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Narasimha SM, Malpani T, Mohite OS, Nath JS, Raman K. Understanding flux switching in metabolic networks through an analysis of synthetic lethals. NPJ Syst Biol Appl 2024; 10:104. [PMID: 39289347 PMCID: PMC11408705 DOI: 10.1038/s41540-024-00426-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 08/17/2024] [Indexed: 09/19/2024] Open
Abstract
Biological systems are robust and redundant. The redundancy can manifest as alternative metabolic pathways. Synthetic double lethals are pairs of reactions that, when deleted simultaneously, abrogate cell growth. However, removing one reaction allows the rerouting of metabolites through alternative pathways. Little is known about these hidden linkages between pathways. Understanding them in the context of pathogens is useful for therapeutic innovations. We propose a constraint-based optimisation approach to identify inter-dependencies between metabolic pathways. It minimises rerouting between two reaction deletions, corresponding to a synthetic lethal pair, and outputs the set of reactions vital for metabolic rewiring, known as the synthetic lethal cluster. We depict the results for different pathogens and show that the reactions span across metabolic modules, illustrating the complexity of metabolism. Finally, we demonstrate how the two classes of synthetic lethals play a role in metabolic networks and influence the different properties of a synthetic lethal cluster.
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Affiliation(s)
- Sowmya Manojna Narasimha
- Centre for Integrative Biology and Systems mEdicine (IBSE), Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India
- Department of Biotechnology, Bhupat Jyoti Mehta School of Biosciences, Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India
- Neuroscience Graduate Program, University of California San Diego, San Diego, CA, 92092, USA
| | - Tanisha Malpani
- Centre for Integrative Biology and Systems mEdicine (IBSE), Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India
- Department of Biotechnology, Bhupat Jyoti Mehta School of Biosciences, Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India
| | - Omkar S Mohite
- Centre for Integrative Biology and Systems mEdicine (IBSE), Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India
- Department of Biotechnology, Bhupat Jyoti Mehta School of Biosciences, Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - J Saketha Nath
- Department of Computer Science and Engineering, Indian Institute of Technology (IIT) Hyderabad, Hyderabad, 502 284, India
| | - Karthik Raman
- Centre for Integrative Biology and Systems mEdicine (IBSE), Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India.
- Department of Biotechnology, Bhupat Jyoti Mehta School of Biosciences, Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India.
- Department of Data Science and AI, Wadhwani School of Data Science and AI (WSAI), Indian Institute of Technology (IIT) Madras, Chennai, 600 036, India.
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Tsukimi T, Obana N, Shigemori S, Arakawa K, Miyauchi E, Yang J, Song I, Ashino Y, Wakayama M, Soga T, Tomita M, Ohno H, Mori H, Fukuda S. Genetic mutation in Escherichia coli genome during adaptation to the murine intestine is optimized for the host diet. mSystems 2024; 9:e0112323. [PMID: 38205998 PMCID: PMC10878103 DOI: 10.1128/msystems.01123-23] [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: 10/23/2023] [Accepted: 11/15/2023] [Indexed: 01/12/2024] Open
Abstract
Mammalian gut microbes colonize the intestinal tract of their host and adapt to establish a microbial ecosystem. The host diet changes the nutrient profile of the intestine and has a high impact on microbiota composition. Genetic mutations in Escherichia coli, a prevalent species in the human gut, allow for adaptation to the mammalian intestine, as reported in previous studies. However, the extent of colonization fitness in the intestine elevated by genetic mutation and the effects of diet change on these mutations in E. coli are still poorly known. Here, we show that notable mutations in sugar metabolism-related genes (gatC, araC, and malI) were detected in the E. coli K-12 genome just 2 weeks after colonization in the germ-free mouse intestine. In addition to elevated fitness by deletion of gatC, as previously reported, deletion of araC and malI also elevated E. coli fitness in the murine intestine in a host diet-dependent manner. In vitro cultures of medium containing nutrients abundant in the intestine (e.g., galactose, N-acetylglucosamine, and asparagine) also showed increased E. coli fitness after deletion of the genes-of-interest associated with their metabolism. Furthermore, the host diet was found to influence the developmental trajectory of gene mutations in E. coli. Taken together, we suggest that genetic mutations in E. coli are selected in response to the intestinal environment, which facilitates efficient utilization of nutrients abundant in the intestine under laboratory conditions. Our study offers some insight into the possible adaptation mechanisms of gut microbes.IMPORTANCEThe gut microbiota is closely associated with human health and is greatly impacted by the host diet. Bacteria such as Escherichia coli live in the gut all throughout the life of a human host and adapt to the intestinal environment. Adaptive mutations in E. coli are reported to enhance fitness in the mammalian intestine, but to what extent is still poorly known. It is also unknown whether the host diet affects what genes are mutated and to what extent fitness is affected. This study suggests that genetic mutations in the E. coli K-12 strain are selected in response to the intestinal environment and facilitate efficient utilization of abundant nutrients in the germ-free mouse intestine. Our study provides a better understanding of these intestinal adaptation mechanisms of gut microbes.
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Affiliation(s)
- Tomoya Tsukimi
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
| | - Nozomu Obana
- Transborder Medical Research Center, Institute of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Suguru Shigemori
- Transborder Medical Research Center, Institute of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Kazuharu Arakawa
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
- Faculty of Environment and Information Studies, Keio University, Fujisawa, Japan
| | - Eiji Miyauchi
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Jiayue Yang
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
| | - Isaiah Song
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
| | - Yujin Ashino
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
| | - Masataka Wakayama
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
- Faculty of Environment and Information Studies, Keio University, Fujisawa, Japan
| | - Masaru Tomita
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
- Faculty of Environment and Information Studies, Keio University, Fujisawa, Japan
| | - Hiroshi Ohno
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Hirotada Mori
- Graduate School of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
- Institute of Animal Sciences, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Shinji Fukuda
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
- Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, Japan
- Transborder Medical Research Center, Institute of Medicine, University of Tsukuba, Tsukuba, Japan
- Gut Environmental Design Group, Kanagawa Institute of Industrial Science and Technology, Kawasaki, Japan
- Laboratory for Regenerative Microbiology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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Park J, Lee SM, Ebrahim A, Scott-Nevros Z, Kim J, Yang L, Sastry A, Seo S, Palsson BO, Kim D. Model-driven experimental design workflow expands understanding of regulatory role of Nac in Escherichia coli. NAR Genom Bioinform 2023; 5:lqad006. [PMID: 36685725 PMCID: PMC9853098 DOI: 10.1093/nargab/lqad006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 12/07/2022] [Accepted: 01/09/2023] [Indexed: 01/22/2023] Open
Abstract
The establishment of experimental conditions for transcriptional regulator network (TRN) reconstruction in bacteria continues to be impeded by the limited knowledge of activating conditions for transcription factors (TFs). Here, we present a novel genome-scale model-driven workflow for designing experimental conditions, which optimally activate specific TFs. Our model-driven workflow was applied to elucidate transcriptional regulation under nitrogen limitation by Nac and NtrC, in Escherichia coli. We comprehensively predict alternative nitrogen sources, including cytosine and cytidine, which trigger differential activation of Nac using a model-driven workflow. In accordance with the prediction, genome-wide measurements with ChIP-exo and RNA-seq were performed. Integrative data analysis reveals that the Nac and NtrC regulons consist of 97 and 43 genes under alternative nitrogen conditions, respectively. Functional analysis of Nac at the transcriptional level showed that Nac directly down-regulates amino acid biosynthesis and restores expression of tricarboxylic acid (TCA) cycle genes to alleviate nitrogen-limiting stress. We also demonstrate that both TFs coherently modulate α-ketoglutarate accumulation stress due to nitrogen limitation by co-activating amino acid and diamine degradation pathways. A systems-biology approach provided a detailed and quantitative understanding of both TF's roles and how nitrogen and carbon metabolic networks respond complementarily to nitrogen-limiting stress.
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Affiliation(s)
- Joon Young Park
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Sang-Mok Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Ali Ebrahim
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Zoe K Scott-Nevros
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jaehyung Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Laurence Yang
- Department of Chemical Engineering, Queen's University, Kingston, Canada
| | - Anand Sastry
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sang Woo Seo
- School of Chemical and Biological Engineering, and Interdisciplinary Program in Bioengineering, and Institute of Chemical Processes, and Bio-MAX Institute, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
- The Novo Nordisk Foundation Center for Biosustainability, Danish Technical University, 6 Kogle Alle, Hørsholm, Denmark
| | - Donghyuk Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
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Yang CI, Zhu Z, Jones JJ, Lomenick B, Chou TF, Shan SO. System-wide analyses reveal essential roles of N-terminal protein modification in bacterial membrane integrity. iScience 2022; 25:104756. [PMID: 35942092 PMCID: PMC9356101 DOI: 10.1016/j.isci.2022.104756] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/20/2022] [Accepted: 07/07/2022] [Indexed: 11/18/2022] Open
Abstract
The removal of the N-terminal formyl group on nascent proteins by peptide deformylase (PDF) is the most prevalent protein modification in bacteria. PDF is a critical target of antibiotic development; however, its role in bacterial physiology remains a long-standing question. This work used the time-resolved analyses of the Escherichia coli translatome and proteome to investigate the consequences of PDF inhibition. Loss of PDF activity rapidly induces cellular stress responses, especially those associated with protein misfolding and membrane defects, followed by a global down-regulation of metabolic pathways. Rapid membrane hyperpolarization and impaired membrane integrity were observed shortly after PDF inhibition, suggesting that the plasma membrane disruption is the most immediate and primary consequence of formyl group retention on nascent proteins. This work resolves the physiological function of a ubiquitous protein modification and uncovers its crucial role in maintaining the structure and function of the bacterial membrane.
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Affiliation(s)
- Chien-I Yang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Zikun Zhu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Jeffrey J. Jones
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA, USA
| | - Brett Lomenick
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA, USA
| | - Tsui-Fen Chou
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA, USA
| | - Shu-ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
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Luo W, Xu J, Chen H, Zhang H, Yang P, Yu X. Synthesis of L-asparagine Catalyzed by a Novel Asparagine Synthase Coupled With an ATP Regeneration System. Front Bioeng Biotechnol 2021; 9:747404. [PMID: 34631686 PMCID: PMC8495130 DOI: 10.3389/fbioe.2021.747404] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 08/09/2021] [Indexed: 11/23/2022] Open
Abstract
Compared with low-yield extraction from plants and environmentally unfriendly chemical synthesis, biocatalysis by asparagine synthetase (AS) for preparation of L-asparagine (L-Asn) has become a potential synthetic method. However, low enzyme activity of AS and high cost of ATP in this reaction restricts the large-scale preparation of L-Asn by biocatalysis. In this study, gene mining strategy was used to search for novel AS with high enzyme activity by expressing them in Escherichia coli BL21 (DE3) or Bacillus subtilis WB600. The obtained LsaAS-A was determined for its enzymatic properties and used for subsequent preparation of L-Asn. In order to reduce the use of ATP, a class III polyphosphate kinase 2 from Deinococcus ficus (DfiPPK2-Ⅲ) was cloned and expressed in E. coli BL21 (DE3), Rosetta (DE3) or RosettagamiB (DE3) for ATP regeneration. A coupling reaction system including whole cells expressing LsaAS-A and DfiPPK2-Ⅲ was constructed to prepare L-Asn from L-aspartic acid (L-Asp). Batch catalytic experiments showed that sodium hexametaphosphate (>60 mmol L−1) and L-Asp (>100 mmol L−1) could inhibit the synthesis of L-Asn. Under fed-batch mode, L-Asn yield reached 90.15% with twice feeding of sodium hexametaphosphate. A final concentration of 218.26 mmol L−1 L-Asn with a yield of 64.19% was obtained when L-Asp and sodium hexametaphosphate were fed simultaneously.
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Affiliation(s)
- Wei Luo
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Jinglong Xu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Huiying Chen
- College of Chemistry and Bioengineering, Guilin University of Technology, Guilin, China
| | - Huili Zhang
- College of Life Sciences, University of Shihezi, Shihezi, China
| | - Peilong Yang
- Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Institute of Feed Research of CAAS, Beijing, China
| | - Xiaobin Yu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
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Zhang S, Feng HC, Liu JL. ASNS disruption shortens CTPS cytoophidia in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2021; 11:6080684. [PMID: 33561249 PMCID: PMC8022725 DOI: 10.1093/g3journal/jkaa060] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 12/09/2020] [Indexed: 02/07/2023]
Abstract
Asparagine synthetase (ASNS) and CTP synthase (CTPS) are two metabolic enzymes that catalyze the biosynthesis of asparagine and CTP, respectively. Both CTPS and ASNS have been identified to form cytoophidia in Saccharomyces cerevisiae. Glutamine is a common substrate for both these enzymes, and they play an important role in glutamine homeostasis. Here, we find that the ASNS cytoophidia are shorter than the CTPS cytoophidia, and that disruption of ASNS shortens the length of CTPS cytoophidia. However, the deletion of CTPS has no effect on the formation and length of ASNS cytoophidia, or on the ASNS protein level. We also find that Asn1 overexpression induces the formation of a multi-dot structure in diauxic phase which suggests that the increased protein level may trigger cytoophidia formation. Collectively, our results reveal a connection between ASNS cytoophidia and CTPS cytoophidia.
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Affiliation(s)
- Shanshan Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,University of Chinese Academy of Sciences, Beijing, 100049, China.,Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Han-Chao Feng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Ji-Long Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
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Integration of the pSLT Plasmid into the Salmonella Chromosome Results in a Temperature-Sensitive Growth Defect Due to Aberrant DNA Replication. J Bacteriol 2020; 202:JB.00380-20. [PMID: 32747428 DOI: 10.1128/jb.00380-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 07/16/2020] [Indexed: 11/20/2022] Open
Abstract
A mutant of Salmonella enterica serovar Typhimurium was isolated that simultaneously affected two metabolic pathways as follows: NAD metabolism and DNA repair. The mutant was isolated as resistant to a nicotinamide analog and as temperature-sensitive for growth on minimal glucose medium. In this mutant, Salmonella's 94-kb virulence plasmid pSLT had recombined into the chromosome upstream of the NAD salvage pathway gene pncA This insertion blocked most transcription of pncA, which reduced uptake of the nicotinamide analog. The pSLT insertion mutant also exhibited phenotypes associated with induction of the SOS DNA repair system, including an increase in filamentous cells, higher exonuclease III and catalase activities, and derepression of SOS gene expression. Genome sequencing revealed increased read coverage extending out from the site of pSLT insertion. The two pSLT replication origins are likely initiating replication of the chromosome near the normal replication terminus. Too much replication initiation at the wrong site is probably causing the observed growth defects. Accordingly, deletion of both pSLT replication origins restored growth at higher temperatures.IMPORTANCE In studies that insert a second replication origin into the chromosome, both origins are typically active at the same time. In contrast, the integrated pSLT plasmid initiated replication in stationary phase after normal chromosomal replication had finished. The gradient in read coverage extending out from a single site could be a simple but powerful tool for studying replication and detecting chromosomal rearrangements. This technique may be of particular value when a genome has been sequenced for the first time to verify correct assembly.
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In-solution behavior and protective potential of asparagine synthetase A from Trypanosoma cruzi. Mol Biochem Parasitol 2019; 230:1-7. [PMID: 30885794 DOI: 10.1016/j.molbiopara.2019.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 03/11/2019] [Accepted: 03/11/2019] [Indexed: 11/24/2022]
Abstract
l-Asparagine synthetase (AS) acts in asparagine formation and can be classified into two families: AS-A or AS-B. AS-A is mainly found in prokaryotes and can synthetize asparagine from ammonia. Distinct from other eukaryotes, Trypanosoma cruzi produces an AS-A. AS-A from Trypanosoma cruzi (Tc-AS-A) differs from prokaryotic AS-A due to its ability to catalyze asparagine synthesis using both glutamine and ammonia as nitrogen sources. Regarding these peculiarities, this work uses several biophysical techniques to provide data concerning the Tc-AS-A in-solution behavior. Tc-AS-A was produced as a recombinant and purified by three chromatography steps. Circular dichroism, dynamic light scattering, and analytical size exclusion chromatography showed that Tc-AS-A has the same fold and quaternary arrangement of prokaryotic AS-A. Despite the tendency of protein to aggregate, stable dimers were obtained when solubilization occurred at pH ≤ 7.0. We also demonstrate the protective efficacy against T. cruzi infection in mice immunized with Tc-AS-A. Our results indicate that immunization with Tc-AS-A might confer partial protection to infective forms of T. cruzi in this particular model.
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Lalaouna D, Eyraud A, Devinck A, Prévost K, Massé E. GcvB small RNA uses two distinct seed regions to regulate an extensive targetome. Mol Microbiol 2018; 111:473-486. [PMID: 30447071 DOI: 10.1111/mmi.14168] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2018] [Indexed: 01/01/2023]
Abstract
GcvB small RNA is described as post-transcriptional regulator of 1-2% of all mRNAs in Escherichia coli and Salmonella Typhimurium. At least 24 GcvB:mRNA interactions have been validated in vivo, establishing the largest characterized sRNA targetome. By performing MS2-affinity purification coupled with RNA sequencing (MAPS) technology, we identified seven additional mRNAs negatively regulated by GcvB in E. coli. Contrary to the vast majority of previously known targets, which pair to the well-conserved GcvB R1 region, we validated four mRNAs targeted by GcvB R3 region. This indicates that base-pairing through R3 seed sequence seems relatively common. We also noticed unusual GcvB pairing sites in the coding sequence of two target mRNAs. One of these target mRNAs has a pairing site displaying a unique ACA motif, suggesting that GcvB could hijack a translational enhancer element. The second target mRNA is likely regulated via an active RNase E-mediated mRNA degradation mechanism. Remarkably, we confirmed the importance of the sRNA sponge SroC in the fine-tuning control of GcvB activity in function of growth conditions such as growth phase and nutrient availability.
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Affiliation(s)
- David Lalaouna
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Alex Eyraud
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Aurélie Devinck
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Karine Prévost
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Eric Massé
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
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Jakočiūnė D, Herrero-Fresno A, Jelsbak L, Olsen JE. Highly expressed amino acid biosynthesis genes revealed by global gene expression analysis of Salmonella enterica serovar Enteritidis during growth in whole egg are not essential for this growth. Int J Food Microbiol 2016; 224:40-6. [DOI: 10.1016/j.ijfoodmicro.2016.02.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/12/2016] [Accepted: 02/21/2016] [Indexed: 01/17/2023]
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Faria J, Loureiro I, Santarém N, Macedo-Ribeiro S, Tavares J, Cordeiro-da-Silva A. Leishmania infantum Asparagine Synthetase A Is Dispensable for Parasites Survival and Infectivity. PLoS Negl Trop Dis 2016; 10:e0004365. [PMID: 26771178 PMCID: PMC4714757 DOI: 10.1371/journal.pntd.0004365] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/15/2015] [Indexed: 11/19/2022] Open
Abstract
A growing interest in asparagine (Asn) metabolism has currently been observed in cancer and infection fields. Asparagine synthetase (AS) is responsible for the conversion of aspartate into Asn in an ATP-dependent manner, using ammonia or glutamine as a nitrogen source. There are two structurally distinct AS: the strictly ammonia dependent, type A, and the type B, which preferably uses glutamine. Absent in humans and present in trypanosomatids, AS-A was worthy of exploring as a potential drug target candidate. Appealingly, it was reported that AS-A was essential in Leishmania donovani, making it a promising drug target. In the work herein we demonstrate that Leishmania infantum AS-A, similarly to Trypanosoma spp. and L. donovani, is able to use both ammonia and glutamine as nitrogen donors. Moreover, we have successfully generated LiASA null mutants by targeted gene replacement in L. infantum, and these parasites do not display any significant growth or infectivity defect. Indeed, a severe impairment of in vitro growth was only observed when null mutants were cultured in asparagine limiting conditions. Altogether our results demonstrate that despite being important under asparagine limitation, LiAS-A is not essential for parasite survival, growth or infectivity in normal in vitro and in vivo conditions. Therefore we exclude AS-A as a suitable drug target against L. infantum parasites.
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Affiliation(s)
- Joana Faria
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Inês Loureiro
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Nuno Santarém
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Sandra Macedo-Ribeiro
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Protein Crystallography Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
| | - Joana Tavares
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Anabela Cordeiro-da-Silva
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
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Levefaudes M, Patin D, de Sousa-d'Auria C, Chami M, Blanot D, Hervé M, Arthur M, Houssin C, Mengin-Lecreulx D. Diaminopimelic Acid Amidation in Corynebacteriales: NEW INSIGHTS INTO THE ROLE OF LtsA IN PEPTIDOGLYCAN MODIFICATION. J Biol Chem 2015; 290:13079-94. [PMID: 25847251 DOI: 10.1074/jbc.m115.642843] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Indexed: 11/06/2022] Open
Abstract
A gene named ltsA was earlier identified in Rhodococcus and Corynebacterium species while screening for mutations leading to increased cell susceptibility to lysozyme. The encoded protein belonged to a huge family of glutamine amidotransferases whose members catalyze amide nitrogen transfer from glutamine to various specific acceptor substrates. We here describe detailed physiological and biochemical investigations demonstrating the specific role of LtsA protein from Corynebacterium glutamicum (LtsACg) in the modification by amidation of cell wall peptidoglycan diaminopimelic acid (DAP) residues. A morphologically altered but viable ΔltsA mutant was generated, which displays a high susceptibility to lysozyme and β-lactam antibiotics. Analysis of its peptidoglycan structure revealed a total loss of DAP amidation, a modification that was found in 80% of DAP residues in the wild-type polymer. The cell peptidoglycan content and cross-linking were otherwise not modified in the mutant. Heterologous expression of LtsACg in Escherichia coli yielded a massive and toxic incorporation of amidated DAP into the peptidoglycan that ultimately led to cell lysis. In vitro assays confirmed the amidotransferase activity of LtsACg and showed that this enzyme used the peptidoglycan lipid intermediates I and II but not, or only marginally, the UDP-MurNAc pentapeptide nucleotide precursor as acceptor substrates. As is generally the case for glutamine amidotransferases, either glutamine or NH4(+) could serve as the donor substrate for LtsACg. The enzyme did not amidate tripeptide- and tetrapeptide-truncated versions of lipid I, indicating a strict specificity for a pentapeptide chain length.
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Affiliation(s)
- Marjorie Levefaudes
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Delphine Patin
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Célia de Sousa-d'Auria
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Mohamed Chami
- the Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, CH-4058 Basel, Switzerland
| | - Didier Blanot
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Mireille Hervé
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Michel Arthur
- INSERM, UMR S1138, Centre de Recherche des Cordeliers, Equipe 12, F-75006 Paris, France, the Sorbonne Universités, UPMC Université Paris 06, UMR S1138, Centre de Recherche des Cordeliers, F-75006 Paris, France, and the Université Paris-Descartes, Sorbonne Paris Cité, UMR S1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Christine Houssin
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France,
| | - Dominique Mengin-Lecreulx
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, F-91198 Gif-sur-Yvette, France,
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Santana EA, Harrison A, Zhang X, Baker BD, Kelly BJ, White P, Liu Y, Munson RS. HrrF is the Fur-regulated small RNA in nontypeable Haemophilus influenzae. PLoS One 2014; 9:e105644. [PMID: 25157846 PMCID: PMC4144887 DOI: 10.1371/journal.pone.0105644] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 07/21/2014] [Indexed: 02/06/2023] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) are Gram-negative commensal bacteria that reside in the nasopharynx. NTHi can also cause multiple upper and lower respiratory tract diseases that include sinusitis, conjunctivitis, bronchitis, and otitis media. In numerous bacterial species the ferric uptake regulator (Fur) acts as a global regulator of iron homeostasis by negatively regulating the expression of iron uptake systems. However in NTHi strain 86-028NP and numerous other bacterial species there are multiple instances where Fur positively affects gene expression. It is known that many instances of positive regulation by Fur occur indirectly through a small RNA intermediate. However, no examples of small RNAs have been described in NTHi. Therefore we used RNA-Seq analysis to analyze the transcriptome of NTHi strain 86-028NPrpsL and an isogenic 86-028NPrpsLΔfur strain to identify Fur-regulated intergenic transcripts. From this analysis we identified HrrF, the first small RNA described in any Haemophilus species. Orthologues of this small RNA exist only among other Pasteurellaceae. Our analysis showed that HrrF is maximally expressed when iron levels are low. Additionally, Fur was shown to bind upstream of the hrrF promoter. RNA-Seq analysis was used to identify targets of HrrF which include genes whose products are involved in molybdate uptake, deoxyribonucleotide synthesis, and amino acid biosynthesis. The stability of HrrF is not dependent on the RNA chaperone Hfq. This study is the first step in an effort to investigate the role small RNAs play in altering gene expression in response to iron limitation in NTHi.
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Affiliation(s)
- Estevan A. Santana
- The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Alistair Harrison
- The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Xinjun Zhang
- School of Informatics and Computing, Indiana University, Bloomington, Indiana, United States of America
| | - Beth D. Baker
- The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Benjamin J. Kelly
- The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- The Biomedical Genomics Core, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Peter White
- The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- The Biomedical Genomics Core, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Yunlong Liu
- School of Informatics and Computing, Indiana University, Bloomington, Indiana, United States of America
| | - Robert S. Munson
- The Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
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Manhas R, Tripathi P, Khan S, Sethu Lakshmi B, Lal SK, Gowri VS, Sharma A, Madhubala R. Identification and functional characterization of a novel bacterial type asparagine synthetase A: a tRNA synthetase paralog from Leishmania donovani. J Biol Chem 2014; 289:12096-12108. [PMID: 24610810 DOI: 10.1074/jbc.m114.554642] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Asparagine is formed by two structurally distinct asparagine synthetases in prokaryotes. One is the ammonia-utilizing asparagine synthetase A (AsnA), and the other is asparagine synthetase B (AsnB) that uses glutamine or ammonia as a nitrogen source. In a previous investigation using sequence-based analysis, we had shown that Leishmania spp. possess asparagine-tRNA synthetase paralog asparagine synthetase A (LdASNA) that is ammonia-dependent. Here, we report the cloning, expression, and kinetic analysis of ASNA from Leishmania donovani. Interestingly, LdASNA was both ammonia- and glutamine-dependent. To study the physiological role of ASNA in Leishmania, gene deletion mutations were attempted via targeted gene replacement. Gene deletion of LdASNA showed a growth delay in mutants. However, chromosomal null mutants of LdASNA could not be obtained as the double transfectant mutants showed aneuploidy. These data suggest that LdASNA is essential for survival of the Leishmania parasite. LdASNA enzyme was recalcitrant toward crystallization so we instead crystallized and solved the atomic structure of its close homolog from Trypanosoma brucei (TbASNA) at 2.2 Å. A very significant conservation in active site residues is observed between TbASNA and Escherichia coli AsnA. It is evident that the absence of an LdASNA homolog from humans and its essentiality for the parasites make LdASNA a novel drug target.
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Affiliation(s)
- Reetika Manhas
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Pankaj Tripathi
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sameena Khan
- Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | | | - Shambhu Krishan Lal
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | | | - Amit Sharma
- Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Rentala Madhubala
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
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15
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Ito M, Kim YG, Tsuji H, Takahashi T, Kiwaki M, Nomoto K, Danbara H, Okada N. Transposon mutagenesis of probiotic Lactobacillus casei identifies asnH, an asparagine synthetase gene involved in its immune-activating capacity. PLoS One 2014; 9:e83876. [PMID: 24416179 PMCID: PMC3885529 DOI: 10.1371/journal.pone.0083876] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 11/08/2013] [Indexed: 11/18/2022] Open
Abstract
Lactobacillus casei ATCC 27139 enhances host innate immunity, and the J1 phage-resistant mutants of this strain lose the activity. A transposon insertion mutant library of L. casei ATCC 27139 was constructed, and nine J1 phage-resistant mutants out of them were obtained. Cloning and sequencing analyses identified three independent genes that were disrupted by insertion of the transposon element: asnH, encoding asparagine synthetase, and dnaJ and dnaK, encoding the molecular chaperones DnaJ and DnaK, respectively. Using an in vivo mouse model of Listeria infection, only asnH mutant showed deficiency in their ability to enhance host innate immunity, and complementation of the mutation by introduction of the wild-type asnH in the mutant strain recovered the immuno-augmenting activity. AsnH protein exhibited asparagine synthetase activity when the lysozyme-treated cell wall extracts of L. casei ATCC 27139 was added as substrate. The asnH mutants lost the thick and rigid peptidoglycan features that are characteristic to the wild-type cells, indicating that AsnH of L. casei is involved in peptidoglycan biosynthesis. These results indicate that asnH is required for the construction of the peptidoglycan composition involved in the immune-activating capacity of L. casei ATCC 27139.
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Affiliation(s)
- Masahiro Ito
- Department of Microbiology, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
| | - Yun-Gi Kim
- Department of Microbiology, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
| | - Hirokazu Tsuji
- Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo, Japan
| | - Takuya Takahashi
- Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo, Japan
| | - Mayumi Kiwaki
- Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo, Japan
| | - Koji Nomoto
- Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo, Japan
| | - Hirofumi Danbara
- Department of Microbiology, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
| | - Nobuhiko Okada
- Department of Microbiology, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
- * E-mail:
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16
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Loureiro I, Faria J, Clayton C, Ribeiro SM, Roy N, Santarém N, Tavares J, Cordeiro-da-Silva A. Knockdown of asparagine synthetase A renders Trypanosoma brucei auxotrophic to asparagine. PLoS Negl Trop Dis 2013; 7:e2578. [PMID: 24340117 PMCID: PMC3854871 DOI: 10.1371/journal.pntd.0002578] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 10/25/2013] [Indexed: 11/29/2022] Open
Abstract
Asparagine synthetase (AS) catalyzes the ATP-dependent conversion of aspartate into asparagine using ammonia or glutamine as nitrogen source. There are two distinct types of AS, asparagine synthetase A (AS-A), known as strictly ammonia-dependent, and asparagine synthetase B (AS-B), which can use either ammonia or glutamine. The absence of AS-A in humans, and its presence in trypanosomes, suggested AS-A as a potential drug target that deserved further investigation. We report the presence of functional AS-A in Trypanosoma cruzi (TcAS-A) and Trypanosoma brucei (TbAS-A): the purified enzymes convert L-aspartate into L-asparagine in the presence of ATP, ammonia and Mg2+. TcAS-A and TbAS-A use preferentially ammonia as a nitrogen donor, but surprisingly, can also use glutamine, a characteristic so far never described for any AS-A. TbAS-A knockdown by RNAi didn't affect in vitro growth of bloodstream forms of the parasite. However, growth was significantly impaired when TbAS-A knockdown parasites were cultured in medium with reduced levels of asparagine. As expected, mice infections with induced and non-induced T. brucei RNAi clones were similar to those from wild-type parasites. However, when induced T. brucei RNAi clones were injected in mice undergoing asparaginase treatment, which depletes blood asparagine, the mice exhibited lower parasitemia and a prolonged survival in comparison to similarly-treated mice infected with control parasites. Our results show that TbAS-A can be important under in vivo conditions when asparagine is limiting, but is unlikely to be suitable as a drug target. The amino acid asparagine is important not only for protein biosynthesis, but also for nitrogen homeostasis. Asparagine synthetase catalyzes the synthesis of this amino acid. There are two forms of asparagine synthetase, A and B. The presence of type A in trypanosomes, and its absence in humans, makes this protein a potential drug target. Trypanosomes are responsible for serious parasitic diseases that rely on limited drug therapeutic options for control. In our study we present a functional characterization of trypanosomes asparagine synthetase A. We describe that Trypanosoma brucei and Trypanosoma cruzi type A enzymes are able to use either ammonia or glutamine as a nitrogen donor, within the conversion of aspartate into asparagine. Furthermore, we show that asparagine synthetase A knockdown renders Trypanosoma brucei auxotrophic to asparagine. Overall, this study demonstrates that interfering with asparagine metabolism represents a way to control parasite growth and infectivity.
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Affiliation(s)
- Inês Loureiro
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
| | - Joana Faria
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
| | - Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Sandra Macedo Ribeiro
- Protein Crystallography Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
| | - Nilanjan Roy
- Ashok and Rita Patel Institute of Integrated Study and Research in Biotechnology and Allied Sciences, New Vallabh Vidyanagar, Gujarat, India
| | - Nuno Santarém
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
| | - Joana Tavares
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
- * E-mail: (JT); (ACdS)
| | - Anabela Cordeiro-da-Silva
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal
- Departamento de Ciências Biológicas, Faculdade de Farmácia da Universidade do Porto, Porto, Portugal
- * E-mail: (JT); (ACdS)
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17
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van Heeswijk WC, Westerhoff HV, Boogerd FC. Nitrogen assimilation in Escherichia coli: putting molecular data into a systems perspective. Microbiol Mol Biol Rev 2013; 77:628-95. [PMID: 24296575 PMCID: PMC3973380 DOI: 10.1128/mmbr.00025-13] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We present a comprehensive overview of the hierarchical network of intracellular processes revolving around central nitrogen metabolism in Escherichia coli. The hierarchy intertwines transport, metabolism, signaling leading to posttranslational modification, and transcription. The protein components of the network include an ammonium transporter (AmtB), a glutamine transporter (GlnHPQ), two ammonium assimilation pathways (glutamine synthetase [GS]-glutamate synthase [glutamine 2-oxoglutarate amidotransferase {GOGAT}] and glutamate dehydrogenase [GDH]), the two bifunctional enzymes adenylyl transferase/adenylyl-removing enzyme (ATase) and uridylyl transferase/uridylyl-removing enzyme (UTase), the two trimeric signal transduction proteins (GlnB and GlnK), the two-component regulatory system composed of the histidine protein kinase nitrogen regulator II (NRII) and the response nitrogen regulator I (NRI), three global transcriptional regulators called nitrogen assimilation control (Nac) protein, leucine-responsive regulatory protein (Lrp), and cyclic AMP (cAMP) receptor protein (Crp), the glutaminases, and the nitrogen-phosphotransferase system. First, the structural and molecular knowledge on these proteins is reviewed. Thereafter, the activities of the components as they engage together in transport, metabolism, signal transduction, and transcription and their regulation are discussed. Next, old and new molecular data and physiological data are put into a common perspective on integral cellular functioning, especially with the aim of resolving counterintuitive or paradoxical processes featured in nitrogen assimilation. Finally, we articulate what still remains to be discovered and what general lessons can be learned from the vast amounts of data that are available now.
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Qian G, Liu C, Wu G, Yin F, Zhao Y, Zhou Y, Zhang Y, Song Z, Fan J, Hu B, Liu F. AsnB, regulated by diffusible signal factor and global regulator Clp, is involved in aspartate metabolism, resistance to oxidative stress and virulence in Xanthomonas oryzae pv. oryzicola. MOLECULAR PLANT PATHOLOGY 2013; 14:145-57. [PMID: 23157387 PMCID: PMC6638903 DOI: 10.1111/j.1364-3703.2012.00838.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak in rice, which is a destructive disease worldwide. Xoc virulence factors are regulated by diffusible signal factor (DSF) and the global regulator Clp. In this study, we have demonstrated that asnB (XOC_3054), encoding an asparagine synthetase, is a novel virulence-related gene regulated by both DSF and Clp in Xoc. A sequence analysis revealed that AsnB is highly conserved in Xanthomonas. An asnB mutation in Xoc dramatically impaired pathogen virulence and growth rate in host rice, but did not affect the ability to trigger the hypersensitive response in nonhost (plant) tobacco. Compared with the wild-type strain, the asnB deletion mutant was unable to grow in basic MMX (-) medium (a minimal medium without ammonium sulphate as the nitrogen source) with or without 10 tested nitrogen sources, except asparagine. The disruption of asnB impaired pathogen resistance to oxidative stress and reduced the transcriptional expression of oxyR, katA and katG, which encode three important proteins responsible for hydrogen peroxide (H(2)O(2)) sensing and detoxification in Xanthomonas in the presence of H(2)O(2), and nine important known Xoc virulence-related genes in plant cell-mimicking medium. Furthermore, the asnB mutation did not affect extracellular protease activity, extracellular polysaccharide production, motility or chemotaxis. Taken together, our results demonstrate the role of asnB in Xanthomonas for the first time.
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Affiliation(s)
- Guoliang Qian
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
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19
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Gaufichon L, Masclaux-Daubresse C, Tcherkez G, Reisdorf-Cren M, Sakakibara Y, Hase T, Clément G, Avice JC, Grandjean O, Marmagne A, Boutet-Mercey S, Azzopardi M, Soulay F, Suzuki A. Arabidopsis thaliana ASN2 encoding asparagine synthetase is involved in the control of nitrogen assimilation and export during vegetative growth. PLANT, CELL & ENVIRONMENT 2013; 36:328-42. [PMID: 22789031 DOI: 10.1111/j.1365-3040.2012.02576.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We investigated the function of ASN2, one of the three genes encoding asparagine synthetase (EC 6.3.5.4), which is the most highly expressed in vegetative leaves of Arabidopsis thaliana. Expression of ASN2 and parallel higher asparagine content in darkness suggest that leaf metabolism involves ASN2 for asparagine synthesis. In asn2-1 knockout and asn2-2 knockdown lines, ASN2 disruption caused a defective growth phenotype and ammonium accumulation. The asn2 mutant leaves displayed a depleted asparagine and an accumulation of alanine, GABA, pyruvate and fumarate, indicating an alanine formation from pyruvate through the GABA shunt to consume excess ammonium in the absence of asparagine synthesis. By contrast, asparagine did not contribute to photorespiratory nitrogen recycle as photosynthetic net CO(2) assimilation was not significantly different between lines under both 21 and 2% O(2). ASN2 was found in phloem companion cells by in situ hybridization and immunolocalization. Moreover, lack of asparagine in asn2 phloem sap and lowered (15) N flux to sinks, accompanied by the delayed yellowing (senescence) of asn2 leaves, in the absence of asparagine support a specific role of asparagine in phloem loading and nitrogen reallocation. We conclude that ASN2 is essential for nitrogen assimilation, distribution and remobilization (via the phloem) within the plant.
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Affiliation(s)
- Laure Gaufichon
- INRA, UMR1318, Institut Jean-Pierre Bourgin, Département Adaptation des Plantes à l'Environnement, RD10, F-78000 Versailles, France
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20
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Genome-enabled determination of amino acid biosynthesis in Xanthomonas campestris pv. campestris and identification of biosynthetic pathways for alanine, glycine, and isoleucine by 13C-isotopologue profiling. Mol Genet Genomics 2011; 286:247-59. [DOI: 10.1007/s00438-011-0639-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/23/2011] [Indexed: 10/17/2022]
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21
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Dawlaty J, Zhang X, Fischbach MA, Clardy J. Dapdiamides, tripeptide antibiotics formed by unconventional amide ligases. JOURNAL OF NATURAL PRODUCTS 2010; 73:441-446. [PMID: 20041689 PMCID: PMC2846032 DOI: 10.1021/np900685z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Indexed: 05/28/2023]
Abstract
Construction of a genomic DNA library from Pantoea agglomerans strain CU0119 and screening against the plant pathogen Erwinia amylovora yielded a new family of antibiotics, dapdiamides A-E (1-5). The structures were established through 2D-NMR experiments and mass spectrometry, as well as the synthesis of dapdiamide A (1). Transposon mutagenesis of the active cosmid allowed identification of the biosynthetic gene cluster. The dapdiamide family's promiscuous biosynthetic pathway contains two unconventional amide ligases that are predicted to couple its constituent monomers.
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Affiliation(s)
| | | | | | - Jon Clardy
- To whom correspondence should be addressed. Tel: (617) 432-2845. Fax: (617) 432-6424. E-mail:
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PVAS3, a class-II ubiquitous asparagine synthetase from the common bean (Phaseolus vulgaris). Mol Biol Rep 2009; 36:2249-58. [PMID: 19130295 DOI: 10.1007/s11033-008-9441-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Accepted: 12/19/2008] [Indexed: 10/21/2022]
Abstract
A gene encoding a putative asparagine synthetase (AS; EC 6.3.5.4) has been isolated from common bean (Phaseolus vulgaris). A 2.4 kb cDNA clone of this gene (PVAS3) encodes a protein of 570 amino acids with a predicted molecular mass of 64,678 Da, an isoelectric point of 6.45, and a net charge of -5.9 at pH 7.0. The PVAS3 protein sequence conserves all the amino acid residues that are essential for glutamine-dependent AS, and PVAS3 complemented an E. coli asparagine auxotroph, that demonstrates that it encodes a glutamine-dependent AS. PVAS3 displayed significant similarity to other AS. It showed the highest similarity to soybean SAS3 (92.9% identity), rice AS (73.7% identity), Arabidopsis ASN2 (73.2%) and sunflower HAS2 (72.9%). A phylogenetic analysis revealed that PVAS3 belongs to class-II asparagine synthetases. Expression analysis by real-time RT-PCR revealed that PVAS3 is expressed ubiquitously and is not repressed by light.
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Zalkin H. The amidotransferases. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 66:203-309. [PMID: 8430515 DOI: 10.1002/9780470123126.ch5] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- H Zalkin
- Department of Biochemistry, Purdue University, West Lafayette, Indiana
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24
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Ren H, Liu J. AsnB is involved in natural resistance of Mycobacterium smegmatis to multiple drugs. Antimicrob Agents Chemother 2006; 50:250-5. [PMID: 16377694 PMCID: PMC1346815 DOI: 10.1128/aac.50.1.250-255.2006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacteria are naturally resistant to most common antibiotics and chemotherapeutic agents. The underlying molecular mechanisms are not fully understood. In this paper, we describe a hypersensitive mutant of Mycobacterium smegmatis, MS 2-39, which was isolated by screening for transposon insertion mutants of M. smegmatis mc2155 that exhibit increased sensitivity to rifampin, erythromycin, or novobiocin. The mutant MS 2-39 exhibited increased sensitivity to all three of the above mentioned antibiotics as well as fusidic acid, but its sensitivity to other antibiotics, including isoniazid, ethambutol, streptomycin, chloramphenicol, norfloxacin, tetracycline, and beta-lactams, remained unchanged. Uptake experiment with hydrophobic agents and cell wall lipid analysis suggest that the mutant cell wall is normal. The transposon insertion was localized within the asnB gene, which is predicted to encode a glutamine-dependent asparagine synthetase. Transformation of the mutant with wild-type asnB of mc2155 or asnB of Mycobacterium tuberculosis complemented the drug sensitivity phenotype. These results suggest that AsnB plays a role in the natural resistance of mycobacteria.
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Affiliation(s)
- Huiping Ren
- 4382 Medical Sciences Building, Department of Medical Genetics and Microbiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
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Mitani Y, Meng X, Kamagata Y, Tamura T. Characterization of LtsA from Rhodococcus erythropolis, an enzyme with glutamine amidotransferase activity. J Bacteriol 2005; 187:2582-91. [PMID: 15805504 PMCID: PMC1070375 DOI: 10.1128/jb.187.8.2582-2591.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nocardioform actinomycete Rhodococcus erythropolis has a characteristic cell wall structure. The cell wall is composed of arabinogalactan and mycolic acid and is highly resistant to the cell wall-lytic activity of lysozyme (muramidase). In order to improve the isolation of recombinant proteins from R. erythropolis host cells (N. Nakashima and T. Tamura, Biotechnol. Bioeng. 86:136-148, 2004), we isolated two mutants, L-65 and L-88, which are susceptible to lysozyme treatment. The lysozyme sensitivity of the mutants was complemented by expression of Corynebacterium glutamicum ltsA, which codes for an enzyme with glutamine amidotransferase activity that results from coupling of two reactions (a glutaminase activity and a synthetase activity). The lysozyme sensitivity of the mutants was also complemented by ltsA homologues from Bacillus subtilis and Mycobacterium tuberculosis, but the homologues from Streptomyces coelicolor and Escherichia coli did not complement the sensitivity. This result suggests that only certain LtsA homologues can confer lysozyme resistance. Wild-type recombinant LtsA from R. erythropolis showed glutaminase activity, but the LtsA enzymes from the L-88 and L-65 mutants displayed drastically reduced activity. Interestingly, an ltsA disruptant mutant, which expressed the mutated LtsA, changed from lysozyme sensitive to lysozyme resistant when NH(4)Cl was added into the culture media. The glutaminase activity of the LtsA mutants inactivated by site-directed mutagenesis was also restored by addition of NH(4)Cl, indicating that NH(3) can be used as an amide donor molecule. Taken together, these results suggest that LtsA is critically involved in mediating lysozyme resistance in R. erythropolis cells.
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Affiliation(s)
- Yasuo Mitani
- Proteolysis and Protein Turnover Research Group, Research Institute of Genome-Based Biofactory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan
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Reitzer L. Biosynthesis of Glutamate, Aspartate, Asparagine, L-Alanine, and D-Alanine. EcoSal Plus 2004; 1. [PMID: 26443364 DOI: 10.1128/ecosalplus.3.6.1.3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Indexed: 06/05/2023]
Abstract
Glutamate, aspartate, asparagine, L-alanine, and D-alanine are derived from intermediates of central metabolism, mostly the citric acid cycle, in one or two steps. While the pathways are short, the importance and complexity of the functions of these amino acids befit their proximity to central metabolism. Inorganic nitrogen (ammonia) is assimilated into glutamate, which is the major intracellular nitrogen donor. Glutamate is a precursor for arginine, glutamine, proline, and the polyamines. Glutamate degradation is also important for survival in acidic environments, and changes in glutamate concentration accompany changes in osmolarity. Aspartate is a precursor for asparagine, isoleucine, methionine, lysine, threonine, pyrimidines, NAD, and pantothenate; a nitrogen donor for arginine and purine synthesis; and an important metabolic effector controlling the interconversion of C3 and C4 intermediates and the activity of the DcuS-DcuR two-component system. Finally, L- and D-alanine are components of the peptide of peptidoglycan, and L-alanine is an effector of the leucine responsive regulatory protein and an inhibitor of glutamine synthetase (GS). This review summarizes the genes and enzymes of glutamate, aspartate, asparagine, L-alanine, and D-alanine synthesis and the regulators and environmental factors that control the expression of these genes. Glutamate dehydrogenase (GDH) deficient strains of E. coli, K. aerogenes, and S. enterica serovar Typhimurium grow normally in glucose containing (energy-rich) minimal medium but are at a competitive disadvantage in energy limited medium. Glutamate, aspartate, asparagine, L-alanine, and D-alanine have multiple transport systems.
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Tesson AR, Soper TS, Ciustea M, Richards NGJ. Revisiting the steady state kinetic mechanism of glutamine-dependent asparagine synthetase from Escherichia coli. Arch Biochem Biophys 2003; 413:23-31. [PMID: 12706338 DOI: 10.1016/s0003-9861(03)00118-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Escherichia coli asparagine synthetase B (AS-B) catalyzes the formation of asparagine from aspartate in an ATP-dependent reaction for which glutamine is the in vivo nitrogen source. In an effort to reconcile several different kinetic models that have been proposed for glutamine-dependent asparagine synthetases, we have used numerical methods to investigate the kinetic mechanism of AS-B. Our simulations demonstrate that literature proposals cannot reproduce the glutamine dependence of the glutamate/asparagine stoichiometry observed for AS-B, and we have therefore developed a new kinetic model that describes the behavior of AS-B more completely. The key difference between this new model and the literature proposals is the inclusion of an E.ATP.Asp.Gln quaternary complex that can either proceed to form asparagine or release ammonia through nonproductive glutamine hydrolysis. The implication of this model is that the two active sites in AS-B become coordinated only after formation of a beta-aspartyl-AMP intermediate in the synthetase site of the enzyme. The coupling of glutaminase and synthetase activities in AS is therefore different from that observed in all other well-characterized glutamine-dependent amidotransferases.
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Affiliation(s)
- Alan R Tesson
- Department of Chemistry, University of Florida, Gainesville 32611, USA
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Poggio S, Domeinzain C, Osorio A, Camarena L. The nitrogen assimilation control (Nac) protein represses asnC and asnA transcription in Escherichia coli. FEMS Microbiol Lett 2002; 206:151-6. [PMID: 11814655 DOI: 10.1111/j.1574-6968.2002.tb11001.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
In this work, we show that the expression of the asnA and asnC genes is regulated by the availability of ammonium in the growth medium. Our results suggest that, under nitrogen-limiting growth conditions, the nitrogen assimilation control (Nac) protein is involved in the repression of the asnC gene, whose product is required to activate the transcription of asnA. We also show that asparagine negatively affects the expression of asnA, independently of the presence of Nac. These results allow us to conclude that asnA transcription is regulated by two different mechanisms that respond to different effectors: nitrogen and asparagine availability.
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Affiliation(s)
- Sebastian Poggio
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ap. Postal 70-228, 04510, México, D.F., Mexico
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Trzebiatowski JR, Ragatz DM, de Bruijn FJ. Isolation and regulation of Sinorhizobium meliloti 1021 loci induced by oxygen limitation. Appl Environ Microbiol 2001; 67:3728-31. [PMID: 11472955 PMCID: PMC93079 DOI: 10.1128/aem.67.8.3728-3731.2001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Eleven Sinorhizobium meliloti 1021 loci whose expression was induced under low oxygen concentrations were identified in a collection of 5,000 strains carrying Tn5-1063 (luxAB) transcriptional reporter gene fusions. The 11 Tn5-1063-tagged loci were cloned and characterized. The dependence of the expression of the tagged loci on the FixL/FixJ oxygen-sensing two-component regulatory system was examined. Three of the loci were found to be dependent upon fixL and fixJ for their expression, while one locus showed a partial dependence. The remaining seven loci showed fixL- and fixJ-independent induction of expression in response to oxygen limitation. This suggests that in S. meliloti, additional regulatory system(s) exist that respond either directly or indirectly to oxygen limitation conditions.
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Affiliation(s)
- J R Trzebiatowski
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
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Bergès H, Checroun C, Guiral S, Garnerone AM, Boistard P, Batut J. A glutamine-amidotransferase-like protein modulates FixT anti-kinase activity in Sinorhizobium meliloti. BMC Microbiol 2001; 1:6. [PMID: 11389771 PMCID: PMC32199 DOI: 10.1186/1471-2180-1-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2001] [Accepted: 05/22/2001] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Nitrogen fixation gene expression in Sinorhizobium meliloti, the alfalfa symbiont, depends on a cascade of regulation that involves both positive and negative control. On top of the cascade, the two-component regulatory system FixLJ is activated under the microoxic conditions of the nodule. In addition, activity of the FixLJ system is inhibited by a specific anti-kinase protein, FixT. The physiological significance of this negative regulation by FixT was so far unknown. RESULTS We have isolated by random Tn5 mutagenesis a S. meliloti mutant strain that escapes repression by FixT. Complementation test and DNA analysis revealed that inactivation of an asparagine synthetase-like gene was responsible for the phenotype of the mutant. This gene, that was named asnO, encodes a protein homologous to glutamine-dependent asparagine synthetases. The asnO gene did not appear to affect asparagine biosynthesis and may instead serve a regulatory function in S. meliloti. We provide evidence that asnO is active during symbiosis. CONCLUSIONS Isolation of the asnO mutant argues for the existence of a physiological regulation associated with fixT and makes it unlikely that fixT serves a mere homeostatic function in S. meliloti. Our data suggest that asnO might control activity of the FixT protein, in a way that remains to be elucidated. A proposed role for asnO might be to couple nitrogen fixation gene expression in S. meliloti to the nitrogen needs of the cells.
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Affiliation(s)
- Hélène Bergès
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, UMR215 CNRS-INRA, BP27, 31326 Castanet-Tolosan Cedex, France
| | - Claire Checroun
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, UMR215 CNRS-INRA, BP27, 31326 Castanet-Tolosan Cedex, France
| | - Sébastien Guiral
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, UMR215 CNRS-INRA, BP27, 31326 Castanet-Tolosan Cedex, France
| | - Anne-Marie Garnerone
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, UMR215 CNRS-INRA, BP27, 31326 Castanet-Tolosan Cedex, France
| | - Pierre Boistard
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, UMR215 CNRS-INRA, BP27, 31326 Castanet-Tolosan Cedex, France
| | - Jacques Batut
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, UMR215 CNRS-INRA, BP27, 31326 Castanet-Tolosan Cedex, France
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Abstract
We present a summary of recent progress in understanding Escherichia coli K-12 gene and protein functions. New information has come both from classical biological experimentation and from using the analytical tools of functional genomics. The content of the E. coli genome can clearly be seen to contain elements acquired by horizontal transfer. Nevertheless, there is probably a large, stable core of >3500 genes that are shared among all E. coli strains. The gene-enzyme relationship is examined, and, in many cases, it exhibits complexity beyond a simple one-to-one relationship. Also, the E. coli genome can now be seen to contain many multiple enzymes that carry out the same or closely similar reactions. Some are similar in sequence and may share common ancestry; some are not. We discuss the concept of a minimal genome as being variable among organisms and obligatorily linked to their life styles and defined environmental conditions. We also address classification of functions of gene products and avenues of insight into the history of protein evolution.
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Affiliation(s)
- M Riley
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. ,
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Abstract
Three asparagine synthetase genes, asnB, asnH, and asnO (yisO), were predicted from the sequence of the Bacillus subtilis genome. We show here that the three genes are expressed differentially during cell growth. In a rich sporulation medium, expression of asnB was detected only during exponential growth, that of asnH was drastically elevated at the transition between exponential growth and stationary phase, and that of asnO was seen only later in sporulation. In a minimal medium, both asnB and asnH were expressed constitutively during exponential growth and in stationary phase, while the expression of asnO was not detected in either phase. However, when the minimal medium was supplemented with asparagine, only the expression of asnH was partially repressed. Transcription analyses revealed that asnB was possibly cotranscribed with a downstream gene, ytnA, while the asnH gene was transcribed as the fourth gene of an operon comprising yxbB, yxbA, yxnB, asnH, and yxaM. The asnO gene is a monocistronic operon, the expression of which was dependent on one of the sporulation sigma factors, sigma-E. Each of the three genes, carried on a low-copy-number plasmid, complemented the asparagine deficiency of an Escherichia coli strain lacking asparagine synthetases, indicating that all encode an asparagine synthetase. In B. subtilis, deletion of asnO or asnH, singly or in combination, had essentially no effect on growth rates in media with or without asparagine. In contrast, deletion of asnB led to a slow-growth phenotype, even in the presence of asparagine. A strain lacking all three genes still grew without asparagine, albeit very slowly, implying that B. subtilis might have yet another asparagine synthetase, not recognized by sequence analysis. The strains lacking asnO failed to sporulate, indicating an involvement of this gene in sporulation.
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Affiliation(s)
- K Yoshida
- Department of Biotechnology, Fukuyama University, Fukuyama, Hiroshima 729-0292, Japan.
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Osuna D, Gálvez G, Pineda M, Aguilar M. RT-PCR cloning, characterization and mRNA expression analysis of a cDNA encoding a type II asparagine synthetase in common bean. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1445:75-85. [PMID: 10209260 DOI: 10.1016/s0167-4781(99)00016-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Following a RT-PCR strategy based on the design of degenerate oligonucleotides resembling conserved domains of asparagine synthetase (AS; EC 6.3.5.4), we isolated a 2 kb cDNA clone (PVAS2) from root tissue of the common bean (Phaseolus vulgaris). PVAS2 encodes a protein of 584 amino acids with a predicted relative molecular mass of 65810 Da, an isoelectric point of 6.4, and a net charge of -7.2 at pH 7.0. The amino acid sequence of the protein encoded by PVAS2 is very similar to that encoded by the soybean SAS2 asparagine synthetase gene. The amino-terminal residues of the predicted PVAS2 protein are identical to the amino acids that constitute the glutamine-binding (GAT) domain of AS from other plant species, which suggests that the PVAS2 cDNA encodes a type II glutamine-dependent form of asparagine synthetase. Southern blot analysis indicates that the common bean AS is part of a small family composed of at least two genes. Expression analysis by Northern blot revealed that the PVAS2 transcript accumulates to a high level in roots and, to a lesser extent, in nodules and developing pods. Accumulation of the PVAS2 transcript in the root seems to be negatively regulated by light and sucrose, and positively regulated by nitrate.
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Affiliation(s)
- D Osuna
- Departamento de Bioquímica y Biología Molecular, e Instituto Andaluz de Biotecnología, Facultad de Ciencias, Universidad de Córdoba, Avda. San Alberto Magno, s/n. 14071, Córdoba, Spain
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34
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Curnow AW, Tumbula DL, Pelaschier JT, Min B, Söll D. Glutamyl-tRNA(Gln) amidotransferase in Deinococcus radiodurans may be confined to asparagine biosynthesis. Proc Natl Acad Sci U S A 1998; 95:12838-43. [PMID: 9789001 PMCID: PMC23620 DOI: 10.1073/pnas.95.22.12838] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/1998] [Indexed: 11/18/2022] Open
Abstract
Asparaginyl-tRNA (Asn-tRNA) and glutaminyl-tRNA (Gln-tRNA) are essential components of protein synthesis. They can be formed by direct acylation by asparaginyl-tRNA synthetase (AsnRS) or glutaminyl-tRNA synthetase (GlnRS). The alternative route involves transamidation of incorrectly charged tRNA. Examination of the preliminary genomic sequence of the radiation-resistant bacterium Deinococcus radiodurans suggests the presence of both direct and indirect routes of Asn-tRNA and Gln-tRNA formation. Biochemical experiments demonstrate the presence of AsnRS and GlnRS, as well as glutamyl-tRNA synthetase (GluRS), a discriminating and a nondiscriminating aspartyl-tRNA synthetase (AspRS). Moreover, both Gln-tRNA and Asn-tRNA transamidation activities are present. Surprisingly, they are catalyzed by a single enzyme encoded by three ORFs orthologous to Bacillus subtilis gatCAB. However, the transamidation route to Gln-tRNA formation is idled by the inability of the discriminating D. radiodurans GluRS to produce the required mischarged Glu-tRNAGln substrate. The presence of apparently redundant complete routes to Asn-tRNA formation, combined with the absence from the D. radiodurans genome of genes encoding tRNA-independent asparagine synthetase and the lack of this enzyme in D. radiodurans extracts, suggests that the gatCAB genes may be responsible for biosynthesis of asparagine in this asparagine prototroph.
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Affiliation(s)
- A W Curnow
- Department of Molecular Biophysics and Biochemistry, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520-8114, USA
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Abstract
This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715-1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.
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Affiliation(s)
- M K Berlyn
- Department of Biology and School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06520-8104, USA.
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Zalkin H, Smith JL. Enzymes utilizing glutamine as an amide donor. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 1998; 72:87-144. [PMID: 9559052 DOI: 10.1002/9780470123188.ch4] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Amide nitrogen from glutamine is a major source of nitrogen atoms incorporated biosynthetically into other amino acids, purine and pyrimidine bases, amino-sugars, and coenzymes. A family comprised of at least sixteen amidotransferases are known to catalyze amide nitrogen transfer from glutamine to their acceptor substrates. Recent fine structural advances, largely as a result of X-ray crystallography, now provide structure-based mechanisms that help to explain fundamental aspects of the catalytic and regulatory interactions of several of these aminotransferases. This chapter provides an overview of this recent progress made on the characterization of amidotransferase structure and mechanism.
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Boehlein SK, Walworth ES, Richards NG, Schuster SM. Mutagenesis and chemical rescue indicate residues involved in beta-aspartyl-AMP formation by Escherichia coli asparagine synthetase B. J Biol Chem 1997; 272:12384-92. [PMID: 9139684 DOI: 10.1074/jbc.272.19.12384] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Site-directed mutagenesis and kinetic studies have been employed to identify amino acid residues involved in aspartate binding and transition state stabilization during the formation of beta-aspartyl-AMP in the reaction mechanism of Escherichia coli asparagine synthetase B (AS-B). Three conserved amino acids in the segment defined by residues 317-330 appear particularly crucial for enzymatic activity. For example, when Arg-325 is replaced by alanine or lysine, the resulting mutant enzymes possess no detectable asparagine synthetase activity. The catalytic activity of the R325A AS-B mutant can, however, be restored to about 1/6 of that of wild-type AS-B by the addition of guanidinium HCl (GdmHCl). Detailed kinetic analysis of the rescued activity suggests that Arg-325 is involved in stabilization of a pentacovalent intermediate leading to the formation beta-aspartyl-AMP. This rescue experiment is the second example in which the function of a critical arginine residue that has been substituted by mutagenesis is restored by GdmHCl. Mutation of Thr-322 and Thr-323 also produces enzymes with altered kinetic properties, suggesting that these threonines are involved in aspartate binding and/or stabilization of intermediates en route to beta-aspartyl-AMP. These experiments are the first to identify residues outside of the N-terminal glutamine amide transfer domain that have any functional role in asparagine synthesis.
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Affiliation(s)
- S K Boehlein
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610, USA
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Hughes CA, Beard HS, Matthews BF. Molecular cloning and expression of two cDNAs encoding asparagine synthetase in soybean. PLANT MOLECULAR BIOLOGY 1997; 33:301-11. [PMID: 9037148 DOI: 10.1023/a:1005784202450] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Two cDNA clones (SAS1 and SAS2) encoding different isoforms of asparagine synthetase (AS; EC 6.3.5.4) were isolated. Their DNA sequences were determined and compared. The amino-terminal residues of the predicted SAS1 and SAS2 proteins were identical to those of the glutamine binding domain of AS from pea, asparagus, Arabidopsis and human, suggesting that SAS1 and SAS2 cDNAs encode the glutamine-dependent form of AS. The open reading frames of SAS1 and SAS2 encode a protein of 579 and 581 amino acids with predicted molecular weights of 65182 and 65608 Da respectively. Similarity of the deduced amino acid sequences of SAS1 and SAS2 with other known AS sequences were 92% and 93% for pea AS1; 91% and 96% for pea AS2; 88% and 91% for asparagus; 88% and 90.5% for Arabidopsis; 70.5% and 72.5% for E. coli asnB and 61% and 63% for man. A plasmid, pSAS2E, was constructed to express the soybean AS protein in Escherichia coli. Complementation experiments revealed that the soybean AS protein was functional in E. coli. Southern blot analysis indicated that the soybean AS is part of a small gene family. AS transcript was expressed in all tissues examined, but higher levels were seen in stem and root of light-grown tissue and leaves of dark-treated tissue.
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Affiliation(s)
- C A Hughes
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA
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39
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Isupov MN, Obmolova G, Butterworth S, Badet-Denisot MA, Badet B, Polikarpov I, Littlechild JA, Teplyakov A. Substrate binding is required for assembly of the active conformation of the catalytic site in Ntn amidotransferases: evidence from the 1.8 A crystal structure of the glutaminase domain of glucosamine 6-phosphate synthase. Structure 1996; 4:801-10. [PMID: 8805567 DOI: 10.1016/s0969-2126(96)00087-1] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Amidotransferases use the amide nitrogen of glutamine in a number of important biosynthetic reactions. They are composed of a glutaminase domain, which catalyzes the hydrolysis of glutamine to glutamate and ammonia, and a synthetase domain, catalyzing amination of the substrate. To gain insight into the mechanism of nitrogen transfer, we examined the structure of the glutaminase domain of glucosamine 6-phosphate synthase (GLMS). RESULTS The crystal structures of the enzyme complexed with glutamate and with a competitive inhibitor, Glu-hydroxamate, have been determined to 1.8 A resolution. The protein fold has structural homology to other members of the superfamily of N-terminal nucleophile (Ntn) hydrolases, being a sandwich of antiparallel beta sheets surrounded by two layers of alpha helices. CONCLUSIONS The structural homology between the glutaminase domain of GLMS and that of PRPP amidotransferase (the only other Ntn amidotransferase whose structure is known) indicates that they may have diverged from a common ancestor. Cys1 is the catalytic nucleophile in GLMS, and the nucleophilic character of its thiol group appears to be increased through general base activation by its own alpha-amino group. Cys1 can adopt two conformations, one active and one inactive; glutamine binding locks the residue in a predetermined conformation. We propose that when a nitrogen acceptor is present Cys1 is kept in the active conformation, explaining the phenomenon of substrate-induced activation of the enzyme, and that Arg26 is central in this coupling.
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Affiliation(s)
- M N Isupov
- Department of Chemistry and Biological Sciences, University of Exeter, UK
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40
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Parr IB, Boehlein SK, Dribben AB, Schuster SM, Richards NG. Mapping the aspartic acid binding site of Escherichia coli asparagine synthetase B using substrate analogs. J Med Chem 1996; 39:2367-78. [PMID: 8691431 DOI: 10.1021/jm9601009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Novel inhibitors of asparagine synthetase, that will lower circulating levels of blood asparagine, have considerable potential in developing new protocols for the treatment of acute lymphoblastic leukemia. We now report the indirect characterization of the aspartate binding site of Escherichia coli asparagine synthetase B (AS-B) using a number of stereochemically, and conformationally, defined aspartic acid analogs. Two compounds, prepared using novel reaction conditions for the stereospecific beta-functionalization of aspartic acid diesters, have been found to be competitive inhibitors with respect to aspartate in kinetic studies on AS-B. Chemical modification experiments employing [(fluorosulfonyl)benzoyl]adenosine (FSBA), an ATP analog, demonstrate that both inhibitors bind to the aspartate binding site of AS-B. Our results reveal that large steric alterations in the substrate are not tolerated by the enzyme, consistent with the failure of previous efforts to develop AS inhibitors using random screening approaches, and that all of the ionizable groups are placed in close proximity in the bound conformation of aspartate.
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Affiliation(s)
- I B Parr
- Department of Chemistry, University of Florida, Gainesville 32611, USA
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Badet-Denisot MA, Leriche C, Massière F, Badet B. Nitrogen transfer in E. coli glucosamine-6P synthase. Investigations using substrate and bisubstrate analogs. Bioorg Med Chem Lett 1995. [DOI: 10.1016/0960-894x(95)00119-e] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Boehlein S, Richards N, Schuster S. Glutamine-dependent nitrogen transfer in Escherichia coli asparagine synthetase B. Searching for the catalytic triad. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37307-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Brears T, Liu C, Knight TJ, Coruzzi GM. Ectopic Overexpression of Asparagine Synthetase in Transgenic Tobacco. PLANT PHYSIOLOGY 1993; 103:1285-1290. [PMID: 12232020 PMCID: PMC159117 DOI: 10.1104/pp.103.4.1285] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Here, we monitor the effects of ectopic overexpression of genes for pea asparagine synthetase (AS1) in transgenic tobacco (Nicotiana tabacum). The AS genes of pea and tobacco are normally expressed only during the dark phase of the diurnal growth cycle and specifically in phloem cells. A hybrid gene was constructed in which a pea AS1 cDNA was fused to the cauliflower mosaic virus 35S promoter. The 35S-AS1 gene was therefore ectopically expressed in all cell types in transgenic tobacco and constitutively expressed at high levels in both the light and the dark. Northern analysis demonstrated that the 35S-AS1 transgene was constitutively expressed at high levels in leaves of several independent transformants. Furthermore, amino acid analysis revealed a 10- to 100-fold increase in free asparagine in leaves of transgenic 35S-AS1 plants (construct z127) compared with controls. Plant growth analyses showed increases (although statistically insignificant) in growth phenotype during the vegetative stage of growth in 35S-AS1 transgenic lines. The 35S-AS1 construct was further modified by deletion of the glutamine-binding domain of the enzyme (gln[delta]AS1; construct z167). By analogy to animal AS, we reasoned that inhibition of glutamine-dependent AS activity might enhance the ammonia-dependent AS activity. The 3- to 19-fold increase in asparagine levels in the transgenic plants expressing gln[delta]AS1 compared with wild type suggests that the novel AS holoenzyme present in the transgenic plants (gln[delta]AS1 homodimer) has enhanced ammonia-dependent activity. These data indicate that manipulation of AS expression in transgenic plants causes an increase in nitrogen assimilation into asparagine, which in turn produces effects on plant growth and asparagine biosynthesis.
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Affiliation(s)
- T. Brears
- Department of Biology, New York University, 1009 Main Building, Washington Square East, New York, New York 10003 (T.B., C.L., G.M.C.)
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Abstract
A list of currently identified gene products of Escherichia coli is given, together with a bibliography that provides pointers to the literature on each gene product. A scheme to categorize cellular functions is used to classify the gene products of E. coli so far identified. A count shows that the numbers of genes concerned with small-molecule metabolism are on the same order as the numbers concerned with macromolecule biosynthesis and degradation. One large category is the category of tRNAs and their synthetases. Another is the category of transport elements. The categories of cell structure and cellular processes other than metabolism are smaller. Other subjects discussed are the occurrence in the E. coli genome of redundant pairs and groups of genes of identical or closely similar function, as well as variation in the degree of density of genetic information in different parts of the genome.
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Affiliation(s)
- M Riley
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543
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Hinchman SK, Henikoff S, Schuster SM. A relationship between asparagine synthetase A and aspartyl tRNA synthetase. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48471-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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46
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Scofield MA, Lewis WS, Schuster SM. Nucleotide sequence of Escherichia coli asnB and deduced amino acid sequence of asparagine synthetase B. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38244-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
In the last few years since the early NMR structural studies of small proteins such as glucagon (Braunet al.1983) andlacrepresser headpiece (Zuiderweget al.1984) the quality of the structure determinations have improved considerably. Of major importance has been the introduction of phase sensitive detection in the Tl dimension (Stateset al.1982; Marion & Wüthrich, 1983) which has allowed for absorption presentation of 2D data with the resulting enhancement in resolution, accuracy of coupling constant measurements and accuracy of peak volume integrations. Introduction of new pulse sequences, advances in instrumentation and further developments in the structure calculation algorithms have also helped improve the quality of NMR structural analyses of proteins.
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Affiliation(s)
- D M LeMaster
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208
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Kölling R, Gielow A, Seufert W, Kücherer C, Messer W. AsnC, a multifunctional regulator of genes located around the replication origin of Escherichia coli, oriC. MOLECULAR & GENERAL GENETICS : MGG 1988; 212:99-104. [PMID: 2836709 DOI: 10.1007/bf00322450] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The expression of the gidA gene which is located immediately counterclockwise of the replication origin of Escherichia coli, oriC, was found to be negatively regulated by the AsnC protein in an in vitro transcription-translation system. This effect is not due to simple repression of transcription originating at the gidA promoter, because the AsnC protein did not change the level of gidA promoter dependent transcription as analysed by promoter-galK fusions and by S1 mapping. From these data we conclude that the AsnC protein controls gidA gene expression at a post-transcriptional level. gidA is the third gene in the oriC region, besides asnA and asnC, whose expression is under AsnC control. However, the mechanisms involved are different: regulation of transcription in the case of asnA and asnC and post-transcriptional control of gidA. The gidA promoter was mapped by deletion analysis and by S1 mapping. We defined two regions that affect promoter activity negatively. Additional transcripts, regulated by AsnC, started more than 300 bp upstream of the gidA promoter and were found to enter the gidA region. These transcripts, originating either at the mioC and/or the ansC promoter traverse the replication origin.
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Affiliation(s)
- R Kölling
- Max-Planck-Institut für molekulare Genetik, Berlin
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