems important for translation fidelity.
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7
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Kuncha SK, Suma K, Pawar KI, Gogoi J, Routh SB, Pottabathini S, Kruparani SP, Sankaranarayanan R. A discriminator code-based DTD surveillance ensures faithful glycine delivery for protein biosynthesis in bacteria. eLife 2018; 7:38232. [PMID: 30091703 PMCID: PMC6097841 DOI: 10.7554/elife.38232] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/07/2018] [Indexed: 11/13/2022] Open
Abstract
D-aminoacyl-tRNA deacylase (DTD) acts on achiral glycine, in addition to D-amino acids, attached to tRNA. We have recently shown that this activity enables DTD to clear non-cognate Gly-tRNAAla with 1000-fold higher efficiency than its activity on Gly-tRNAGly, indicating tRNA-based modulation of DTD (Pawar et al., 2017). Here, we show that tRNA's discriminator base predominantly accounts for this activity difference and is the key to selection by DTD. Accordingly, the uracil discriminator base, serving as a negative determinant, prevents Gly-tRNAGly misediting by DTD and this protection is augmented by EF-Tu. Intriguingly, eukaryotic DTD has inverted discriminator base specificity and uses only G3•U70 for tRNAGly/Ala discrimination. Moreover, DTD prevents alanine-to-glycine misincorporation in proteins rather than only recycling mischarged tRNAAla. Overall, the study reveals the unique co-evolution of DTD and discriminator base, and suggests DTD's strong selection pressure on bacterial tRNAGlys to retain a pyrimidine discriminator code.
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Affiliation(s)
- Santosh Kumar Kuncha
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.,Academy of Scientific and Innovative Research, CSIR-CCMB Campus, Hyderabad, India
| | - Katta Suma
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | | - Jotin Gogoi
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
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8
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Rybak MY, Kovalenko OP, Tukalo MA. The Dual Role of the 2'-OH Group of A76 tRNA Tyr in the Prevention of d-tyrosine Mistranslation. J Mol Biol 2018; 430:2670-2676. [PMID: 29953888 DOI: 10.1016/j.jmb.2018.06.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 06/17/2018] [Accepted: 06/19/2018] [Indexed: 02/02/2023]
Abstract
Aminoacyl-tRNA-synthetases are crucial enzymes for initiation step of translation. Possessing editing activity, they protect living cells from misincorporation of non-cognate and non-proteinogenic amino acids into proteins. Tyrosyl-tRNA synthetase (TyrRS) does not have such editing properties, but it shares weak stereospecificity in recognition of d-/l-tyrosine (Tyr). Nevertheless, an additional enzyme, d-aminoacyl-tRNA-deacylase (DTD), exists to overcome these deficiencies. The precise catalytic role of hydroxyl groups of the tRNATyr A76 in the catalysis by TyrRS and DTD remained unknown. To address this issue, [32P]-labeled tRNATyr substrates have been tested in aminoacylation and deacylation assays. TyrRS demonstrates similar activity in charging the 2' and 3'-OH groups of A76 with l-Tyr. This synthetase can effectively use both OH groups as primary sites for aminoacylation with l-Tyr, but demonstrates severe preference toward 2'-OH, in charging with d-Tyr. In both cases, the catalysis is not substrate-assisted: neither the 2'-OH nor the 3'-OH group assists catalysis. In contrast, DTD catalyzes deacylation of d-Tyr-tRNATyr specifically from the 3'-OH group, while the 2'-OH assists in this hydrolysis.
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Affiliation(s)
- Mariia Yu Rybak
- Department of Protein Synthesis Enzymology, Institute of Molecular Biology and Genetics of the NAS of Ukraine, 150 Zabolotnogo Str., 03143 Kyiv, Ukraine.
| | - Oksana P Kovalenko
- Department of Protein Synthesis Enzymology, Institute of Molecular Biology and Genetics of the NAS of Ukraine, 150 Zabolotnogo Str., 03143 Kyiv, Ukraine
| | - Michael A Tukalo
- Department of Protein Synthesis Enzymology, Institute of Molecular Biology and Genetics of the NAS of Ukraine, 150 Zabolotnogo Str., 03143 Kyiv, Ukraine
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9
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Tian H, Zheng N, Li S, Zhang Y, Zhao S, Wen F, Wang J. Characterization of chiral amino acids from different milk origins using ultra-performance liquid chromatography coupled to ion-mobility mass spectrometry. Sci Rep 2017; 7:46289. [PMID: 28393862 PMCID: PMC5385494 DOI: 10.1038/srep46289] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 03/15/2017] [Indexed: 12/11/2022] Open
Abstract
Milk contains free amino acids (AAs) that play essential roles in maintaining the growth and health of infants, and D-AA isomers are increasingly being recognized as important signalling molecules. However, there are no studies of the different characteristics of chiral AA (C-AA) from different milk origins. Here, UPLC coupled to ion-mobility high-resolution MS (IM-HRMS) was employed to characterize 18 pairs of C-AAs in human, cow, yak, buffalo, goat, and camel milk. The results proved that milk origins can be differentiated based on the D- to L- AA ratio-based projection scores by principal component analysis. The present study gives a deeper understanding of the D- to L- AA ratio underlying the biological functions of different animal milks, and provide a new strategy for the study of AA metabolic pathways.
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Affiliation(s)
- He Tian
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Laboratory of Quality& Safety Risk Assessment for Dairy Products (Beijing), Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China
| | - Nan Zheng
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Laboratory of Quality& Safety Risk Assessment for Dairy Products (Beijing), Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China
| | - Songli Li
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Laboratory of Quality& Safety Risk Assessment for Dairy Products (Beijing), Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China
| | - Yangdong Zhang
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Laboratory of Quality& Safety Risk Assessment for Dairy Products (Beijing), Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China
| | - Shengguo Zhao
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Laboratory of Quality& Safety Risk Assessment for Dairy Products (Beijing), Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China
| | - Fang Wen
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Laboratory of Quality& Safety Risk Assessment for Dairy Products (Beijing), Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China
| | - Jiaqi Wang
- State Key Laboratory of Animal Nutrition, Ministry of Agriculture Laboratory of Quality& Safety Risk Assessment for Dairy Products (Beijing), Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, P.R. China
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10
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Pawar KI, Suma K, Seenivasan A, Kuncha SK, Routh SB, Kruparani SP, Sankaranarayanan R. Role of D-aminoacyl-tRNA deacylase beyond chiral proofreading as a cellular defense against glycine mischarging by AlaRS. eLife 2017; 6. [PMID: 28362257 PMCID: PMC5409826 DOI: 10.7554/elife.24001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/30/2017] [Indexed: 12/18/2022] Open
Abstract
Strict L-chiral rejection through Gly-cisPro motif during chiral proofreading underlies the inability of D-aminoacyl-tRNA deacylase (DTD) to discriminate between D-amino acids and achiral glycine. The consequent Gly-tRNAGly ‘misediting paradox’ is resolved by EF-Tu in the cell. Here, we show that DTD’s active site architecture can efficiently edit mischarged Gly-tRNAAla species four orders of magnitude more efficiently than even AlaRS, the only ubiquitous cellular checkpoint known for clearing the error. Also, DTD knockout in AlaRS editing-defective background causes pronounced toxicity in Escherichia coli even at low-glycine levels which is alleviated by alanine supplementation. We further demonstrate that DTD positively selects the universally invariant tRNAAla-specific G3•U70. Moreover, DTD’s activity on non-cognate Gly-tRNAAla is conserved across all bacteria and eukaryotes, suggesting DTD’s key cellular role as a glycine deacylator. Our study thus reveals a hitherto unknown function of DTD in cracking the universal mechanistic dilemma encountered by AlaRS, and its physiological importance. DOI:http://dx.doi.org/10.7554/eLife.24001.001 Proteins are made up of many different building blocks called amino acids, which are linked together in chains. The exact order of amino acids in a protein chain is important for the protein to work properly. When a cell makes proteins, molecules known as transfer ribonucleic acids (or tRNAs for short) bind to specific amino acids to guide them to the growing protein chains in the correct order. Most amino acids – except one called glycine – have two forms that are mirror images of one another, known as left-handed (L-amino acids) and right-handed (D-amino acids). However, only L-amino acids and glycine are used to make proteins. This is because of the presence of multiple quality control checkpoints in the cell that prevent D-amino acids from being involved. One such checkpoint is an enzyme called D-amino acid deacylase (DTD), which removes D-amino acids that are attached to tRNAs. Other enzymes are responsible for linking a particular amino acid to its correct tRNA. Along with mistaking D-amino acids for L-amino acids, these enzymes can also make errors when they have to distinguish between amino acids that are similar in shape and size. For example, the enzyme that attaches L-alanine to its tRNA can also mistakenly attach larger L-serine or smaller glycine to it instead. Previous research has shown that attaching L-serine to this tRNA can lead to neurodegeneration in mice, whereas attaching glycine does not seem to cause any harm. It is not clear why this is the case. Pawar et al. investigated how incorrectly attaching glycine or L-serine to the tRNA that usually binds to L-alanine affects a bacterium called Escherichia coli. The experiments show that, if the mistake is not corrected, glycine can be just as harmful to the cells as L-serine. The reason that glycine appears to be less of a problem is that the DTD enzyme is able to remove glycine, but not L-serine, from the tRNA. Further experiments show that DTD can play a similar role in a variety of organisms from bacteria to mammals. The findings of Pawar et al. extend the role of DTD beyond preventing D-amino acids from being incorporated into proteins. The next step is to understand the role of this enzyme in humans and other multicellular organisms, especially in the context of nerve cells, where it is present at high levels. DOI:http://dx.doi.org/10.7554/eLife.24001.002
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Affiliation(s)
| | - Katta Suma
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
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11
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Elongation Factor Tu Prevents Misediting of Gly-tRNA(Gly) Caused by the Design Behind the Chiral Proofreading Site of D-Aminoacyl-tRNA Deacylase. PLoS Biol 2016; 14:e1002465. [PMID: 27224426 PMCID: PMC4880308 DOI: 10.1371/journal.pbio.1002465] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/19/2016] [Indexed: 01/07/2023] Open
Abstract
D-aminoacyl-tRNA deacylase (DTD) removes D-amino acids mischarged on tRNAs and is thus implicated in enforcing homochirality in proteins. Previously, we proposed that selective capture of D-aminoacyl-tRNA by DTD's invariant, cross-subunit Gly-cisPro motif forms the mechanistic basis for its enantioselectivity. We now show, using nuclear magnetic resonance (NMR) spectroscopy-based binding studies followed by biochemical assays with both bacterial and eukaryotic systems, that DTD effectively misedits Gly-tRNAGly. High-resolution crystal structure reveals that the architecture of DTD's chiral proofreading site is completely porous to achiral glycine. Hence, L-chiral rejection is the only design principle on which DTD functions, unlike other chiral-specific enzymes such as D-amino acid oxidases, which are specific for D-enantiomers. Competition assays with elongation factor thermo unstable (EF-Tu) and DTD demonstrate that EF-Tu precludes Gly-tRNAGly misediting at normal cellular concentrations. However, even slightly higher DTD levels overcome this protection conferred by EF-Tu, thus resulting in significant depletion of Gly-tRNAGly. Our in vitro observations are substantiated by cell-based studies in Escherichia coli that show that overexpression of DTD causes cellular toxicity, which is largely rescued upon glycine supplementation. Furthermore, we provide direct evidence that DTD is an RNA-based catalyst, since it uses only the terminal 2'-OH of tRNA for catalysis without the involvement of protein side chains. The study therefore provides a unique paradigm of enzyme action for substrate selection/specificity by DTD, and thus explains the underlying cause of DTD's activity on Gly-tRNAGly. It also gives a molecular and functional basis for the necessity and the observed tight regulation of DTD levels, thereby preventing cellular toxicity due to misediting.
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Bhatt TK, Soni R, Sharma D. Recent Updates on DTD (D-Tyr-tRNA(Tyr) Deacylase): An Enzyme Essential for Fidelity and Quality of Protein Synthesis. Front Cell Dev Biol 2016; 4:32. [PMID: 27200345 PMCID: PMC4844752 DOI: 10.3389/fcell.2016.00032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 04/12/2016] [Indexed: 12/03/2022] Open
Abstract
During protein synthesis, there are several checkpoints in the cell to ensure that the information encoded within genetic material is decoded correctly. Charging of tRNA with its cognate amino acid is one of the important steps in protein synthesis and is carried out by aminoacyl-tRNA synthetase (aaRS) with great accuracy. However, due to presence of D-amino acids in the cell, sometimes aaRS charges tRNA with D-amino acids resulting in the hampering of protein translational process, which is lethal to the cell. Every species has some mechanism in order to prevent the formation of D-amino acid-tRNA complex, for instance DTD (D-Tyr-tRNA deacylase) is an enzyme responsible for the cleavage of ester bond formed between D-amino acid and tRNA leading to error free translation process. In this review, structure, function, and enzymatic mechanism of DTD are discussed. The role of DTD as a drug target is also considered.
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Affiliation(s)
- Tarun K Bhatt
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan Bandar sindri, India
| | - Rani Soni
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan Bandar sindri, India
| | - Drista Sharma
- Department of Biotechnology, School of Life Sciences, Central University of Rajasthan Bandar sindri, India
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Ma H, Liu N, Shi S, Wang S, Chen Y. Genetic incorporation of d-amino acids into green fluorescent protein based on polysubstrate specificity. RSC Adv 2015. [DOI: 10.1039/c5ra02289d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A number of d-amino acids were genetically incorporated into green fluorescent protein, and the GFPuv mutant containing d-phenylalanine in the fluorophore at residue 66 was characterized.
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Affiliation(s)
- Hairong Ma
- State Key Laboratory of Natural Medicines and Laboratory of Chemical Biology
- China Pharmaceutical University
- Nanjing
- People’s Republic of China
| | - Nan Liu
- State Key Laboratory of Natural Medicines and Laboratory of Chemical Biology
- China Pharmaceutical University
- Nanjing
- People’s Republic of China
| | - Shaobo Shi
- State Key Laboratory of Natural Medicines and Laboratory of Chemical Biology
- China Pharmaceutical University
- Nanjing
- People’s Republic of China
| | - Shuzhen Wang
- State Key Laboratory of Natural Medicines and Laboratory of Chemical Biology
- China Pharmaceutical University
- Nanjing
- People’s Republic of China
| | - Yijun Chen
- State Key Laboratory of Natural Medicines and Laboratory of Chemical Biology
- China Pharmaceutical University
- Nanjing
- People’s Republic of China
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Datt M, Sharma A. Novel and unique domains in aminoacyl-tRNA synthetases from human fungal pathogens Aspergillus niger, Candida albicans and Cryptococcus neoformans. BMC Genomics 2014; 15:1069. [PMID: 25479903 PMCID: PMC4301749 DOI: 10.1186/1471-2164-15-1069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 11/20/2014] [Indexed: 12/15/2022] Open
Abstract
Background Some species of fungi can cause serious human diseases, particularly to immuno-compromised individuals. Opportunistic fungal infections are a leading cause of mortality, and present an emerging challenge that requires development of new and effective therapeutics. Aminoacyl-tRNA synthetases (aaRSs) are indispensable components of cellular protein translation machinery and can be targeted for discovery of novel anti-fungal agents. Results Validation of aaRSs as potential drug targets in pathogenic microbes prompted us to investigate the genomic distribution of aaRSs within three fungi that infect humans – A. niger, C. albicans and C. neoformans. Hidden Markov Models were built for aaRSs and related proteins to search for homologues in these fungal genomes. Here, we provide a detailed and comprehensive annotation for 3 fungal genome aaRSs and their associated proteins. We delineate predicted localizations, subdomain architectures and prevalence of unusual motifs within these aaRSs. Several fungal aaRSs have unique domain appendages of unknown function e.g. A. niger AsxRS and C. neoformans TyrRS have additional domains that are absent from human homologs. Conclusions Detailed comparisons of fungal aaRSs with human homologs suggest key differences that could be exploited for specific drug targeting. Our cataloging and structural analyses provide a comprehensive foundation for experimentally dissecting fungal aaRSs that may enable development of new anti-fungal agents. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1069) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Amit Sharma
- Structural and Computational Biology group, International Center for Genetic Engineering and Biotechnology (ICGEB), New Delhi 110067, India.
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Ahmad S, Routh SB, Kamarthapu V, Chalissery J, Muthukumar S, Hussain T, Kruparani SP, Deshmukh MV, Sankaranarayanan R. Mechanism of chiral proofreading during translation of the genetic code. eLife 2013; 2:e01519. [PMID: 24302572 PMCID: PMC3845328 DOI: 10.7554/elife.01519] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The biological macromolecular world is homochiral and effective enforcement and perpetuation of this homochirality is essential for cell survival. In this study, we present the mechanistic basis of a configuration-specific enzyme that selectively removes D-amino acids erroneously coupled to tRNAs. The crystal structure of dimeric D-aminoacyl-tRNA deacylase (DTD) from Plasmodium falciparum in complex with a substrate-mimicking analog shows how it uses an invariant ‘cross-subunit’ Gly-cisPro dipeptide to capture the chiral centre of incoming D-aminoacyl-tRNA. While no protein residues are directly involved in catalysis, the unique side chain-independent mode of substrate recognition provides a clear explanation for DTD’s ability to act on multiple D-amino acids. The strict chiral specificity elegantly explains how the enriched cellular pool of L-aminoacyl-tRNAs escapes this proofreading step. The study thus provides insights into a fundamental enantioselection process and elucidates a chiral enforcement mechanism with a crucial role in preventing D-amino acid infiltration during the evolution of translational apparatus. DOI:http://dx.doi.org/10.7554/eLife.01519.001 Amino acids are ‘chiral’ molecules that come in two different forms, called D and L, which are mirror images of each other, similar to how our left and right hands are mirror images of each other. However, only one of these forms is used to make proteins: the more abundant L-amino acids are linked together to make proteins, whereas the scarcer D-amino acids are not. This ‘homochirality’ is common to all life on Earth. The molecular machinery inside cells that manufactures proteins involves many enzymes that carry out different tasks. Among these is an enzyme called DTD (short for D-aminoacyl-tRNA deacylase), which prevents D-amino acids being incorporated into proteins. To do this, DTD must be able to recognise and remove the D forms of many different amino acids before they are taken to the growing protein by transfer RNA molecules. However, the details of this process are not fully understood. To investigate this mechanism, Ahmad et al. made crystals of the DTD enzyme in complex with a molecule that mimics a D-amino acid attached to a transfer RNA molecule. By studying this structure at a high resolution, Ahmad et al. were able to identify how the active site of DTD can specifically accommodate the ‘chiral centre’ of a complex made of a D-amino acid and a transfer RNA molecule. DTD is able to recognize D-amino acids because of a critical dipeptide that is inserted from one subunit of the DTD into the active site of another subunit of the enzyme. The effect of this dipeptide is to generate a binding pocket that is a perfect fit for the chiral centre of a complex that contains a D-amino acid and a transfer RNA molecule. Moreover, this pocket specifically excludes complexes that contain an L-amino acid. The crucial parts of DTD that form the binding pocket are highly conserved—that is, they are the same in a wide variety of organisms, from bacteria to mammals. This conservation suggests that DTD is crucial for ensuring homochirality throughout all forms of life. Intriguingly, DTD is particularly highly expressed in neurons which are abundant in D-amino acids: this indicates that the DTD enzyme has an important physiological role, which will certainly be the focus of future work. DOI:http://dx.doi.org/10.7554/eLife.01519.002
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Affiliation(s)
- Sadeem Ahmad
- Structural Biology Laboratory, Centre for Cellular and Molecular Biology, Council for Scientific and Industrial Research, Hyderabad, India
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Vondenhoff GH, Pugach K, Gadakh B, Carlier L, Rozenski J, Froeyen M, Severinov K, Van Aerschot A. N-alkylated aminoacyl sulfamoyladenosines as potential inhibitors of aminoacylation reactions and microcin C analogues containing D-amino acids. PLoS One 2013; 8:e79234. [PMID: 24223911 PMCID: PMC3817062 DOI: 10.1371/journal.pone.0079234] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 09/19/2013] [Indexed: 11/18/2022] Open
Abstract
Microcin C analogues were recently envisaged as important compounds for the development of novel antibiotics. Two issues that may pose problems to these potential antibiotics are possible acquisition of resistance through acetylation and in vivo instability of the peptide chain. N-methylated aminoacyl sulfamoyladenosines were synthesized to investigate their potential as aminoacyl tRNA synthetase inhibitors and to establish whether these N-alkylated analogues would escape the natural inactivation mechanism via acetylation of the alpha amine. It was shown however, that these compounds are not able to effectively inhibit their respective aminoacyl tRNA synthetase. In addition, we showed that (D)-aspartyl-sulfamoyladenosine (i.e. with a (D)-configuration for the aspartyl moiety), is a potent inhibitor of aspartyl tRNA synthetase. However, we also showed that the inhibitory effect of (D)- aspartyl-sulfamoyladenosine is relatively short-lasting. Microcin C analogues with (D)-amino acids throughout from positions two to six proved inactive. They were shown to be resistant against metabolism by the different peptidases and therefore not able to release the active moiety. This observation could not be reversed by incorporation of (L)-amino acids at position six, showing that none of the available peptidases exhibit endopeptidase activity.
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Affiliation(s)
- Gaston H. Vondenhoff
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Ksenia Pugach
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Bharat Gadakh
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Laurence Carlier
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Jef Rozenski
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Mathy Froeyen
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
| | - Konstantin Severinov
- Department of Molecular Biology and Biochemistry Waksman Institute, Rutgers, the State University, Piscataway, New Jersey, United States of America
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Arthur Van Aerschot
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Leuven, Belgium
- * E-mail:
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Friedman M, Levin CE. Nutritional and medicinal aspects of D-amino acids. Amino Acids 2011; 42:1553-82. [PMID: 21519915 DOI: 10.1007/s00726-011-0915-1] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 04/06/2011] [Indexed: 02/07/2023]
Abstract
This paper reviews and interprets a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid such as L-lysine (L-Lys), L-methionine (L-Met), L-phenylalanine (L-Phe), and L-tryptophan (L-Trp) as well as the semi-essential amino acids L-cysteine (L-Cys) and L-tyrosine (L-Tyr). The results show wide-ranging variations in the biological utilization of test substances. The method is generally applicable to the determination of the biological utilization and safety of any amino acid derivative as a potential nutritional source of the corresponding L-amino acid. Because the organism is forced to use the D-amino acid or amino acid derivative as the sole source of the essential or semi-essential amino acid being replaced, and because a free amino acid diet allows better control of composition, the use of all-amino-acid diets for such determinations may be preferable to protein-based diets. Also covered are brief summaries of the widely scattered literature on dietary and pharmacological aspects of 27 individual D-amino acids, D-peptides, and isomeric amino acid derivatives and suggested research needs in each of these areas. The described results provide a valuable record and resource for further progress on the multifaceted aspects of D-amino acids in food and biological samples.
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Affiliation(s)
- Mendel Friedman
- Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA.
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Liu W, Liu C, Zhu JX, Li AH, Zhao ZQ, Yin B, Peng XZ. D-Tyr-tRNA(Tyr) deacylase, a new role in Alzheimer's-associated disease in SAMP8 mice. ACTA ACUST UNITED AC 2010; 25:90-4. [PMID: 20598230 DOI: 10.1016/s1001-9294(10)60028-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE To assess the expression level of D-Tyr-tRNA(Tyr) deacylase (DTD) in SAMP8 mice and speculate the function of DTD in disorders associated with Alzheimer's disease (AD). METHODS Altogether 12 SAMP8 mice and 12 SAMR1 mice were used in this study. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were performed to detect the mRNA and protein levels of DTD in the mice. Purified DTD protein was injected into lateral ventricle to investigate the function of DTD in SAMP mice. The behavior of the mice was tested by using a Step-through Test System. RESULTS Both mRNA and protein levels of DTD were found to be significantly lower in SAMP8 mice compared with those in SAMR1 mice (P<0.05). In vivo injection of DTD protein did not lead to an obvious change in behavior of SAM mice. CONCLUSIONS DTD might function in the process of AD-associated pathology and could possibly participate in physiology process in a long-term manner to orchestrate with other regulators in order to maintain the balance of organism.
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Affiliation(s)
- Wei Liu
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China
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Friedman M. Origin, Microbiology, Nutrition, and Pharmacology of D-Amino Acids. Chem Biodivers 2010; 7:1491-530. [DOI: 10.1002/cbdv.200900225] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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The DNA unwinding element binding protein DUE-B interacts with Cdc45 in preinitiation complex formation. Mol Cell Biol 2010; 30:1495-507. [PMID: 20065034 DOI: 10.1128/mcb.00710-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Template unwinding during DNA replication initiation requires the loading of the MCM helicase activator Cdc45 at replication origins. We show that Cdc45 interacts with the DNA unwinding element (DUE) binding protein DUE-B and that these proteins localize to the DUEs of active replication origins. DUE-B and Cdc45 are not bound at the inactive c-myc replicator in the absence of a functional DUE or at the recently identified ataxin 10 (ATX10) origin, which is silent before disease-related (ATTCT)(n) repeat length expansion of its DUE sequence, despite the presence of the origin recognition complex (ORC) and MCM proteins at these origins. Addition of a heterologous DUE to the ectopic c-myc origin, or expansion of the ATX10 DUE, leads to origin activation, DUE-B binding, and Cdc45 binding. DUE-B, Cdc45, and topoisomerase IIbeta binding protein 1 (TopBP1) form complexes in cell extracts and when expressed from baculovirus vectors. During replication in Xenopus egg extracts, DUE-B and Cdc45 bind to chromatin with similar kinetics, and DUE-B immunodepletion blocks replication and the loading of Cdc45 and a fraction of TopBP1. The coordinated binding of DUE-B and Cdc45 to origins and the physical interactions of DUE-B, Cdc45, and TopBP1 suggest that complexes of these proteins are necessary for replication initiation.
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Bhatt TK, Yogavel M, Wydau S, Berwal R, Sharma A. Ligand-bound structures provide atomic snapshots for the catalytic mechanism of D-amino acid deacylase. J Biol Chem 2009; 285:5917-30. [PMID: 20007323 PMCID: PMC2820817 DOI: 10.1074/jbc.m109.038562] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
d-tyrosyl-tRNATyr deacylase (DTD) is an editing enzyme that removes d-amino acids from mischarged tRNAs. We describe an in-depth analysis of the malaria parasite Plasmodium falciparum DTD here. Our data provide structural insights into DTD complexes with adenosine and d-amino acids. Bound adenosine is proximal to the DTD catalysis site, and it represents the authentic terminal adenosine of charged tRNA. DTD-bound d-amino acids cluster at three different subsites within the overall active site pocket. These subsites, called transition, active, and exit subsites allow docking, re-orientation, chiral selection, catalysis, and exit of the free d-amino acid from DTD. Our studies reveal variable modes of d-amino acid recognition by DTDs, suggesting an inherent plasticity that can accommodate all d- amino acids. An in-depth analysis of native, ADP-bound, and d- amino acid-complexed DTD structures provide the first atomic snapshots of ligand recognition and subsequent catalysis by this enzyme family. We have mapped sites for the deacylation reaction and mark possible routes for entry and egress of all substrates and products. We have also performed structure-based inhibitor discovery and tested lead compounds against the malaria parasite P. falciparum using growth inhibition assays. Our studies provide a comprehensive structural basis for the catalytic mechanism of DTD enzymes and have implications for inhibition of this enzyme in P. falciparum as a route to inhibiting the parasite.
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Affiliation(s)
- Tarun Kumar Bhatt
- Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Road, New Delhi, 110067, India
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Wydau S, van der Rest G, Aubard C, Plateau P, Blanquet S. Widespread distribution of cell defense against D-aminoacyl-tRNAs. J Biol Chem 2009; 284:14096-104. [PMID: 19332551 DOI: 10.1074/jbc.m808173200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several l-aminoacyl-tRNA synthetases can transfer a d-amino acid onto their cognate tRNA(s). This harmful reaction is counteracted by the enzyme d-aminoacyl-tRNA deacylase. Two distinct deacylases were already identified in bacteria (DTD1) and in archaea (DTD2), respectively. Evidence was given that DTD1 homologs also exist in nearly all eukaryotes, whereas DTD2 homologs occur in plants. On the other hand, several bacteria, including most cyanobacteria, lack genes encoding a DTD1 homolog. Here we show that Synechocystis sp. PCC6803 produces a third type of deacylase (DTD3). Inactivation of the corresponding gene (dtd3) renders the growth of Synechocystis sp. hypersensitive to the presence of d-tyrosine. Based on the available genomes, DTD3-like proteins are predicted to occur in all cyanobacteria. Moreover, one or several dtd3-like genes can be recognized in all cellular types, arguing in favor of the nearubiquity of an enzymatic function involved in the defense of translational systems against invasion by d-amino acids.
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Affiliation(s)
- Sandra Wydau
- Laboratoire de Biochimie and Laboratoire des Mécanismes Réactionnels, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France
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