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Scholtysek L, Poetsch A, Hofmann E, Hemschemeier A. The activation of Chlamydomonas reinhardtii alpha amylase 2 by glutamine requires its N-terminal aspartate kinase-chorismate mutase-tyrA (ACT) domain. PLANT DIRECT 2024; 8:e609. [PMID: 38911017 PMCID: PMC11190351 DOI: 10.1002/pld3.609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/08/2024] [Accepted: 05/16/2024] [Indexed: 06/25/2024]
Abstract
The coordination of assimilation pathways for all the elements that make up cellular components is a vital task for every organism. Integrating the assimilation and use of carbon (C) and nitrogen (N) is of particular importance because of the high cellular abundance of these elements. Starch is one of the most important storage polymers of photosynthetic organisms, and a complex regulatory network ensures that biosynthesis and degradation of starch are coordinated with photosynthetic activity and growth. Here, we analyzed three starch metabolism enzymes of Chlamydomonas reinhardtii that we captured by a cyclic guanosine monophosphate (cGMP) affinity chromatography approach, namely, soluble starch synthase STA3, starch-branching enzyme SBE1, and α-amylase AMA2. While none of the recombinant enzymes was directly affected by the presence of cGMP or other nucleotides, suggesting an indirect binding to cGMP, AMA2 activity was stimulated in the presence of L-glutamine (Gln). This activating effect required the enzyme's N-terminal aspartate kinase-chorismate mutase-tyrA domain. Gln is the first N assimilation product and not only a central compound for the biosynthesis of N-containing molecules but also a recognized signaling molecule for the N status. Our observation suggests that AMA2 might be a means to coordinate N and C metabolism at the enzymatic level, increasing the liberation of C skeletons from starch when high Gln levels signal an abundance of assimilated N.
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Affiliation(s)
- Lisa Scholtysek
- Faculty of Biology and Biotechnology, PhotobiotechnologyRuhr University BochumBochumGermany
| | - Ansgar Poetsch
- Faculty of Biology and Biotechnology, Department for Plant BiochemistryRuhr University BochumBochumGermany
- School of Basic Medical SciencesNanchang UniversityNanchangChina
| | - Eckhard Hofmann
- Faculty of Biology and Biotechnology, Protein CrystallographyRuhr University BochumBochumGermany
| | - Anja Hemschemeier
- Faculty of Biology and Biotechnology, PhotobiotechnologyRuhr University BochumBochumGermany
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2
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Amala M, Nagarajan H, Ahila M, Nachiappan M, Veerapandiyan M, Vetrivel U, Jeyakanthan J. Unveiling the intricacies of allosteric regulation in aspartate kinase from the Wolbachia endosymbiont of Brugia Malayi: Mechanistic and therapeutic insights. Int J Biol Macromol 2024; 267:131326. [PMID: 38569988 DOI: 10.1016/j.ijbiomac.2024.131326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 03/04/2024] [Accepted: 03/31/2024] [Indexed: 04/05/2024]
Abstract
Aspartate kinase (AK), an enzyme from the Wolbachia endosymbiont of Brugia malayi (WBm), plays a pivotal role in the bacterial cell wall and amino acid biosynthesis, rendering it an attractive candidate for therapeutic intervention. Allosteric inhibition of aspartate kinase is a prevalent mode of regulation across microorganisms and plants, often modulated by end products such as lysine, threonine, methionine, or meso-diaminopimelate. The intricate and diverse nature of microbial allosteric regulation underscores the need for rigorous investigation. This study employs a combined experimental and computational approach to decipher the allosteric regulation of WBmAK. Molecular Dynamics (MD) simulations elucidate that ATP (cofactor) and ASP (substrate) binding induce a closed conformation, promoting enzymatic activity. In contrast, the binding of lysine (allosteric inhibitor) leads to enzyme inactivation and an open conformation. The enzymatic assay demonstrates the optimal activity of WBmAK at 28 °C and a pH of 8.0. Notably, the allosteric inhibition study highlights lysine as a more potent inhibitor compared to threonine. Importantly, this investigation sheds light on the allosteric mechanism governing WBmAK and imparts novel insights into structure-based drug discovery, paving the way for the development of effective inhibitors against filarial pathogens.
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Affiliation(s)
- Mathimaran Amala
- Structural Biology and Biocomputing Lab, Department of Bioinformatics, Alagappa University, Karaikudi 630004, Tamil Nadu, India
| | - Hemavathy Nagarajan
- Structural Biology and Biocomputing Lab, Department of Bioinformatics, Alagappa University, Karaikudi 630004, Tamil Nadu, India
| | - Mathimaran Ahila
- Structural Biology and Biocomputing Lab, Department of Bioinformatics, Alagappa University, Karaikudi 630004, Tamil Nadu, India
| | - Mutharasappan Nachiappan
- Structural and Computational Biology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Road, New Delhi 110 067, India
| | - Malaisamy Veerapandiyan
- Structural Biology and Biocomputing Lab, Department of Bioinformatics, Alagappa University, Karaikudi 630004, Tamil Nadu, India
| | - Umashankar Vetrivel
- Virology & Biotechnology/Bioinformatics Division, ICMR-National Institute for Research in Tuberculosis, Chennai, Tamil Nadu 600 031, India
| | - Jeyaraman Jeyakanthan
- Structural Biology and Biocomputing Lab, Department of Bioinformatics, Alagappa University, Karaikudi 630004, Tamil Nadu, India.
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3
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Fang H, Shan T, Gu H, Chen J, Qi Y, Li Y, Saeed M, Yuan J, Li P, Wang B. Identification and characterization of ACR gene family in maize for salt stress tolerance. FRONTIERS IN PLANT SCIENCE 2024; 15:1381056. [PMID: 38745920 PMCID: PMC11091409 DOI: 10.3389/fpls.2024.1381056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 04/15/2024] [Indexed: 05/16/2024]
Abstract
Background Members of the ACR gene family are commonly involved in various physiological processes, including amino acid metabolism and stress responses. In recent decades, significant progress has been made in the study of ACR genes in plants. However, little is known about their characteristics and function in maize. Methods In this study, ACR genes were identified from the maize genome, and their molecular characteristics, gene structure, gene evolution, gene collinearity analysis, cis-acting elements were analyzed. qRT-PCR technology was used to verify the expression patterns of the ZmACR gene family in different tissues under salt stress. In addition, Ectopic expression technique of ZmACR5 in Arabidopsis thaliana was utilized to identify its role in response to salt stress. Results A total of 28 ZmACR genes were identified, and their molecular characteristics were extensively described. Two gene pairs arising from segmented replication events were detected in maize, and 18 collinear gene pairs were detected between maize and 3 other species. Through phylogenetic analysis, three subgroups were revealed, demonstrating distinct divergence between monocotyledonous and dicotyledonous plants. Analysis of ZmACR cis-acting elements revealed the optional involvement of ZmACR genes in light response, hormone response and stress resistance. Expression analysis of 8 ZmACR genes under salt treatment clearly revealed their role in the response to salt stress. Ectopic overexpression of ZmACR5 in Arabidopsis notably reduced salt tolerance compared to that of the wild type under salt treatment, suggesting that ZmACR5 has a negative role in the response to salt stress. Conclusion Taken together, these findings confirmed the involvement of ZmACR genes in regulating salt stress and contributed significantly to our understanding of the molecular function of ACR genes in maize, facilitating further research in this field.
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Affiliation(s)
- Hui Fang
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Tingyu Shan
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Haijing Gu
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Junyu Chen
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Yingxiao Qi
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Yexiong Li
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Muhammad Saeed
- Department of Agricultural Sciences, Government College University, Faisalabad, Pakistan
| | | | - Ping Li
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Baohua Wang
- Ministry of Agricultural Scientific Observing and Experimental Station of Maize in Plain Area of Southern Region, School of Life Sciences, Nantong University, Nantong, Jiangsu, China
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4
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Carkaci-Salli N, Bewley MC, Tekin I, Flanagan JM, Vrana KE. The A328 V/E (rs2887147) polymorphisms in human tryptophan hydroxylase 2 compromise enzyme activity. Biochem Biophys Rep 2023; 35:101527. [PMID: 37608910 PMCID: PMC10440358 DOI: 10.1016/j.bbrep.2023.101527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/03/2023] [Accepted: 08/03/2023] [Indexed: 08/24/2023] Open
Abstract
Human tryptophan hydroxylase 2 (hTPH2) is the rate-limiting enzyme for serotonin biosynthesis in the brain. A number of naturally-occurring single nucleotide polymorphisms (SNPs) have been reported for hTPH2. We investigated the activity and kinetic characteristics of the most common missense polymorphism rs2887147 (A328 V/E; 0.92% allelic frequency for the two different reported SNPs at the same site) using bacterially expressed hTPH2. The recombinant full-length enzyme A328E had no measurable enzyme activity, but A328V displayed decreased enzyme activity (Vmax). A328V also displayed substrate inhibition and decreased stability compared to the wild-type enzyme. By contrast, in constructs lacking the N-terminal 150 amino acid regulatory domain, the A328V substitution had no effect; that is, there was no substrate inhibition, enzyme stabilities (for wild-type and A328V) were dramatically increased, and Vmax values were not different (while the A328E variant remained inactive). These findings, in combination with molecular modeling, suggest that substitutions at A328 affect catalytic activity by altering the conformational freedom of the regulatory domain. The reduced activity and substrate inhibition resulting from these polymorphisms may ultimately reduce serotonin synthesis and contribute to behavioral perturbations, emotional stress, and eating disorders.
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Affiliation(s)
- Nurgul Carkaci-Salli
- Departments of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Maria C. Bewley
- Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Izel Tekin
- Departments of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - John M. Flanagan
- Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Kent E. Vrana
- Departments of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
- Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
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5
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Liao HS, Chen YJ, Hsieh WY, Li YC, Hsieh MH. Arabidopsis ACT DOMAIN REPEAT9 represses glucose signaling pathways. PLANT PHYSIOLOGY 2023; 192:1532-1547. [PMID: 36843191 PMCID: PMC10231364 DOI: 10.1093/plphys/kiad127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/06/2023] [Accepted: 02/01/2023] [Indexed: 06/01/2023]
Abstract
Nutrient sensing and signaling are critical for plants to coordinate growth and development in response to nutrient availability. Plant ACT DOMAIN REPEAT (ACR) proteins have been proposed to serve as nutrient sensors, but their functions remain largely unknown. Here, we showed that Arabidopsis (Arabidopsis thaliana) ACR9 might function as a repressor in glucose (Glc) signaling pathways. ACR9 was highly expressed in the leaves, and its expression was downregulated by sugars. Interestingly, the acr9-1 and acr9-2 T-DNA insertion mutants were hypersensitive to Glc during seedling growth, development, and anthocyanin accumulation. Nitrogen deficiency increased the mutants' sensitivity to Glc. The expression of sugar-responsive genes was also significantly enhanced in the acr9 mutants. By contrast, the 35S:ACR9 and 35S:ACR9-GFP overexpression (OE) lines were insensitive to Glc during early seedling development. The Glc signaling pathway is known to interact with the plant hormone abscisic acid (ABA). Notably, the acr9 mutants were also hypersensitive to ABA during early seedling development. The Glc sensor HEXOKINASE1 (HXK1) and the energy sensor SUCROSE NON-FERMENTING1 (SNF1)-RELATED PROTEIN KINASE1 (SnRK1) are key components of the Glc signaling pathways. The acr9-1/hxk1-3 and acr9-1/snrk1 double mutants were no longer hypersensitive to Glc, indicating that functional HXK1 and SnRK1 were required for the acr9-1 mutant to be hypersensitive to Glc. Together, these results suggest that ACR9 is a repressor of the Glc signaling pathway, which may act independently or upstream of the HXK1-SnRK1 signaling module.
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Affiliation(s)
- Hong-Sheng Liao
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Ying-Jhu Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Wei-Yu Hsieh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Chiou Li
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Ming-Hsiun Hsieh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
- Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
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6
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Vedel IM, Prestel A, Zhang Z, Skawinska NT, Stark H, Harris P, Kragelund BB, Peters GHJ. Structural characterization of human tryptophan hydroxylase 2 reveals that L-Phe is superior to L-Trp as the regulatory domain ligand. Structure 2023:S0969-2126(23)00127-2. [PMID: 37119821 DOI: 10.1016/j.str.2023.04.004] [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: 12/17/2022] [Revised: 03/03/2023] [Accepted: 04/04/2023] [Indexed: 05/01/2023]
Abstract
Tryptophan hydroxylase 2 (TPH2) catalyzes the rate-limiting step in serotonin biosynthesis in the brain. Consequently, regulation of TPH2 is relevant for serotonin-related diseases, yet the regulatory mechanism of TPH2 is poorly understood and structural and dynamical insights are missing. We use NMR spectroscopy to determine the structure of a 47 N-terminally truncated variant of the regulatory domain (RD) dimer of human TPH2 in complex with L-Phe, and show that L-Phe is the superior RD ligand compared with the natural substrate, L-Trp. Using cryo-EM, we obtain a low-resolution structure of a similarly truncated variant of the complete tetrameric enzyme with dimerized RDs. The cryo-EM two-dimensional (2D) class averages additionally indicate that the RDs are dynamic in the tetramer and likely exist in a monomer-dimer equilibrium. Our results provide structural information on the RD as an isolated domain and in the TPH2 tetramer, which will facilitate future elucidation of TPH2's regulatory mechanism.
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Affiliation(s)
- Ida M Vedel
- Department of Chemistry, Technical University of Denmark, Kemitorvet, 2800 Kgs. Lyngby, Denmark
| | - Andreas Prestel
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark
| | - Zhenwei Zhang
- Department of Structural Dynamics, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Göttingen, Germany
| | - Natalia T Skawinska
- Department of Chemistry, Technical University of Denmark, Kemitorvet, 2800 Kgs. Lyngby, Denmark
| | - Holger Stark
- Department of Structural Dynamics, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Göttingen, Germany
| | - Pernille Harris
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Birthe B Kragelund
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark.
| | - Günther H J Peters
- Department of Chemistry, Technical University of Denmark, Kemitorvet, 2800 Kgs. Lyngby, Denmark.
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7
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Fitzpatrick PF. The aromatic amino acid hydroxylases: Structures, catalysis, and regulation of phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase. Arch Biochem Biophys 2023; 735:109518. [PMID: 36639008 DOI: 10.1016/j.abb.2023.109518] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/01/2023] [Accepted: 01/06/2023] [Indexed: 01/12/2023]
Abstract
The aromatic amino acid hydroxylases phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase are non-heme iron enzymes that catalyze key physiological reactions. This review discusses the present understanding of the common catalytic mechanism of these enzymes and recent advances in understanding the relationship between their structures and their regulation.
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Affiliation(s)
- Paul F Fitzpatrick
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229, USA.
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8
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Leong BJ, Hanson AD. Continuous Directed Evolution of a Feedback-Resistant Arabidopsis Arogenate Dehydratase in Plantized Escherichia coli. ACS Synth Biol 2023; 12:43-50. [PMID: 36534785 PMCID: PMC9872817 DOI: 10.1021/acssynbio.2c00511] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Indexed: 12/24/2022]
Abstract
Continuous directed evolution (CDE) is a powerful tool for enzyme engineering due to the depth and scale of evolutionary search that it enables. If suitably controlled and calibrated, CDE could be widely applied in plant breeding and biotechnology to improve plant enzymes ex planta. We tested this concept by evolving Arabidopsis arogenate dehydratase (AtADT2) for resistance to feedback inhibition. We used an Escherichia coli platform with a phenylalanine biosynthesis pathway reconfigured ("plantized") to mimic the plant pathway, a T7RNA polymerase-base deaminase hypermutation system (eMutaT7), and 4-fluorophenylalanine as selective agent. Selection schemes were prevalidated using a known feedback-resistant AtADT2 variant. We obtained variants that had 4-fluorophenylalanine resistance at least matching the known variant and that carried mutations in the ACT domain responsible for feedback inhibition. We conclude that ex planta CDE of plant enzymes in a microbial platform is a viable way to tailor characteristics that involve interaction with small molecules.
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Affiliation(s)
- Bryan J. Leong
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611, United States
| | - Andrew D. Hanson
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611, United States
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9
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Shao S, Li B, Sun Q, Guo P, Du Y, Huang J. Acetolactate synthases regulatory subunit and catalytic subunit genes VdILVs are involved in BCAA biosynthesis, microscletotial and conidial formation and virulence in Verticillium dahliae. Fungal Genet Biol 2022; 159:103667. [PMID: 35041986 DOI: 10.1016/j.fgb.2022.103667] [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: 10/08/2021] [Revised: 01/02/2022] [Accepted: 01/11/2022] [Indexed: 11/26/2022]
Abstract
Acetolactate synthase (AHAS) catalyses the first common step in the biosynthesis pathways of three branched-chain amino acids (BCAAs) of valine, isoleucine and leucine. Here, we characterized one regulatory subunit (VdILV6) and three catalytic subunits (VdILV2A, VdILV2B and VdILV2C) of AHAS from the important cotton Verticillium wilt fungus Verticillium dahliae. Phenotypic analysis showed that VdILV6 knockout mutants were auxotrophic for valine and isoleucine and were defective in conidial morphogenesis, hypha penetration and virulence to cotton, and lost ability of microscletotial formation. The growth of single catalytic subunit gene knockout mutants were significantly inhibited by leucine at higher concentration and single catalytic subunit gene knockout mutants showed significantly reduced virulence to cotton. VdILV2B knockout also led to obviously reduced microscletotial formation and conidial production, VdILV2C knockout led to reduced conidial production. Further studies suggested that both feedback inhibition by leucine and the inhibition by AHAS inhibiting herbicides of tribenuron and bispyribac resulted in significantly down-regulated expression of the four subunit VdILVs genes (VdILV2A, VdILV2B, VdILV2C and VdILV6). Any single catalytic subunit gene knockout led to reduced expression of the other three subunit genes, whereas VdILV6 knckout induced increased expression of the three catalytic subunit genes. VdILV2B, VdILV2C and VdILV6 knockout resulted in increased expression of VdCPC1 regulator gene of the cross-pathway control of amino acid biosynthesis. Taken together, these results indicate multiple roles of four VdILVs genes in the biosynthesis of BCAAs, virulence, fungal growth and development in the filamentous fungi V. dahliae.
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Affiliation(s)
- ShengNan Shao
- College of Agriculture / Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, Xinjiang Uygur Autonomous Region, Shihezi University, Shihezi 832003, Xinjiang
| | - Biao Li
- College of Agriculture / Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, Xinjiang Uygur Autonomous Region, Shihezi University, Shihezi 832003, Xinjiang
| | - Qi Sun
- College of Agriculture / Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, Xinjiang Uygur Autonomous Region, Shihezi University, Shihezi 832003, Xinjiang
| | - PeiRu Guo
- College of Agriculture / Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, Xinjiang Uygur Autonomous Region, Shihezi University, Shihezi 832003, Xinjiang
| | - YeJuan Du
- College of Agriculture / Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, Xinjiang Uygur Autonomous Region, Shihezi University, Shihezi 832003, Xinjiang.
| | - JiaFeng Huang
- College of Agriculture / Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, Xinjiang Uygur Autonomous Region, Shihezi University, Shihezi 832003, Xinjiang.
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10
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Yoo H, Shrivastava S, Lynch JH, Huang XQ, Widhalm JR, Guo L, Carter BC, Qian Y, Maeda HA, Ogas JP, Morgan JA, Marshall-Colón A, Dudareva N. Overexpression of arogenate dehydratase reveals an upstream point of metabolic control in phenylalanine biosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:737-751. [PMID: 34403557 DOI: 10.1111/tpj.15467] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
Out of the three aromatic amino acids, the highest flux in plants is directed towards phenylalanine, which is utilized to synthesize proteins and thousands of phenolic metabolites contributing to plant fitness. Phenylalanine is produced predominantly in plastids via the shikimate pathway and subsequent arogenate pathway, both of which are subject to complex transcriptional and post-transcriptional regulation. Previously, it was shown that allosteric feedback inhibition of arogenate dehydratase (ADT), which catalyzes the final step of the arogenate pathway, restricts flux through phenylalanine biosynthesis. Here, we show that in petunia (Petunia hybrida) flowers, which typically produce high phenylalanine levels, ADT regulation is relaxed, but not eliminated. Moderate expression of a feedback-insensitive ADT increased flux towards phenylalanine, while high overexpression paradoxically reduced phenylalanine formation. This reduction could be partially, but not fully, recovered by bypassing other known metabolic flux control points in the aromatic amino acid network. Using comparative transcriptomics, reverse genetics, and metabolic flux analysis, we discovered that transcriptional regulation of the d-ribulose-5-phosphate 3-epimerase gene in the pentose phosphate pathway controls flux into the shikimate pathway. Taken together, our findings reveal that regulation within and upstream of the shikimate pathway shares control over phenylalanine biosynthesis in the plant cell.
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Affiliation(s)
- Heejin Yoo
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, IN, 47907-2010, USA
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - Stuti Shrivastava
- Department of Plant Biology, University of Illinois Urbana-Champaign, 265 Morrill Hall, MC-116, Urbana, IL, 61801, USA
| | - Joseph H Lynch
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - Xing-Qi Huang
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - Joshua R Widhalm
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, IN, 47907-2010, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
| | - Longyun Guo
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - Benjamin C Carter
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
| | - Yichun Qian
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, IN, 47907-2010, USA
| | - Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Dr., Madison, WI, 53706, USA
| | - Joseph P Ogas
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
| | - John A Morgan
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
- Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Dr., West Lafayette, IN, 47907-2100, USA
| | - Amy Marshall-Colón
- Department of Plant Biology, University of Illinois Urbana-Champaign, 265 Morrill Hall, MC-116, Urbana, IL, 61801, USA
| | - Natalia Dudareva
- Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, IN, 47907-2010, USA
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN, 47907-2063, USA
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
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11
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Song J, Shang L, Chen S, Lu Y, Zhang Y, Ouyang B, Ye Z, Zhang J. Interactions between ShPP2-1, an F-box family gene, and ACR11A regulate cold tolerance of tomato. HORTICULTURE RESEARCH 2021; 8:148. [PMID: 34193825 PMCID: PMC8245493 DOI: 10.1038/s41438-021-00582-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 03/12/2021] [Accepted: 03/26/2021] [Indexed: 05/24/2023]
Abstract
There is a critical need to identify germplasm resources and genes that promote cold tolerance of tomato because global tomato production is threatened by cold stress. We found that the expression of an F-box gene family member named ShPP2-1 from Solanum habrochaites is cold inducible and studied its contribution to cold tolerance. Overexpression of ShPP2-1 in cultivated tomato (AC) reduced cold tolerance by intensifying damage to cell membranes. To explore the underlying molecular mechanism, we conducted a yeast two-hybrid library screen and found that a protein containing ACT domain repeats named ACR11A interacts with PP2-1. Overexpression of SlACR11A in AC enhanced the cold tolerance of seedlings and germinating seeds. Cold tolerance decreased in tomato plants that overexpressed both of these genes. Additionally, we performed seed germination experiments in the cold with 177 tomato accessions and identified two alleles of SlACR11A that differ in one single-nucleotide polymorphism. We found that one of these alleles, SlACR11AG, is significantly enriched in cold-tolerant tomato plants. Taken together, our findings indicate that the combination of low expression levels of PP2-1 and high expression levels of ACR11A can promote cold tolerance. These genes may therefore serve as direct targets for both genetic engineering and improvement projects that aim to enhance the cold tolerance of tomato.
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Affiliation(s)
- Jianwen Song
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China
| | - Lele Shang
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China
| | - Shiwei Chen
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China
| | - Yongen Lu
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuyang Zhang
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China
| | - Bo Ouyang
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhibiao Ye
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China.
| | - Junhong Zhang
- Key Laboratory of Horticultural Plant Biology (MOE) and National Center for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, 430070, China.
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12
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Molecular architecture of the acetohydroxyacid synthase holoenzyme. Biochem J 2020; 477:2439-2449. [DOI: 10.1042/bcj20200292] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 01/03/2023]
Abstract
The acetohydroxyacid synthase (AHAS) holoenzyme catalyzes the first step of branch-chain amino acid biosynthesis and is essential for plants and bacteria. It consists of a regulatory subunit (RSU) and a catalytic subunit (CSU). The allosteric mechanism of the AHAS holoenzyme has remained elusive for decades. Here, we determined the crystal structure of the AHAS holoenzyme, revealing the association between the RSU and CSU in an A2B2 mode. Structural analysis in combination with mutational studies demonstrated that the RSU dimer forms extensive interactions with the CSU dimer, in which a conserved salt bridge between R32 and D120 may act as a trigger to open the activation loop of the CSU, resulting in the activation of the CSU by the RSU. Our study reveals the activation mechanism of the AHAS holoenzyme.
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13
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The lineage and diversity of putative amino acid sensor ACR proteins in plants. Amino Acids 2020; 52:649-666. [PMID: 32306102 DOI: 10.1007/s00726-020-02844-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 04/11/2020] [Indexed: 10/24/2022]
Abstract
Amino acid metabolic enzymes often contain a regulatory ACT domain, named for aspartate kinase, chorismate mutase, and TyrA (prephenate dehydrogenase). Arabidopsis encodes 12 putative amino acid sensor ACT repeat (ACR) proteins, all containing ACT repeats but no identifiable catalytic domain. Arabidopsis ACRs comprise three groups based on domain composition and sequence: group I and II ACRs contain four ACTs each, and group III ACRs contain two ACTs. Previously, all three groups had been documented only in Arabidopsis. Here, we extended this to algae and land plants, showing that all three groups of ACRs are present in most, if not all, land plants, whereas among algal ACRs, although quite diverse, only group III is conserved. The appearance of canonical group I and II ACRs thus accompanied the evolution of plants from living in water to living on land. Alignment of ACTs from plant ACRs revealed a conserved motif, DRPGLL, at the putative ligand-binding site. Notably, the unique features of the DRPGLL motifs in each ACT domain are conserved in ACRs from algae to land plants. The conservation of plant ACRs is reminiscent of that of human cellular arginine sensor for mTORC1 (CASTOR1), a member of a small protein family highly conserved in animals. CASTOR proteins also have four ACT domains, although the sequence identities between ACRs and CASTORs are very low. Thus, plant ACRs and animal CASTORs may have adapted the regulatory ACT domains from a more ancient metabolic enzyme, and then evolved independently.
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14
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Arturo EC, Gupta K, Hansen MR, Borne E, Jaffe EK. Biophysical characterization of full-length human phenylalanine hydroxylase provides a deeper understanding of its quaternary structure equilibrium. J Biol Chem 2019; 294:10131-10145. [PMID: 31076506 PMCID: PMC6664189 DOI: 10.1074/jbc.ra119.008294] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/09/2019] [Indexed: 11/06/2022] Open
Abstract
Dysfunction of human phenylalanine hydroxylase (hPAH, EC 1.14.16.1) is the primary cause of phenylketonuria, the most common inborn error of amino acid metabolism. The dynamic domain rearrangements of this multimeric protein have thwarted structural study of the full-length form for decades, until now. In this study, a tractable C29S variant of hPAH (C29S) yielded a 3.06 Å resolution crystal structure of the tetrameric resting-state conformation. We used size-exclusion chromatography in line with small-angle X-ray scattering (SEC-SAXS) to analyze the full-length hPAH solution structure both in the presence and absence of Phe, which serves as both substrate and allosteric activators. Allosteric Phe binding favors accumulation of an activated PAH tetramer conformation, which is biophysically distinct in solution. Protein characterization with enzyme kinetics and intrinsic fluorescence revealed that the C29S variant and hPAH are otherwise equivalent in their response to Phe, further supported by their behavior on various chromatography resins and by analytical ultracentrifugation. Modeling of resting-state and activated forms of C29S against SAXS data with available structural data created and evaluated several new models for the transition between the architecturally distinct conformations of PAH and highlighted unique intra- and inter-subunit interactions. Three best-fitting alternative models all placed the allosteric Phe-binding module 8-10 Å farther from the tetramer center than do all previous models. The structural insights into allosteric activation of hPAH reported here may help inform ongoing efforts to treat phenylketonuria with novel therapeutic approaches.
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Affiliation(s)
- Emilia C Arturo
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
- the Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, and
| | - Kushol Gupta
- the Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Michael R Hansen
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
| | - Elias Borne
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
| | - Eileen K Jaffe
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111,
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15
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Wang W, Dai Y, Wang M, Yang W, Zhao D. Transcriptome Dynamics of Double Recessive Mutant, o2o2o16o16, Reveals the Transcriptional Mechanisms in the Increase of Its Lysine and Tryptophan Content in Maize. Genes (Basel) 2019; 10:genes10040316. [PMID: 31018625 PMCID: PMC6523931 DOI: 10.3390/genes10040316] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 11/16/2022] Open
Abstract
In maize, pyramiding of o2 and o16 alleles can greatly improve the nutritional quality of grains. To dissect its molecular mechanism, we created a double recessive mutant line, o2o2o16o16, by introgression of the o2 and o16 alleles into the wild-type maize inbred line, by molecular marker-assisted backcross selection. The kernels (18 day after pollination (DAP), 28 DAP, and 38 DAP) of the o2o2o16o16 mutant and its parent lines were subject to RNA sequencing (RNA-Seq). The RNA-Seq analysis revealed that 59 differentially expressed genes (DEGs) were involved in lysine metabolism and 43 DEGs were involved in tryptophan metabolism. Among them, the genes encoding AK, ASADH, and Dap-F in the lysine synthesis pathway were upregulated at different stages of endosperm development, promoting the synthesis of lysine. Meanwhile, the genes encoding LKR/SDH and L-PO in the lysine degradation pathway were downregulated, inhibiting the degradation of lysine. Moreover, the genes encoding TAA and YUC in the tryptophan metabolic pathway were downregulated, restraining the degradation of tryptophan. Thus, pyramiding o2 and o16 alleles could increase the lysine and tryptophan content in maize. These above results would help to uncover the molecular mechanisms involved in the increase in lysine and the tryptophan content, through the introgression of o2 and o16 alleles into the wild-type maize.
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Affiliation(s)
- Wei Wang
- The State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, The Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guizhou University, Guiyang 550025, China.
- Guizhou Institute of Upland Food Crops, Guiyang Station for DUS Testing Center of New Plant Varieties (MOA), Guizhou Academy of Agricultural Sciences, Guiyang 550006, China.
| | - Yi Dai
- The State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, The Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guizhou University, Guiyang 550025, China.
| | - Mingchun Wang
- Guizhou Institute of Upland Food Crops, Guiyang Station for DUS Testing Center of New Plant Varieties (MOA), Guizhou Academy of Agricultural Sciences, Guiyang 550006, China.
| | - Wenpeng Yang
- Guizhou Institute of Upland Food Crops, Guiyang Station for DUS Testing Center of New Plant Varieties (MOA), Guizhou Academy of Agricultural Sciences, Guiyang 550006, China.
| | - Degang Zhao
- The State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, The Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guizhou University, Guiyang 550025, China.
- Guizhou Institute of Upland Food Crops, Guiyang Station for DUS Testing Center of New Plant Varieties (MOA), Guizhou Academy of Agricultural Sciences, Guiyang 550006, China.
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16
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Xie Y, Wen X, Zhao D, Niu C, Zhao Y, Qi H, Xi Z. Interactions between the ACT Domains and Catalytic Subunits of Acetohydroxyacid Synthases (AHASs) from Different Species. Chembiochem 2018; 19:2387-2394. [DOI: 10.1002/cbic.201800367] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/16/2018] [Indexed: 01/05/2023]
Affiliation(s)
- Yonghui Xie
- State Key Laboratory of Elemento-Organic Chemistry; Department of Chemical Biology; National Pesticide Engineering Research Center (Tianjin); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); College of Chemistry; Nankai University; Tianjin 300071 P.R. China
| | - Xin Wen
- State Key Laboratory of Elemento-Organic Chemistry; Department of Chemical Biology; National Pesticide Engineering Research Center (Tianjin); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); College of Chemistry; Nankai University; Tianjin 300071 P.R. China
| | - Dongmei Zhao
- State Key Laboratory of Elemento-Organic Chemistry; Department of Chemical Biology; National Pesticide Engineering Research Center (Tianjin); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); College of Chemistry; Nankai University; Tianjin 300071 P.R. China
| | - Congwei Niu
- State Key Laboratory of Elemento-Organic Chemistry; Department of Chemical Biology; National Pesticide Engineering Research Center (Tianjin); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); College of Chemistry; Nankai University; Tianjin 300071 P.R. China
| | - Yuefang Zhao
- State Key Laboratory of Elemento-Organic Chemistry; Department of Chemical Biology; National Pesticide Engineering Research Center (Tianjin); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); College of Chemistry; Nankai University; Tianjin 300071 P.R. China
| | - Haoman Qi
- State Key Laboratory of Elemento-Organic Chemistry; Department of Chemical Biology; National Pesticide Engineering Research Center (Tianjin); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); College of Chemistry; Nankai University; Tianjin 300071 P.R. China
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry; Department of Chemical Biology; National Pesticide Engineering Research Center (Tianjin); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); College of Chemistry; Nankai University; Tianjin 300071 P.R. China
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17
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ACR11 modulates levels of reactive oxygen species and salicylic acid-associated defense response in Arabidopsis. Sci Rep 2018; 8:11851. [PMID: 30087396 PMCID: PMC6081435 DOI: 10.1038/s41598-018-30304-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/27/2018] [Indexed: 01/10/2023] Open
Abstract
The ACT domain (aspartate kinase, chorismate mutase and TyrA), an allosteric effector binding domain, is commonly found in amino acid metabolic enzymes. In addition to ACT domain-containing enzymes, plants have a novel family of ACT domain repeat (ACR) proteins, which do not contain any recognizable catalytic domain. Arabidopsis has 12 ACR proteins, whose functions are largely unknown. To study the functions of Arabidopsis ACR11, we have characterized two independent T-DNA insertion mutants, acr11-2 and acr11-3. RNA gel-blot analysis revealed that the expression of wild-type ACR11 transcripts was not detectable in the acr11 mutants. Interestingly, a lesion-mimic phenotype occurs in some rosette leaves of the acr11 mutants. In addition, high levels of reactive oxygen species (ROS), salicylic acid (SA), and callose accumulate in the mutant leaves when grown under normal conditions. The expression of several SA marker genes and the key SA biosynthetic gene ISOCHORISMATE SYNTHASE1 is up-regulated in the acr11 mutants. Furthermore, the acr11 mutants are more resistant to the infection of bacterial pathogen Pseudomonas syringae pathovar tomato DC3000. These results suggest that ACR11 may be directly or indirectly involved in the regulation of ROS and SA accumulation, which in turn modulates SA-associated defense responses and disease resistance in Arabidopsis.
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18
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Mechanistic insights into the allosteric regulation of Pseudomonas aeruginosa aspartate kinase. Biochem J 2018; 475:1107-1119. [PMID: 29382741 DOI: 10.1042/bcj20170829] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 01/18/2018] [Accepted: 01/24/2018] [Indexed: 02/05/2023]
Abstract
In plants and microorganisms, aspartate kinase (AK) catalyzes an initial commitment step of the aspartate family amino acid biosynthesis. Owing to various structural organizations, AKs from different species show tremendous diversity and complex allosteric controls. We report the crystal structure of AK from Pseudomonas aeruginosa (PaAK), a typical α2β2 hetero-tetrameric enzyme, in complex with inhibitory effectors. Distinctive features of PaAK are revealed by structural and biochemical analyses. Essentially, the open conformation of Lys-/Thr-bound PaAK structure clarifies the inhibitory mechanism of α2β2-type AK. Moreover, the various inhibitory effectors of PaAK have been identified and a general amino acid effector motif of AK family is described.
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19
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Burschowsky D, Thorbjørnsrud HV, Heim JB, Fahrig-Kamarauskaitė JR, Würth-Roderer K, Kast P, Krengel U. Inter-Enzyme Allosteric Regulation of Chorismate Mutase in Corynebacterium glutamicum: Structural Basis of Feedback Activation by Trp. Biochemistry 2017; 57:557-573. [PMID: 29178787 DOI: 10.1021/acs.biochem.7b01018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Corynebacterium glutamicum is widely used for the industrial production of amino acids, nucleotides, and vitamins. The shikimate pathway enzymes DAHP synthase (CgDS, Cg2391) and chorismate mutase (CgCM, Cgl0853) play a key role in the biosynthesis of aromatic compounds. Here we show that CgCM requires the formation of a complex with CgDS to achieve full activity, and that both CgCM and CgDS are feedback regulated by aromatic amino acids binding to CgDS. Kinetic analysis showed that Phe and Tyr inhibit CgCM activity by inter-enzyme allostery, whereas binding of Trp to CgDS strongly activates CgCM. Mechanistic insights were gained from crystal structures of the CgCM homodimer, tetrameric CgDS, and the heterooctameric CgCM-CgDS complex, refined to 1.1, 2.5, and 2.2 Å resolution, respectively. Structural details from the allosteric binding sites reveal that DAHP synthase is recruited as the dominant regulatory platform to control the shikimate pathway, similar to the corresponding enzyme complex from Mycobacterium tuberculosis.
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Affiliation(s)
| | | | - Joel B Heim
- Department of Chemistry, University of Oslo , NO-0315 Oslo, Norway
| | | | | | - Peter Kast
- Laboratory of Organic Chemistry, ETH Zurich , CH-8093 Zurich, Switzerland
| | - Ute Krengel
- Department of Chemistry, University of Oslo , NO-0315 Oslo, Norway
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20
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Tidemand KD, Peters GH, Harris P, Stensgaard E, Christensen HEM. Isoform-Specific Substrate Inhibition Mechanism of Human Tryptophan Hydroxylase. Biochemistry 2017; 56:6155-6164. [PMID: 29035515 DOI: 10.1021/acs.biochem.7b00763] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tryptophan hydroxylase (TPH) catalyzes the initial and rate-limiting step in the biosynthesis of serotonin, which is associated with a variety of disorders such as depression and irritable bowel syndrome. TPH exists in two isoforms: TPH1 and TPH2. TPH1 catalyzes the initial step in the synthesis of serotonin in the peripheral tissues, while TPH2 catalyzes this step in the brain. In this study, the steady-state kinetic mechanism for the catalytic domain of human TPH1 has been determined. Varying substrate tryptophan (Trp) and tetrahydrobiopterin (BH4) results in a hybrid Ping Pong-ordered mechanism in which the reaction can either occur through a Ping Pong or a sequential mechanism depending on the concentration of tryptophan. The catalytic domain of TPH1 shares a sequence identity of 81% with TPH2. Despite the high sequence identity, differences in the kinetic parameters of the isoforms have been identified; i.e., only TPH1 displays substrate tryptophan inhibition. This study demonstrates that the difference can be traced to an active site loop which displays different properties in the TPH isoforms. Steady-state kinetic results of the isoforms, and variants with point mutations in a loop lining the active site, show that the kinetic parameters of only TPH1 are significantly changed upon mutations. Mutations in the active site loop of TPH1 result in an increase in the substrate inhibition constant, Ki, and therefore turnover rate. Molecular dynamics simulations reveal that this substrate inhibition mechanism occurs through a closure of the cosubstrate, BH4, binding pocket, which is induced by Trp binding.
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Affiliation(s)
- Kasper D Tidemand
- Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
| | - Günther H Peters
- Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
| | - Pernille Harris
- Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
| | - Eva Stensgaard
- Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
| | - Hans E M Christensen
- Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
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21
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Tidemand KD, Christensen HEM, Hoeck N, Harris P, Boesen J, Peters GH. Stabilization of tryptophan hydroxylase 2 by l-phenylalanine-induced dimerization. FEBS Open Bio 2016; 6:987-999. [PMID: 27761358 PMCID: PMC5055035 DOI: 10.1002/2211-5463.12100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/20/2016] [Accepted: 06/29/2016] [Indexed: 12/12/2022] Open
Abstract
Tryptophan hydroxylase 2 (TPH2) catalyses the initial and rate‐limiting step in the biosynthesis of serotonin, which is associated with a variety of disorders such as depression, obsessive compulsive disorder, and schizophrenia. Full‐length TPH2 is poorly characterized due to low purification quantities caused by its inherent instability. Three truncated variants of human TPH2 (rchTPH2; regulatory and catalytic domain, NΔ47‐rchTPH2; truncation of 47 residues in the N terminus of rchTPH2, and chTPH2; catalytic domain) were expressed, purified, and examined for changes in transition temperature, inactivation rate, and oligomeric state. chTPH2 displayed 14‐ and 11‐fold higher half‐lives compared to rchTPH2 and NΔ47‐rchTPH2, respectively. Differential scanning calorimetry experiments demonstrated that this is caused by premature unfolding of the less stable regulatory domain. By differential scanning fluorimetry, the unfolding transitions of rchTPH2 and NΔ47‐rchTPH2 are found to shift from polyphasic to apparent two‐state by the addition of l‐Trp or l‐Phe. Analytical gel filtration revealed that rchTPH2 and NΔ47‐rchTPH2 reside in a monomer–dimer equilibrium which is significantly shifted toward dimer in the presence of l‐Phe. The dimerizing effect induced by l‐Phe is accompanied by a stabilizing effect, which resulted in a threefold increase in half‐lives of rchTPH2 and NΔ47‐rchTPH2. Addition of l‐Phe to the purification buffer significantly increases the purification yields, which will facilitate characterization of hTPH2.
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Affiliation(s)
- Kasper D Tidemand
- Department of Chemistry Technical University of Denmark Kongens Lyngby Denmark
| | | | - Niclas Hoeck
- Department of Chemistry Technical University of Denmark Kongens Lyngby Denmark
| | - Pernille Harris
- Department of Chemistry Technical University of Denmark Kongens Lyngby Denmark
| | - Jane Boesen
- Department of Chemistry Technical University of Denmark Kongens Lyngby Denmark
| | - Günther H Peters
- Department of Chemistry Technical University of Denmark Kongens Lyngby Denmark
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22
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Watson E, Yilmaz LS, Walhout AJM. Understanding Metabolic Regulation at a Systems Level: Metabolite Sensing, Mathematical Predictions, and Model Organisms. Annu Rev Genet 2016; 49:553-75. [PMID: 26631516 DOI: 10.1146/annurev-genet-112414-055257] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabolic networks are extensively regulated to facilitate tissue-specific metabolic programs and robustly maintain homeostasis in response to dietary changes. Homeostatic metabolic regulation is achieved through metabolite sensing coupled to feedback regulation of metabolic enzyme activity or expression. With a wealth of transcriptomic, proteomic, and metabolomic data available for different cell types across various conditions, we are challenged with understanding global metabolic network regulation and the resulting metabolic outputs. Stoichiometric metabolic network modeling integrated with "omics" data has addressed this challenge by generating nonintuitive, testable hypotheses about metabolic flux rewiring. Model organism studies have also yielded novel insight into metabolic networks. This review covers three topics: the feedback loops inherent in metabolic regulatory networks, metabolic network modeling, and interspecies studies utilizing Caenorhabditis elegans and various bacterial diets that have revealed novel metabolic paradigms.
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Affiliation(s)
- Emma Watson
- Program in Systems Biology, Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605; , ,
| | - L Safak Yilmaz
- Program in Systems Biology, Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605; , ,
| | - Albertha J M Walhout
- Program in Systems Biology, Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605; , ,
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23
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Rosenberg J, Müller P, Lentes S, Thiele MJ, Zeigler DR, Tödter D, Paulus H, Brantl S, Stülke J, Commichau FM. ThrR, a DNA‐binding transcription factor involved in controlling threonine biosynthesis in
Bacillus subtilis. Mol Microbiol 2016; 101:879-93. [DOI: 10.1111/mmi.13429] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Jonathan Rosenberg
- Department of General MicrobiologyGeorg August University GöttingenGrisebachstr. 8Göttingen37077 Germany
| | - Peter Müller
- Department of GeneticsBacterial Genetics, Friedrich Schiller University JenaJena Germany
| | - Sabine Lentes
- Department of General MicrobiologyGeorg August University GöttingenGrisebachstr. 8Göttingen37077 Germany
| | - Martin J. Thiele
- Department of General MicrobiologyGeorg August University GöttingenGrisebachstr. 8Göttingen37077 Germany
| | | | - Dominik Tödter
- Department of General MicrobiologyGeorg August University GöttingenGrisebachstr. 8Göttingen37077 Germany
| | - Henry Paulus
- Boston Biomedical Research InstituteBoston MA USA
| | - Sabine Brantl
- Department of GeneticsBacterial Genetics, Friedrich Schiller University JenaJena Germany
| | - Jörg Stülke
- Department of General MicrobiologyGeorg August University GöttingenGrisebachstr. 8Göttingen37077 Germany
| | - Fabian M. Commichau
- Department of General MicrobiologyGeorg August University GöttingenGrisebachstr. 8Göttingen37077 Germany
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24
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Valera MJ, Mas A, Streit WR, Mateo E. GqqA, a novel protein in Komagataeibacter europaeus involved in bacterial quorum quenching and cellulose formation. Microb Cell Fact 2016; 15:88. [PMID: 27221658 PMCID: PMC4879726 DOI: 10.1186/s12934-016-0482-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 05/03/2016] [Indexed: 01/10/2023] Open
Abstract
Background We report on the functional screening and identification of an active quorum quenching (QQ) gene in the Komagataeibacter europaeus strain CECT 8546, which is a member of the acetic acid bacteria (AAB). Results Using a previously published screening protocol (Schipper et al., in Appl Environ Microbiol 75:224–233, 2009. doi: 10.1128/AEM.01389-08) for QQ genes, we identified a single gene, designated gqqA, that interfered strongly with bacterial quorum sensing (QS) in various reporter strains. It encodes for a 281-amino acid protein with a molecular mass of 30 kDa. Although the GqqA protein is similar to predicted prephenate dehydratases, it does not complement Escherichia coli mutants of the pheA gene, thus indicating a potentially different function. Recombinant GqqA protein attenuated QS-dependent pyocyanin production and swarming motility in the Pseudomonas aeruginosa strain PAO1. Moreover, GqqA quenched the QS response of the Agrobacterium tumefaciens NTL4 and the Chromobacterium violaceum CV026 reporter strains. Interestingly, the addition of recombinant GqqA protein to growing cultures of the Komagataeibacter europaeus strain CECT 8546 altered the cellulose production phenotype of CECT 8546 and other AAB strains. In the presence of GqqA protein, cells were planktonic, and no visible cellulose biofilms formed. The addition of low levels of N-acylhomoserine lactones maintained the biofilm formation phenotype. Conclusions Our data provide evidence for an interconnection between QS and AAB cellulose biofilm formation as well as QQ activity of the GqqA protein. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0482-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Maria José Valera
- Biotecnología Enológica. Dept. Bioquímica i Biotecnologia, Facultat d'Enologia, Universitat Rovira i Virgili, C/Marcel.lí Domingo s/n., 43007, Tarragona, Spain
| | - Albert Mas
- Biotecnología Enológica. Dept. Bioquímica i Biotecnologia, Facultat d'Enologia, Universitat Rovira i Virgili, C/Marcel.lí Domingo s/n., 43007, Tarragona, Spain
| | - Wolfgang R Streit
- Abteilung für Mikrobiologie und Biotechnologie, Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststr. 18, 22609, Hamburg, Germany
| | - Estibaliz Mateo
- Biotecnología Enológica. Dept. Bioquímica i Biotecnologia, Facultat d'Enologia, Universitat Rovira i Virgili, C/Marcel.lí Domingo s/n., 43007, Tarragona, Spain. .,Departamento de Inmunología, Microbiología y Parasitología, Facultad de Medicina y Odontología, Universidad del País Vasco/Euskal Herriko Unibertsitatea UPV/EHU, Barrio Sarriena s/n., 48940, Leioa, Spain.
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Remote Control by Inter-Enzyme Allostery: A Novel Paradigm for Regulation of the Shikimate Pathway. J Mol Biol 2016; 428:1237-1255. [DOI: 10.1016/j.jmb.2016.01.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 12/22/2015] [Accepted: 01/02/2016] [Indexed: 11/16/2022]
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26
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Ma CW, Zhou LB, Zeng AP. Engineering Biomolecular Switches for Dynamic Metabolic Control. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 162:45-76. [DOI: 10.1007/10_2016_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Syal K, Joshi H, Chatterji D, Jain V. Novel pppGpp binding site at the C-terminal region of the Rel enzyme from Mycobacterium smegmatis. FEBS J 2015; 282:3773-85. [PMID: 26179484 DOI: 10.1111/febs.13373] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/26/2015] [Accepted: 07/09/2015] [Indexed: 11/28/2022]
Abstract
Mycobacterium tuberculosis elicits the stringent response under unfavorable growth conditions, such as those encountered by the pathogen inside the host. The hallmark of this response is production of guanosine tetra- and pentaphosphates, collectively termed (p)ppGpp, which have pleiotropic effects on the bacterial physiology. As the stringent response is connected to survival under stress, it is now being targeted for developing inhibitors against bacterial persistence. The Rel enzyme in mycobacteria has two catalytic domains at its N-terminus that are involved in the synthesis and hydrolysis of (p)ppGpp, respectively. However, the function of the C-terminal region of the protein remained unknown. Here, we have identified a binding site for pppGpp in the C-terminal region of Rel. The binding affinity of pppGpp was quantified by isothermal titration calorimetry. The binding site was determined by crosslinking using the nucleotide analog azido-pppGpp, and examining the crosslink product by mass spectrometry. Additionally, mutations in the Rel protein were created to confirm the site of pppGpp binding by isothermal titration calorimetry. These mutants showed increased pppGpp synthesis and reduced hydrolytic activity. We believe that binding of pppGpp to Rel provides a feedback mechanism that allows the protein to detect and adjust the (p)ppGpp level in the cell. Our work suggests that such sites should also be considered while designing inhibitors to target the stringent response.
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Affiliation(s)
- Kirtimaan Syal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Himanshu Joshi
- Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Vikas Jain
- Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
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Functional mapping of protein-protein interactions in an enzyme complex by directed evolution. PLoS One 2014; 9:e116234. [PMID: 25551646 PMCID: PMC4281200 DOI: 10.1371/journal.pone.0116234] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 12/06/2014] [Indexed: 11/19/2022] Open
Abstract
The shikimate pathway enzyme chorismate mutase converts chorismate into prephenate, a precursor of Tyr and Phe. The intracellular chorismate mutase (MtCM) of Mycobacterium tuberculosis is poorly active on its own, but becomes >100-fold more efficient upon formation of a complex with the first enzyme of the shikimate pathway, 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase (MtDS). The crystal structure of the enzyme complex revealed involvement of C-terminal MtCM residues with the MtDS interface. Here we employed evolutionary strategies to probe the tolerance to substitution of the C-terminal MtCM residues from positions 84–90. Variants with randomized positions were subjected to stringent selection in vivo requiring productive interactions with MtDS for survival. Sequence patterns identified in active library members coincide with residue conservation in natural chorismate mutases of the AroQδ subclass to which MtCM belongs. An Arg-Gly dyad at positions 85 and 86, invariant in AroQδ sequences, was intolerant to mutation, whereas Leu88 and Gly89 exhibited a preference for small and hydrophobic residues in functional MtCM-MtDS complexes. In the absence of MtDS, selection under relaxed conditions identifies positions 84–86 as MtCM integrity determinants, suggesting that the more C-terminal residues function in the activation by MtDS. Several MtCM variants, purified using a novel plasmid-based T7 RNA polymerase gene expression system, showed that a diminished ability to physically interact with MtDS correlates with reduced activatability and feedback regulatory control by Tyr and Phe. Mapping critical protein-protein interaction sites by evolutionary strategies may pinpoint promising targets for drugs that interfere with the activity of protein complexes.
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29
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Manjasetty BA, Chance MR, Burley SK, Panjikar S, Almo SC. Crystal structure of Clostridium acetobutylicum Aspartate kinase ( CaAK): An important allosteric enzyme for amino acids production. ACTA ACUST UNITED AC 2014; 3:73-85. [PMID: 25170437 PMCID: PMC4142519 DOI: 10.1016/j.btre.2014.06.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Aspartate kinase (AK) is an enzyme which is tightly regulated through feedback control and responsible for the synthesis of 4-phospho-l-aspartate from l-aspartate. This intermediate step is at an important branch point where one path leads to the synthesis of lysine and the other to threonine, methionine and isoleucine. Concerted feedback inhibition of AK is mediated by threonine and lysine and varies between the species. The crystal structure of biotechnologically important Clostridium acetobutylicum aspartate kinase (CaAK; E.C. 2.7.2.4; Mw = 48,030 Da; 437aa; SwissProt: Q97MC0) has been determined to 3 Å resolution. CaAK acquires a protein fold similar to the other known structures of AKs despite the low sequence identity (<30%). It is composed of two domains: an N-terminal catalytic domain (kinase domain) and a C-terminal regulatory domain further comprised of two small domains belonging to the ACT domain family. Pairwise comparison of 12 molecules in the asymmetric unit helped to identify the bending regions which are in the vicinity of ATP binding site involved in domain movements between the catalytic and regulatory domains. All 12 CaAK molecules adopt fully open T-state conformation leading to the formation of three tetramers unique among other similar AK structures. On the basis of comparative structural analysis, we discuss tetramer formation based on the large conformational changes in the catalytic domain associated with the lysine binding at the regulatory domains. The structure described herein is homologous to a target in wide-spread pathogenic (toxin producing) bacteria such as Clostridiumtetani (64% sequence identity) suggesting the potential of the structure solved here to be applied for modeling drug interactions. CaAK structure may serve as a guide to better understand and engineer lysine biosynthesis for the biotechnology industry.
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30
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Xu JY, You D, Leng PQ, Ye BC. Allosteric regulation of a protein acetyltransferase in Micromonospora aurantiaca by the amino acids cysteine and arginine. J Biol Chem 2014; 289:27034-27045. [PMID: 25124041 DOI: 10.1074/jbc.m114.579078] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ACT domains (amino acid-binding domains) are linked to a wide range of metabolic enzymes that are regulated by amino acid concentration. Seventy proteins with ACT-GCN5-related N-acetyltransferase (GNAT) domain organization were found in actinomycetales. In this study, we investigate the ACT-containing GNAT acetyltransferase, Micau_1670 (MaKat), from Micromonospora aurantiaca ATCC 27029. Arginine and cysteine were identified as ligands by monitoring the conformational changes that occur upon amino acids binding to the ACT domain in the MaKat protein using FRET assay. It was found that MaKat is an amino acid-regulated protein acetyltransferase, whereas arginine and cysteine stimulated the activity of MaKat with regard to acetylation of acetyl-CoA synthetase (Micau_0428). Our research reveals the biochemical characterization of a protein acetyltransferase that contains a fusion of a GNAT domain with an ACT domain and provides a novel signaling pathway for regulating cellular protein acetylation. These findings indicate that acetylation of proteins and acetyltransferase activity may be tightly linked to cellular concentrations of some amino acids in actinomycetales.
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Affiliation(s)
- Jun-Yu Xu
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Di You
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Pei-Qiang Leng
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Bang-Ce Ye
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.
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31
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Aghamirzaie D, Nabiyouni M, Fang Y, Klumas C, Heath LS, Grene R, Collakova E. Changes in RNA Splicing in Developing Soybean (Glycine max) Embryos. BIOLOGY 2013; 2:1311-37. [PMID: 24833227 PMCID: PMC4009788 DOI: 10.3390/biology2041311] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 11/06/2013] [Accepted: 11/12/2013] [Indexed: 12/17/2022]
Abstract
Developing soybean seeds accumulate oils, proteins, and carbohydrates that are used as oxidizable substrates providing metabolic precursors and energy during seed germination. The accumulation of these storage compounds in developing seeds is highly regulated at multiple levels, including at transcriptional and post-transcriptional regulation. RNA sequencing was used to provide comprehensive information about transcriptional and post-transcriptional events that take place in developing soybean embryos. Bioinformatics analyses lead to the identification of different classes of alternatively spliced isoforms and corresponding changes in their levels on a global scale during soybean embryo development. Alternative splicing was associated with transcripts involved in various metabolic and developmental processes, including central carbon and nitrogen metabolism, induction of maturation and dormancy, and splicing itself. Detailed examination of selected RNA isoforms revealed alterations in individual domains that could result in changes in subcellular localization of the resulting proteins, protein-protein and enzyme-substrate interactions, and regulation of protein activities. Different isoforms may play an important role in regulating developmental and metabolic processes occurring at different stages in developing oilseed embryos.
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Affiliation(s)
- Delasa Aghamirzaie
- Genetics, Bioinformatics and Computational Biology Program, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Mahdi Nabiyouni
- Department of Computer Science, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Yihui Fang
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Curtis Klumas
- Genetics, Bioinformatics and Computational Biology Program, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Lenwood S Heath
- Department of Computer Science, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Ruth Grene
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Eva Collakova
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.
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32
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Structural features of the regulatory ACT domain of phenylalanine hydroxylase. PLoS One 2013; 8:e79482. [PMID: 24244510 PMCID: PMC3828330 DOI: 10.1371/journal.pone.0079482] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 09/22/2013] [Indexed: 11/30/2022] Open
Abstract
Phenylalanine hydroxylase (PAH) catalyzes the conversion of L-Phe to L-Tyr. Defects in PAH activity, caused by mutations in the human gene, result in the autosomal recessively inherited disease hyperphenylalaninemia. PAH activity is regulated by multiple factors, including phosphorylation and ligand binding. In particular, PAH displays positive cooperativity for L-Phe, which is proposed to bind the enzyme on an allosteric site in the N-terminal regulatory domain (RD), also classified as an ACT domain. This domain is found in several proteins and is able to bind amino acids. We used molecular dynamics simulations to obtain dynamical and structural insights into the isolated RD of PAH. Here we show that the principal motions involve conformational changes leading from an initial open to a final closed domain structure. The global intrinsic motions of the RD are correlated with exposure to solvent of a hydrophobic surface, which corresponds to the ligand binding-site of the ACT domain. Our results strongly suggest a relationship between the Phe-binding function and the overall dynamic behaviour of the enzyme. This relationship may be affected by structure-disturbing mutations. To elucidate the functional implications of the mutations, we investigated the structural effects on the dynamics of the human RD PAH induced by six missense hyperphenylalaninemia-causing mutations, namely p.G46S, p.F39C, p.F39L, p.I65S, p.I65T and p.I65V. These studies showed that the alterations in RD hydrophobic interactions induced by missense mutations could affect the functionality of the whole enzyme.
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33
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Cross PJ, Parker EJ. Allosteric inhibitor specificity of Thermotoga maritima 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase. FEBS Lett 2013; 587:3063-8. [PMID: 23916814 DOI: 10.1016/j.febslet.2013.07.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 07/22/2013] [Accepted: 07/22/2013] [Indexed: 10/26/2022]
Abstract
3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAH7PS) catalyses the first step of the shikimate pathway for the biosynthesis of aromatic amino acids. Allosteric regulation of Thermotoga maritima DAH7PS is mediated by L-Tyr binding to a discrete ACT regulatory domain appended to a core catalytic (β/α)8 barrel. Variants of T. maritima DAH7PS (TmaDAH7PS) were created to probe the role of key residues in inhibitor selection. Substitution Ser31Gly severely reduced inhibition by L-Tyr. In contrast both L-Tyr and L-Phe inhibited the TmaHis29Ala variant, while the variant where Ser31 and His29 were interchanged (His29Ser/Ser31His), was inhibited to a greater extent by L-Phe than L-Tyr. These studies highlight the role and importance of His29 and Ser31 for determining both inhibitory ligand selectivity and the potency of allosteric response by TmaDAH7PS.
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Affiliation(s)
- Penelope J Cross
- Biomolecular Interaction Centre and Department of Chemistry, University of Canterbury, Christchurch, New Zealand
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34
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Flydal MI, Martinez A. Phenylalanine hydroxylase: function, structure, and regulation. IUBMB Life 2013; 65:341-9. [PMID: 23457044 DOI: 10.1002/iub.1150] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 01/09/2013] [Indexed: 11/08/2022]
Abstract
Mammalian phenylalanine hydroxylase (PAH) catalyzes the rate-limiting step in the phenylalanine catabolism, consuming about 75% of the phenylalanine input from the diet and protein catabolism under physiological conditions. In humans, mutations in the PAH gene lead to phenylketonuria (PKU), and most mutations are mainly associated with PAH misfolding and instability. The established treatment for PKU is a phenylalanine-restricted diet and, recently, supplementation with preparations of the natural tetrahydrobiopterin cofactor also shows effectiveness for some patients. Since 1997 there has been a significant increase in the understanding of the structure, catalytic mechanism, and regulation of PAH by its substrate and cofactor, in addition to improved correlations between genotype and phenotype in PKU. Importantly, there has also been an increased number of studies on the structure and function of PAH from bacteria and lower eukaryote organisms, revealing an additional anabolic role of the enzyme in the synthesis of melanin-like pigments. In this review, we discuss these recent studies, which contribute to define the evolutionary adaptation of the PAH structure and function leading to sophisticated regulation for effective catabolic processing of phenylalanine in mammalian organisms.
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Affiliation(s)
- Marte I Flydal
- Department of Biomedicine and K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Jonas Lies vei 91, 5009-Bergen, Norway
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35
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Jaffe EK, Stith L, Lawrence SH, Andrake M, Dunbrack RL. A new model for allosteric regulation of phenylalanine hydroxylase: implications for disease and therapeutics. Arch Biochem Biophys 2013; 530:73-82. [PMID: 23296088 PMCID: PMC3580015 DOI: 10.1016/j.abb.2012.12.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 12/07/2012] [Accepted: 12/19/2012] [Indexed: 02/06/2023]
Abstract
The structural basis for allosteric regulation of phenylalanine hydroxylase (PAH), whose dysfunction causes phenylketonuria (PKU), is poorly understood. A new morpheein model for PAH allostery is proposed to consist of a dissociative equilibrium between two architecturally different tetramers whose interconversion requires a ∼90° rotation between the PAH catalytic and regulatory domains, the latter of which contains an ACT domain. This unprecedented model is supported by in vitro data on purified full length rat and human PAH. The conformational change is both predicted to and shown to render the tetramers chromatographically separable using ion exchange methods. One novel aspect of the activated tetramer model is an allosteric phenylalanine binding site at the intersubunit interface of ACT domains. Amino acid ligand-stabilized ACT domain dimerization follows the multimerization and ligand binding behavior of ACT domains present in other proteins in the PDB. Spectroscopic, chromatographic, and electrophoretic methods demonstrate a PAH equilibrium consisting of two architecturally distinct tetramers as well as dimers. We postulate that PKU-associated mutations may shift the PAH quaternary structure equilibrium in favor of the low activity assemblies. Pharmacological chaperones that stabilize the ACT:ACT interface can potentially provide PKU patients with a novel small molecule therapeutic.
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Affiliation(s)
- Eileen K Jaffe
- Developmental Therapeutics, Institute for Cancer Research, Fox Chase Cancer Center, Temple Health, 333 Cottman Ave., Philadelphia, PA 19111, USA.
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36
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Engineering allosteric control to an unregulated enzyme by transfer of a regulatory domain. Proc Natl Acad Sci U S A 2013; 110:2111-6. [PMID: 23345433 DOI: 10.1073/pnas.1217923110] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Allosteric regulation of protein function is a critical component of metabolic control. Its importance is underpinned by the diversity of mechanisms and its presence in all three domains of life. The first enzyme of the aromatic amino acid biosynthesis, 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase, shows remarkable variation in allosteric response and machinery, and both contemporary regulated and unregulated orthologs have been described. To examine the molecular events by which allostery can evolve, we have generated a chimeric protein by joining the catalytic domain of an unregulated 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase with the regulatory domain of a regulated enzyme. We demonstrate that this simple gene fusion event on its own is sufficient to confer functional allostery to the unregulated enzyme. The fusion protein shares structural similarities with its regulated parent protein and undergoes an analogous major conformational change in response to the binding of allosteric effector tyrosine to the regulatory domain. These findings help delineate a remarkably facile mechanism for the evolution of modular allostery by domain recruitment.
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37
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Karanth NM, Sarma SP. The Coil-to-Helix Transition in IlvN Regulates the Allosteric Control of Escherichia coli Acetohydroxyacid Synthase I. Biochemistry 2012. [DOI: 10.1021/bi301415m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- N. Megha Karanth
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka,
India
| | - Siddhartha P. Sarma
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka,
India
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38
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Bitto E, Kim DJ, Bingman CA, Kim HJ, Han BW, Phillips GN. Crystal structure of tandem ACT domain-containing protein ACTP from Galdieria sulphuraria. Proteins 2012; 80:2105-2109. [PMID: 22528523 DOI: 10.1002/prot.24101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Revised: 04/13/2012] [Accepted: 04/17/2012] [Indexed: 11/09/2022]
Abstract
The ACT domain is a structurally conserved small molecule binding domain which is mostly involved in amino acid and purine metabolism. Here, we report the crystal structure of a tandem ACT domain-containing protein (ACTP) from Galdieria sulphuraria. The two ACTP monomers in the asymmetric unit form a dimer with a non-crystallographic twofold axis in a domain-swapped manner, showing a horseshoe-like structure with a central crevice. This structure contributes to expand our knowledge on the structural diversity of ACT domain-containing proteins.
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Affiliation(s)
- Eduard Bitto
- Department of Chemistry and Biochemistry, Georgian Court University, Lakewood, New Jersey 08701, USA
| | - Do Jin Kim
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Craig A Bingman
- Department of Biochemistry, Center for Eukaryotic Structural Genomics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Hyun-Jung Kim
- College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea
| | - Byung Woo Han
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - George N Phillips
- Department of Biochemistry, Center for Eukaryotic Structural Genomics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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39
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Fitzpatrick PF. Allosteric regulation of phenylalanine hydroxylase. Arch Biochem Biophys 2012; 519:194-201. [PMID: 22005392 PMCID: PMC3271142 DOI: 10.1016/j.abb.2011.09.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 09/27/2011] [Accepted: 09/28/2011] [Indexed: 10/16/2022]
Abstract
The liver enzyme phenylalanine hydroxylase is responsible for conversion of excess phenylalanine in the diet to tyrosine. Phenylalanine hydroxylase is activated by phenylalanine; this activation is inhibited by the physiological reducing substrate tetrahydrobiopterin. Phosphorylation of Ser16 lowers the concentration of phenylalanine for activation. This review discusses the present understanding of the molecular details of the allosteric regulation of the enzyme.
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Affiliation(s)
- Paul F Fitzpatrick
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, TX 78229-3900, USA.
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40
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Barak Z, Chipman DM. Allosteric regulation in Acetohydroxyacid Synthases (AHASs) – Different structures and kinetic behavior in isozymes in the same organisms. Arch Biochem Biophys 2012; 519:167-74. [DOI: 10.1016/j.abb.2011.11.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/25/2011] [Accepted: 11/29/2011] [Indexed: 10/14/2022]
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41
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Wang Y, Yi H, Wang M, Yu O, Jez JM. Structural and kinetic analysis of the unnatural fusion protein 4-coumaroyl-CoA ligase::stilbene synthase. J Am Chem Soc 2011; 133:20684-7. [PMID: 22129213 DOI: 10.1021/ja2085993] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
To increase the biochemical efficiency of biosynthetic systems, metabolic engineers have explored different approaches for organizing enzymes, including the generation of unnatural fusion proteins. Previous work aimed at improving the biosynthesis of resveratrol, a stilbene associated a range of health-promoting activities, in yeast used an unnatural engineered fusion protein of Arabidopsis thaliana (thale cress) 4-coumaroyl-CoA ligase (At4CL1) and Vitis vinifera (grape) stilbene synthase (VvSTS) to increase resveratrol levels 15-fold relative to yeast expressing the individual enzymes. Here we present the crystallographic and biochemical analysis of the 4CL::STS fusion protein. Determination of the X-ray crystal structure of 4CL::STS provides the first molecular view of an artificial didomain adenylation/ketosynthase fusion protein. Comparison of the steady-state kinetic properties of At4CL1, VvSTS, and 4CL::STS demonstrates that the fusion protein improves catalytic efficiency of either reaction less than 3-fold. Structural and kinetic analysis suggests that colocalization of the two enzyme active sites within 70 Å of each other provides the basis for enhanced in vivo synthesis of resveratrol.
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Affiliation(s)
- Yechun Wang
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, Missouri 63132, USA
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Walther DJ, Stahlberg S, Vowinckel J. Novel roles for biogenic monoamines: from monoamines in transglutaminase-mediated post-translational protein modification to monoaminylation deregulation diseases. FEBS J 2011; 278:4740-55. [DOI: 10.1111/j.1742-4658.2011.08347.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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A truncated form of SpoT, including the ACT domain, inhibits the production of cyclic lipopeptide arthrofactin, and is associated with moderate elevation of guanosine 3',5'-bispyrophosphate level in Pseudomonas sp. MIS38. Biosci Biotechnol Biochem 2011; 75:1880-8. [PMID: 21979063 DOI: 10.1271/bbb.110042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Arthrofactin is a biosurfactant produced by Pseudomonas sp. MIS38. We have reported that transposon insertion into spoT (spoT::Tn5) causes moderate accumulation of guanosine 3',5'-bispyrophosphate (ppGpp) and abrogates arthrofactin production. To analyze the linkage of SpoT function and ablation of arthrofactin production, we examined the spoT::Tn5 mutation. The results showed that spoT::Tn5 is not a null mutation, but encodes separate segments of SpoT. Deletion of the 3' region of spoT increased the level of arthrofactin production, suggesting that the C-terminal region of SpoT plays a suppressive role. We evaluated the expression of a distinct segment of SpoT. Forced expression of the C-terminal region that contains the ACT domain resulted in the accumulation of ppGpp and abrogated arthrofactin production. Expression of the C-terminal segment also reduced MIS38 swarming and resulted in extensive biofilm formation, which constitutes the phenocopy of the spoT::Tn5 mutant.
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Selective utilization of exogenous amino acids by Dehalococcoides ethenogenes strain 195 and its effects on growth and dechlorination activity. Appl Environ Microbiol 2011; 77:7797-803. [PMID: 21890673 DOI: 10.1128/aem.05676-11] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Bacteria of the genus Dehalococcoides are important members of bioremediation communities because of their ability to detoxify chloroethenes to the benign end product ethene. Genome-enabled studies conducted with Dehalococcoides ethenogenes 195 have revealed that two ATP-binding cassette (ABC)-type amino acid transporters are expressed during its exponential growth stages. In light of previous findings that Casamino Acids enhanced its dechlorination activity, we hypothesized that strain 195 is capable of importing amino acids from its environment to facilitate dechlorination and growth. To test this hypothesis, we applied isotopomer-based dilution analysis with (13)C-labeled acetate to differentiate the amino acids that were taken up by strain 195 from those synthesized de novo and to determine the physiological changes caused by the significantly incorporated amino acids. Our results showed that glutamate/glutamine and aspartate/asparagine were almost exclusively synthesized by strain 195, even when provided in excess in the medium. In contrast, phenylalanine, isoleucine, leucine, and methionine were identified as the four most highly incorporated amino acids, at levels >30% of respective proteinogenic amino acids. When either phenylalanine or all four highly incorporated amino acids were added to the defined mineral medium, the growth rates, dechlorination activities, and yields of strain 195 were enhanced to levels similar to those observed with supplementation with 20 amino acids. However, genes for the putative ABC-type amino acids transporters and phenylalanine biosynthesis exhibited insignificant regulation in response to the imported amino acids. This study also demonstrates that using isotopomer-based metabolite analysis can be an efficient strategy for optimizing nutritional conditions for slow-growing microorganisms.
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Sung TY, Chung TY, Hsu CP, Hsieh MH. The ACR11 encodes a novel type of chloroplastic ACT domain repeat protein that is coordinately expressed with GLN2 in Arabidopsis. BMC PLANT BIOLOGY 2011; 11:118. [PMID: 21861936 PMCID: PMC3173338 DOI: 10.1186/1471-2229-11-118] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 08/24/2011] [Indexed: 05/08/2023]
Abstract
BACKGROUND The ACT domain, named after bacterial aspartate kinase, chorismate mutase and TyrA (prephenate dehydrogenase), is a regulatory domain that serves as an amino acid-binding site in feedback-regulated amino acid metabolic enzymes. We have previously identified a novel type of ACT domain-containing protein family, the ACT domain repeat (ACR) protein family, in Arabidopsis. Members of the ACR family, ACR1 to ACR8, contain four copies of the ACT domain that extend throughout the entire polypeptide. Here, we describe the identification of four novel ACT domain-containing proteins, namely ACR9 to ACR12, in Arabidopsis. The ACR9 and ACR10 proteins contain three copies of the ACT domain, whereas the ACR11 and ACR12 proteins have a putative transit peptide followed by two copies of the ACT domain. The functions of these plant ACR proteins are largely unknown. RESULTS The ACR11 and ACR12 proteins are predicted to target to chloroplasts. We used protoplast transient expression assay to demonstrate that the Arabidopsis ACR11- and ACR12-green fluorescent fusion proteins are localized to the chloroplast. Analysis of an ACR11 promoter-β-glucuronidase (GUS) fusion in transgenic Arabidopsis revealed that the GUS activity was mainly detected in mature leaves and sepals. Interestingly, coexpression analysis revealed that the GLN2, which encodes a chloroplastic glutamine synthetase, has the highest mutual rank in the coexpressed gene network connected to ACR11. We used RNA gel blot analysis to confirm that the expression pattern of ACR11 is similar to that of GLN2 in various organs from 6-week-old Arabidopsis. Moreover, the expression of ACR11 and GLN2 is highly co-regulated by sucrose and light/dark treatments in 2-week-old Arabidopsis seedlings. CONCLUSIONS This study reports the identification of four novel ACT domain repeat proteins, ACR9 to ACR12, in Arabidopsis. The ACR11 and ACR12 proteins are localized to the chloroplast, and the expression of ACR11 and GLN2 is highly coordinated. These results suggest that the ACR11 and GLN2 genes may belong to the same functional module. The Arabidopsis ACR11 protein may function as a regulatory protein that is related to glutamine metabolism or signaling in the chloroplast.
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Affiliation(s)
- Tzu-Ying Sung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Tsui-Yun Chung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Chih-Ping Hsu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Ming-Hsiun Hsieh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
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Cross PJ, Dobson RCJ, Patchett ML, Parker EJ. Tyrosine latching of a regulatory gate affords allosteric control of aromatic amino acid biosynthesis. J Biol Chem 2011; 286:10216-24. [PMID: 21282100 DOI: 10.1074/jbc.m110.209924] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The first step of the shikimate pathway for aromatic amino acid biosynthesis is catalyzed by 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAH7PS). Thermotoga maritima DAH7PS (TmaDAH7PS) is tetrameric, with monomer units comprised of a core catalytic (β/α)(8) barrel and an N-terminal domain. This enzyme is inhibited strongly by tyrosine and to a lesser extent by the presence of phenylalanine. A truncated mutant of TmaDAH7PS lacking the N-terminal domain was catalytically more active and completely insensitive to tyrosine and phenylalanine, consistent with a role for this domain in allosteric inhibition. The structure of this protein was determined to 2.0 Å. In contrast to the wild-type enzyme, this enzyme is dimeric. Wild-type TmaDAH7PS was co-crystallized with tyrosine, and the structure of this complex was determined to a resolution of 2.35 Å. Tyrosine was found to bind at the interface between two regulatory N-terminal domains, formed from diagonally located monomers of the tetramer, revealing a major reorganization of the regulatory domain with respect to the barrel relative to unliganded enzyme. This significant conformational rearrangement observed in the crystal structures was also clearly evident from small angle X-ray scattering measurements recorded in the presence and absence of tyrosine. The closed conformation adopted by the protein on tyrosine binding impedes substrate entry into the neighboring barrel, revealing an unusual tyrosine-controlled gating mechanism for allosteric control of this enzyme.
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Affiliation(s)
- Penelope J Cross
- Biomolecular Interaction Centre, University of Canterbury, Christchurch 8040, New Zealand
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Li J, Ilangovan U, Daubner SC, Hinck AP, Fitzpatrick PF. Direct evidence for a phenylalanine site in the regulatory domain of phenylalanine hydroxylase. Arch Biochem Biophys 2010; 505:250-5. [PMID: 20951114 DOI: 10.1016/j.abb.2010.10.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 10/05/2010] [Accepted: 10/11/2010] [Indexed: 10/18/2022]
Abstract
The hydroxylation of phenylalanine to tyrosine by the liver enzyme phenylalanine hydroxylase is regulated by the level of phenylalanine. Whether there is a distinct allosteric binding site for phenylalanine outside of the active site has been unclear. The enzyme contains an N-terminal regulatory domain that extends through Thr117. The regulatory domain of rat phenylalanine hydroxylase was expressed in Escherichia coli. The purified protein behaves as a dimer on a gel filtration column. In the presence of phenylalanine, the protein elutes earlier from the column, consistent with a conformational change in the presence of the amino acid. No change in elution is seen in the presence of the non-activating amino acid proline. ¹H-¹⁵N HSQC NMR spectra were obtained of the ¹⁵N-labeled protein alone and in the presence of phenylalanine or proline. A subset of the peaks in the spectrum exhibits chemical shift perturbation in the presence of phenylalanine, consistent with binding of phenylalanine at a specific site. No change in the NMR spectrum is seen in the presence of proline. These results establish that the regulatory domain of phenylalanine hydroxylase can bind phenylalanine, consistent with the presence of an allosteric site for the amino acid.
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Affiliation(s)
- Jun Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, 77843-2128, United States
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Li J, Dangott LJ, Fitzpatrick PF. Regulation of phenylalanine hydroxylase: conformational changes upon phenylalanine binding detected by hydrogen/deuterium exchange and mass spectrometry. Biochemistry 2010; 49:3327-35. [PMID: 20307070 DOI: 10.1021/bi1001294] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Phenylalanine acts as an allosteric activator of the tetrahydropterin-dependent enzyme phenylalanine hydroxylase. Hydrogen/deuterium exchange monitored by mass spectrometry has been used to gain insight into local conformational changes accompanying activation of rat phenylalanine hydroxylase by phenylalanine. Peptides in the regulatory and catalytic domains that lie in the interface between these two domains show large increases in the extent of deuterium incorporation from solvent in the presence of phenylalanine. In contrast, the effects of phenylalanine on the exchange kinetics of a mutant enzyme lacking the regulatory domain are limited to peptides surrounding the binding site for the amino acid substrate. These results support a model in which the N-terminus of the protein acts as an inhibitory peptide, with phenylalanine binding causing a conformational change in the regulatory domain that alters the interaction between the catalytic and regulatory domains.
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Affiliation(s)
- Jun Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station,Texas 77843-2128, USA
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Cohesion group approach for evolutionary analysis of aspartokinase, an enzyme that feeds a branched network of many biochemical pathways. Microbiol Mol Biol Rev 2010; 73:594-651. [PMID: 19946135 DOI: 10.1128/mmbr.00024-09] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aspartokinase (Ask) exists within a variable network that supports the synthesis of 9 amino acids and a number of other important metabolites. Lysine, isoleucine, aromatic amino acids, and dipicolinate may arise from the ASK network or from alternative pathways. Ask proteins were subjected to cohesion group analysis, a methodology that sorts a given protein assemblage into groups in which evolutionary continuity is assured. Two subhomology divisions, ASK(alpha) and ASK(beta), have been recognized. The ASK(alpha) subhomology division is the most ancient, being widely distributed throughout the Archaea and Eukarya and in some Bacteria. Within an indel region of about 75 amino acids near the N terminus, ASK(beta) sequences differ from ASK(alpha) sequences by the possession of a proposed ancient deletion. ASK(beta) sequences are present in most Bacteria and usually exhibit an in-frame internal translational start site that can generate a small Ask subunit that is identical to the C-terminal portion of the larger subunit of a heterodimeric unit. Particularly novel are ask genes embedded in gene contexts that imply specialization for ectoine (osmotic agent) or aromatic amino acids. The cohesion group approach is well suited for the easy recognition of relatively recent lateral gene transfer (LGT) events, and many examples of these are described. Given the current density of genome representation for Proteobacteria, it is possible to reconstruct more ancient landmark LGT events. Thus, a plausible scenario in which the three well-studied and iconic Ask homologs of Escherichia coli are not within the vertical genealogy of Gammaproteobacteria, but rather originated via LGT from a Bacteroidetes donor, is supported.
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Exploring the molecular basis for selective binding of Mycobacterium tuberculosis Asp kinase toward its natural substrates and feedback inhibitors: a docking and molecular dynamics study. J Mol Model 2010; 16:1357-67. [PMID: 20140471 DOI: 10.1007/s00894-010-0653-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 01/05/2010] [Indexed: 10/19/2022]
Abstract
Tuberculosis (TB) is still a major public health problem, compounded by the human immunodeficiency virus (HIV)-TB co-infection and recent emergence of multidrug-resistant (MDR) and extensively drug resistant (XDR)-TB. In this context, aspartokinase of mycobacterium tuberculosis has drawn attention for designing novel anti-TB drugs. Asp kinase is an enzyme responsible for the synthesis of 4-phospho-L-aspartate from L-aspartate and involved in the branched biosynthetic pathway leading to the synthesis of amino acids lysine, threonine, methionine and isoleucine. An intermediate of lysine biosynthetic branch, mesodiaminopimelate is also a component of the peptidoglycan which is a component of bacterial cell wall. To interfere with the production of all these amino acids and cell wall, it is possible to inhibit Asp kinase activity. This can be achieved using Asp kinase inhibitors. In order to design novel Asp kinase inhibitors as effective anti-TB drugs, it is necessary to have an understanding of the binding sites of Asp kinase. As no crystal structure of the enzyme has yet been published, we built a homology model of Asp kinase using the crystallized Asp kinase from M. Jannaschii, as template structures (2HMF and 3C1M). After the molecular dynamics refinement, the optimized homology model was assessed as a reliable structure by PROCHECK, ERRAT, WHAT-IF, PROSA2003 and VERIFY-3D. The results of molecular docking studies with natural substrates, products and feedback inhibitors are in agreement with the published data and showed that ACT domain plays an important role in binding to ligands. Based on the docking conformations, pharmacophore model can be developed by probing the common features of ligands. By analyzing the results, ACT domain architecture, certain key residues that are responsible for binding to feedback inhibitors and natural substrates were identified. This would be very helpful in understanding the blockade mechanism of Asp kinase and providing insights into rational design of novel Asp kinase inhibitors for M.tuberculosis.
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