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Naz S, Liu P, Farooq U, Ma H. Insight into de-regulation of amino acid feedback inhibition: a focus on structure analysis method. Microb Cell Fact 2023; 22:161. [PMID: 37612753 PMCID: PMC10464499 DOI: 10.1186/s12934-023-02178-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 08/13/2023] [Indexed: 08/25/2023] Open
Abstract
Regulation of amino acid's biosynthetic pathway is of significant importance to maintain homeostasis and cell functions. Amino acids regulate their biosynthetic pathway by end-product feedback inhibition of enzymes catalyzing committed steps of a pathway. Discovery of new feedback resistant enzyme variants to enhance industrial production of amino acids is a key objective in industrial biotechnology. Deregulation of feedback inhibition has been achieved for various enzymes using in vitro and in silico mutagenesis techniques. As enzyme's function, its substrate binding capacity, catalysis activity, regulation and stability are dependent on its structural characteristics, here, we provide detailed structural analysis of all feedback sensitive enzyme targets in amino acid biosynthetic pathways. Current review summarizes information regarding structural characteristics of various enzyme targets and effect of mutations on their structures and functions especially in terms of deregulation of feedback inhibition. Furthermore, applicability of various experimental as well as computational mutagenesis techniques to accomplish feedback resistance has also been discussed in detail to have an insight into various aspects of research work reported in this particular field of study.
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Affiliation(s)
- Sadia Naz
- Biodesign Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Pi Liu
- Biodesign Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Umar Farooq
- Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, Islamabad, 22060, Pakistan
| | - Hongwu Ma
- Biodesign Center, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
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2
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Wang J, Sheng Z, Liu Y, Chen X, Wang S, Yang H. Combined proteomic and transcriptomic analysis of the antimicrobial mechanism of tannic acid against Staphylococcus aureus. Front Pharmacol 2023; 14:1178177. [PMID: 37654613 PMCID: PMC10466393 DOI: 10.3389/fphar.2023.1178177] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 08/01/2023] [Indexed: 09/02/2023] Open
Abstract
Staphylococcus aureus is a zoonotic opportunistic pathogen that represents a significant threat to public health. Previous studies have shown that tannic acid (TA) has an inhibitory effect on a variety of bacteria. In this study, the proteome and transcriptome of S. aureus were analyzed to comprehensively assess changes in genes and proteins induced by TA. Initial observations of morphological changes revealed that TA damaged the integrity of the cell membrane. Next, proteomic and genetic analyses showed that exposure to TA altered the expression levels of 651 differentially expressed proteins (DEPs, 283 upregulated and 368 downregulated) and 503 differentially expressed genes (DEGs, 191 upregulated and 312 downregulated). Analysis of the identified DEPs and DEGs suggested that TA damages the integrity of the cell envelope by decreasing the expression and protein abundance of enzymes involved in the synthesis of peptidoglycans, teichoic acids and fatty acids, such as murB, murQ, murG, fmhX and tagA. After treatment with TA, the assembly of ribosomes in S. aureus was severely impaired by significant reductions in available ribosome components, and thus protein synthesis was hindered. The levels of genes and proteins associated with amino acids and purine synthesis were remarkably decreased, which further reduced bacterial viability. In addition, ABC transporters, which are involved in amino acid and ion transport, were also badly affected. Our results reveal the molecular mechanisms underlying the effects of TA on S. aureus and provide a theoretical basis for the application of TA as an antibacterial chemotherapeutic agent.
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Affiliation(s)
- Jing Wang
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, Jiangsu Province, China
| | - Zhicun Sheng
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, Jiangsu Province, China
| | - Yunying Liu
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, Jiangsu Province, China
- Zhongchong Sino Biotech Taizhou Co., Ltd., Taizhou, Jiangsu Province, China
| | - Xiaolan Chen
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, Jiangsu Province, China
| | - Shuaibing Wang
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, Jiangsu Province, China
| | - Haifeng Yang
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, Jiangsu Province, China
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3
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Ciulla DA, Xu Z, Pezzullo JL, Dranchak P, Wang C, Giner JL, Inglese J, Callahan BP. Paracatalytic induction: Subverting specificity in hedgehog protein autoprocessing with small molecules. Methods Enzymol 2023; 685:1-41. [PMID: 37245899 PMCID: PMC10294009 DOI: 10.1016/bs.mie.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Paracatalytic inducers are antagonists that shift the specificity of biological catalysts, resulting in non-native transformations. In this Chapter we describe methods to discover paracatalytic inducers of Hedgehog (Hh) protein autoprocessing. Native autoprocessing uses cholesterol as a substrate nucleophile to assist in cleaving an internal peptide bond within a precursor form of Hh. This unusual reaction is brought about by HhC, an enzymatic domain that resides within the C-terminal region of Hh precursor proteins. Recently, we reported paracatalytic inducers as a novel class of Hh autoprocessing antagonists. These small molecules bind HhC and tilt the substrate specificity away from cholesterol in favor of solvent water. The resulting cholesterol-independent autoproteolysis of the Hh precursor generates a non-native Hh side product with substantially reduced biological signaling activity. Protocols are provided for in vitro FRET-based and in-cell bioluminescence assays to discover and characterize paracatalytic inducers of Drosophila and human hedgehog protein autoprocessing, respectively.
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Affiliation(s)
- Daniel A Ciulla
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, United States.
| | - Zihan Xu
- Chemistry Department, Binghamton University, Binghamton, NY, United States
| | - John L Pezzullo
- State University of New York, College of Environmental Science and Forestry, Syracuse, NY, United States
| | - Patricia Dranchak
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, United States
| | - Chunyu Wang
- Department of Biological Sciences, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - José-Luis Giner
- State University of New York, College of Environmental Science and Forestry, Syracuse, NY, United States
| | - James Inglese
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, United States; National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States
| | - Brian P Callahan
- Chemistry Department, Binghamton University, Binghamton, NY, United States
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4
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Copley SD, Newton MS, Widney KA. How to Recruit a Promiscuous Enzyme to Serve a New Function. Biochemistry 2023; 62:300-308. [PMID: 35729117 PMCID: PMC9881647 DOI: 10.1021/acs.biochem.2c00249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Promiscuous enzymes can be recruited to serve new functions when a genetic or environmental change makes catalysis of a novel reaction important for fitness or even survival. Subsequently, gene duplication and divergence can lead to evolution of an efficient and specialized new enzyme. Every organism likely has thousands of promiscuous enzyme activities that provide a vast reservoir of catalytic potential. However, much of this potential may not be accessible. We compiled kinetic parameters for promiscuous reactions catalyzed by 108 enzymes. The median value of kcat/KM is a very modest 31 M-1 s-1. Based upon the fluxes through metabolic pathways in E. coli, we estimate that many, if not most, promiscuous activities are too inefficient to impact fitness. However, mutations can elevate the level of an insufficient promiscuous activity by increasing enzyme expression, improving kcat/KM, or altering concentrations of the promiscuous and native substrates and allosteric regulators. Particularly in large bacterial populations, stochastic mutations may provide a viable pathway for recruitment of even inefficient promiscuous activities.
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5
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Yadav J, Singh H, Pal SK, Das S, Srivastava VK, Jyoti A, Sharma V, Kumar S, Kaushik S. Exploring the molecular interaction of Pheniramine with Enterococcus faecalis Homoserine Kinase: In-silico and in vitro studies. J Mol Recognit 2022; 35:e2979. [PMID: 35642097 DOI: 10.1002/jmr.2979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 05/03/2022] [Accepted: 05/26/2022] [Indexed: 11/07/2022]
Abstract
Infections caused by the bacteria Enterococcus faecalis (also known as E. faecalis) are common in hospitals. This bacterium is resistant to a wide range of medicines and causes a variety of nosocomial infections. An increase in the number of infections caused by multidrug-resistant (MDR) bacteria is causing substantial economic and health issues around the world. Consequently, new therapeutic techniques to tackle the growing threat of E. faecalis infections must be developed as soon as possible. In this regard, we have targeted a protein that is regarded to be critical for the survival of bacteria in this experiment. Homoserine kinase (HSK) is a threonine metabolism enzyme that belongs to the GHMP kinase superfamily. It is a crucial enzyme in threonine metabolism. This enzyme is responsible for a critical step in the threonine biosynthesis pathway. Given the important function that E. faecalis Homoserine Kinase (ESK) plays in bacterial metabolism, we proposed that E. faecalis HSK be cloned, overexpressed, purified, and subjected to structural analyses using homology modelling. In addition, we have reported on the model's molecular docking and Molecular Dynamic Stimulation (MD Stimulation) investigations to validate the results of the docking experiments. The results were promising. In silico investigations came up with the conclusion: pheniramine has good binding affinity for the E. faecalis HSK.
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Affiliation(s)
- Jyoti Yadav
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Harpreet Singh
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Sudhir Kumar Pal
- Centre for Bioseparation Technology, VIT University, Vellore, India
| | - Satyajeet Das
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | | | - Anupam Jyoti
- Department of Biotechnology, University Institute of Biotechnology, Chandigarh University, Chandigarh, India
| | - Vinay Sharma
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Sanjit Kumar
- Centre for Bioseparation Technology, VIT University, Vellore, India
| | - Sanket Kaushik
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
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6
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Meshram RJ, Shirsath A, Aouti S, Bagul K, Gacche RN. Molecular modeling and simulation study of homoserine kinase as an effective leishmanial drug target. J Mol Model 2020; 26:218. [PMID: 32720228 DOI: 10.1007/s00894-020-04473-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 07/14/2020] [Indexed: 11/25/2022]
Abstract
Leishmaniasis is a tropical neglected disease that imposes major health concerns in many endemic countries worldwide and requires urgent attention to the identification of new drug targets as well as drug candidates. In the current study, we propose homoserine kinase (HSK) inhibition as a strategy to induce pathogen mortality via generating threonine deficiency. We introduce a homology-based molecular model of leishmanial HSK that appears to possess all conserved structural as well as functional features in the GHMP kinase family. Furthermore, 200 ns molecular dynamics data of the enzyme in open and closed state attempts to provide the mechanistic details involved in the substrate as well as phosphate binding to this enzyme. We discuss the structural and functional significance of movements involved in various loops (motif 1, 2, 3) and lips (upper and lower) in the transition of leishmanial HSK from closed to open state. Virtual screening data of more than 40,000 compounds from the present investigation tries to identify a few potential HSK inhibitors that possess important features to act as efficient HSK inhibitors. These compounds can be considered an effective starting point for the identification of novel drug-like scaffolds. We hope the structural wealth that is offered in this report will be utilized in designing competent experimental and therapeutic interventions for leishmaniasis management. Graphical abstract.
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Affiliation(s)
- Rohan J Meshram
- Bioinformatics Centre, Savitribai Phule Pune University, Pune, Maharashtra, 411007, India.
| | - Akshay Shirsath
- Bioinformatics Centre, Savitribai Phule Pune University, Pune, Maharashtra, 411007, India
| | - Snehal Aouti
- Bioinformatics Centre, Savitribai Phule Pune University, Pune, Maharashtra, 411007, India
| | - Kamini Bagul
- Bioinformatics Centre, Savitribai Phule Pune University, Pune, Maharashtra, 411007, India
| | - Rajesh N Gacche
- Department of Biotechnology, Savitribai Phule Pune University, Pune, Maharashtra, 411007, India
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7
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Prabhavathi P, Rajendran R, Karthiksundaram S, Pattabi S, Dinesh Kumar S, Santhanam P. Enhanced bioremediation efficiency of denim industrial effluent using bacterial biofilm onto polyurethane matrix (review). APPL BIOCHEM MICRO+ 2014. [DOI: 10.1134/s0003683814060131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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8
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Velyvis A, Ruschak AM, Kay LE. An economical method for production of (2)H, (13)CH3-threonine for solution NMR studies of large protein complexes: application to the 670 kDa proteasome. PLoS One 2012; 7:e43725. [PMID: 22984438 PMCID: PMC3439479 DOI: 10.1371/journal.pone.0043725] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/24/2012] [Indexed: 11/26/2022] Open
Abstract
NMR studies of very high molecular weight protein complexes have been greatly facilitated through the development of labeling strategies whereby 13CH3 methyl groups are introduced into highly deuterated proteins. Robust and cost-effective labeling methods are well established for all methyl containing amino acids with the exception of Thr. Here we describe an inexpensive biosynthetic strategy for the production of L-[α-2H; β−2H;γ-13C]-Thr that can then be directly added during protein expression to produce highly deuterated proteins with Thr methyl group probes of structure and dynamics. These reporters are particularly valuable, because unlike other methyl containing amino acids, Thr residues are localized predominantly to the surfaces of proteins, have unique hydrogen bonding capabilities, have a higher propensity to be found at protein nucleic acid interfaces and can play important roles in signaling pathways through phosphorylation. The utility of the labeling methodology is demonstrated with an application to the 670 kDa proteasome core particle, where high quality Thr 13C,1H correlation spectra are obtained that could not be generated from samples prepared with commercially available U-[13C,1H]-Thr.
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Affiliation(s)
- Algirdas Velyvis
- Departments of Molecular Genetics, Biochemistry, and Chemistry, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (AV); (LEK)
| | - Amy M. Ruschak
- Departments of Molecular Genetics, Biochemistry, and Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Lewis E. Kay
- Departments of Molecular Genetics, Biochemistry, and Chemistry, University of Toronto, Toronto, Ontario, Canada
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada
- * E-mail: (AV); (LEK)
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9
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The role of the active site residues in human galactokinase: implications for the mechanisms of GHMP kinases. Bioorg Chem 2011; 39:120-6. [PMID: 21474160 DOI: 10.1016/j.bioorg.2011.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 03/01/2011] [Accepted: 03/02/2011] [Indexed: 11/20/2022]
Abstract
Galactokinase catalyses the phosphorylation of galactose at the expense of ATP. Like other members of the GHMP family of kinases it is postulated to function through an active site base mechanism in which Asp-186 abstracts a proton from galactose. This asparate residue was altered to alanine and to asparagine by site-directed mutagenesis of the corresponding gene. This resulted in variant enzyme with no detectable galactokinase activity. Alteration of Arg-37, which lies adjacent to Asp-186 and is postulated to assist the catalytic base, to lysine resulted in an active enzyme. However, alteration of this residue to glutamate abolished activity. All the variant enzymes, except the arginine to lysine substitution, were structurally unstable (as judged by native gel electrophoresis in the presence of urea) compared to the wild type. This suggests that the lack of activity results from this structural instability, in addition to any direct effects on the catalytic mechanism. Computational estimations of the pK(a) values of the arginine and aspartate residues, suggest that Arg-37 remains protonated throughout the catalytic cycle whereas Asp-186 has an abnormally high pK(a) value (7.18). Quantum mechanics/molecular mechanics (QM/MM) calculations suggest that Asp-186 moves closer to the galactose molecule during catalysis. The experimental and theoretical studies presented here argue for a mechanism in which the C(1)-OH bond in the sugar is weakened by the presence of Asp-186 thus facilitating nucleophilic attack by the oxygen atom on the γ-phosphorus of ATP.
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10
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Chen M, Poulter CD. Characterization of thermophilic archaeal isopentenyl phosphate kinases. Biochemistry 2010; 49:207-17. [PMID: 19928876 DOI: 10.1021/bi9017957] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Archaea synthesize isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the essential building blocks of isoprenoid compounds, from mevalonate (MVA). However, an analysis of the genomes of several members of the Archaea failed to identify genes for the enzymes required to convert phosphomevalonate (PM) to IPP in eukaryotes. The recent discovery of an isopentenyl kinase (IPK) in Methanocaldococcus jannaschii (MJ) suggests a new variation of the MVA pathway where PM is decarboxylated to give isopentenyl phosphate (IP), which is phosphorylated to produce IPP. A blast search using the MJ protein as a probe revealed a subfamily of amino acid kinases that include the fosfomycin resistance protein fomA, which deactivates the antibiotic by phosphorylation of its phosphonate residue in a reaction similar to the conversion of IP to IPP. IPK genes were cloned from two organisms identified in the search, Methanothermobacter thermautotrophicus (MTH) and Thermoplasma acidophilum (THA), and the His-tagged recombinant proteins were purified by Ni-NTA chromatography. The enzymes catalyze the reversible phosphorylation of IP by ATP, K(eq) = 6.3 +/- 1. The catalytic efficiencies (V/K) of the proteins were approximately 2 x 10(6) M(-1) s(-1). In the reverse direction, ADP was a substrate inhibitor for THA IPK, K(i)(ADP) = 58 +/- 6 microM, but not for MTH IPK. Both enzymes were active over a broad range of pH and temperature. Five compounds, dimethylallyl phosphate, isopentenyl thiolophosphate, 1-butyl phosphate, 3-buten-1-yl phosphate, and geranyl phosphate, were evaluated as alternative substrates for the MTH and THA IP kinases. All of the compounds were phosphorylated, although the catalytic efficiency was low for geranyl phosphate.
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Affiliation(s)
- Mo Chen
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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11
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Fan C, Fromm HJ, Bobik TA. Kinetic and functional analysis of L-threonine kinase, the PduX enzyme of Salmonella enterica. J Biol Chem 2009; 284:20240-8. [PMID: 19509296 DOI: 10.1074/jbc.m109.027425] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PduX enzyme of Salmonella enterica is an l-threonine kinase used for the de novo synthesis of coenzyme B(12) and the assimilation of cobyric acid. PduX with an N-terminal histidine tag (His(8)-PduX) was produced in Escherichiacoli and purified. The recombinant enzyme was soluble and active. Kinetic analysis indicated a steady-state Ordered Bi Bi complex mechanism in which ATP is the first substrate to bind. Based on a multiple sequence alignment of PduX homologues and other GHMP (galactokinase, homoserine kinase, mevalonate kinase, and phosphomevalonate kinase) family members, 14 PduX variants having changes at 10 conserved serine/threonine and aspartate/glutamate sites were constructed by site-directed mutagenesis. Each variant was produced in E. coli and purified. Comparison of the circular dichroism spectra and kinetic properties of the PduX variants with those of the wild-type enzyme indicated that Glu-24 and Asp-135 are needed for proper folding, Ser-99 and Glu-132 are used for ATP binding, and Ser-253 and Ser-255 are critical to l-threonine binding whereas Ser-100 is essential to catalysis, but its precise role is uncertain. The studies reported here are the first to investigate the kinetic and catalytic mechanisms of l-threonine kinase from any organism.
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Affiliation(s)
- Chenguang Fan
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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12
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Bareich DC, Wright GD. Functionally important amino acids in Saccharomyces cerevisiae aspartate kinase. Biochem Biophys Res Commun 2003; 311:597-603. [PMID: 14623312 DOI: 10.1016/j.bbrc.2003.10.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Saccharomyces cerevisiae aspartate kinase (AK(Sc)) phosphorylates L-Asp as the first step in the aspartate pathway responsible for the biosynthesis of L-Thr, L-Met, and L-Ile in microorganisms and plants. Using site-directed mutagenesis, we have evaluated the importance of residues in AK(Sc) that are strongly conserved among aspartate kinases or in other small molecule kinases. Steady state kinetic analysis of the purified AK(Sc) variants reveals that several of the targeted amino acids, particularly K18 and H292, have important roles in the enzymatic reaction. These results provide the first identification of amino acid residues crucial to the action of this important metabolic enzyme.
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Affiliation(s)
- David C Bareich
- Department of Biochemistry, McMaster University, 1200 Main St, W, Hamilton, Ont, Canada L8N 3Z5
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13
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Daugherty M, Vonstein V, Overbeek R, Osterman A. Archaeal shikimate kinase, a new member of the GHMP-kinase family. J Bacteriol 2001; 183:292-300. [PMID: 11114929 PMCID: PMC94878 DOI: 10.1128/jb.183.1.292-300.2001] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shikimate kinase (EC 2.7.1.71) is a committed enzyme in the seven-step biosynthesis of chorismate, a major precursor of aromatic amino acids and many other aromatic compounds. Genes for all enzymes of the chorismate pathway except shikimate kinase are found in archaeal genomes by sequence homology to their bacterial counterparts. In this study, a conserved archaeal gene (gi1500322 in Methanococcus jannaschii) was identified as the best candidate for the missing shikimate kinase gene by the analysis of chromosomal clustering of chorismate biosynthetic genes. The encoded hypothetical protein, with no sequence similarity to bacterial and eukaryotic shikimate kinases, is distantly related to homoserine kinases (EC 2.7.1.39) of the GHMP-kinase superfamily. The latter functionality in M. jannaschii is assigned to another gene (gi591748), in agreement with sequence similarity and chromosomal clustering analysis. Both archaeal proteins, overexpressed in Escherichia coli and purified to homogeneity, displayed activity of the predicted type, with steady-state kinetic parameters similar to those of the corresponding bacterial kinases: K(m,shikimate) = 414 +/- 33 microM, K(m,ATP) = 48 +/- 4 microM, and k(cat) = 57 +/- 2 s(-1) for the predicted shikimate kinase and K(m,homoserine) = 188 +/- 37 microM, K(m,ATP) = 101 +/- 7 microM, and k(cat) = 28 +/- 1 s(-1) for the homoserine kinase. No overlapping activity could be detected between shikimate kinase and homoserine kinase, both revealing a >1,000-fold preference for their own specific substrates. The case of archaeal shikimate kinase illustrates the efficacy of techniques based on reconstruction of metabolism from genomic data and analysis of gene clustering on chromosomes in finding missing genes.
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Affiliation(s)
- M Daugherty
- Integrated Genomics Inc., Chicago, Illinois 60612, USA
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14
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Metzler DE, Metzler CM, Sauke DJ. The Metabolism of Nitrogen and Amino Acids. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50027-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Zhou T, Daugherty M, Grishin NV, Osterman AL, Zhang H. Structure and mechanism of homoserine kinase: prototype for the GHMP kinase superfamily. Structure 2000; 8:1247-57. [PMID: 11188689 DOI: 10.1016/s0969-2126(00)00533-5] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Homoserine kinase (HSK) catalyzes an important step in the threonine biosynthesis pathway. It belongs to a large yet unique class of small metabolite kinases, the GHMP kinase superfamily. Members in the GHMP superfamily participate in several essential metabolic pathways, such as amino acid biosynthesis, galactose metabolism, and the mevalonate pathway. RESULTS The crystal structure of HSK and its complex with ADP reveal a novel nucleotide binding fold. The N-terminal domain contains an unusual left-handed betaalphabeta unit, while the C-terminal domain has a central alpha-beta plait fold with an insertion of four helices. The phosphate binding loop in HSK is distinct from the classical P loops found in many ATP/GTP binding proteins. The bound ADP molecule adopts a rare syn conformation and is in the opposite orientation from those bound to the P loop-containing proteins. Inspection of the substrate binding cavity indicates several amino acid residues that are likely to be involved in substrate binding and catalysis. CONCLUSIONS The crystal structure of HSK is the first representative in the GHMP superfamily to have determined structure. It provides insight into the structure and nucleotide binding mechanism of not only the HSK family but also a variety of enzymes in the GHMP superfamily. Such enzymes include galactokinases, mevalonate kinases, phosphomevalonate kinases, mevalonate pyrophosphate decarboxylases, and several proteins of yet unknown functions.
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Affiliation(s)
- T Zhou
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75390, USA
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16
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Lee M, Leustek T. Identification of the gene encoding homoserine kinase from Arabidopsis thaliana and characterization of the recombinant enzyme derived from the gene. Arch Biochem Biophys 1999; 372:135-42. [PMID: 10562426 DOI: 10.1006/abbi.1999.1481] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Homoserine kinase (EC 2.7.1.39) catalyzes the formation of O-phospho-l-homoserine, a branch point intermediate in the pathways for Met and Thr in plants. A genomic open reading frame located on the top arm of chromosome II and a corresponding cDNA have been identified from Arabidopsis thaliana that encode homoserine kinase. The HSK gene is composed of an 1113-bp continuous open reading frame that could produce a 38-kDa protein. The gene product has homology with homoserine kinase from bacteria and fungi. It contains a conserved motif, known as GHMP, found in a group of ATP-dependent metabolite kinases and thought to comprise the ATP binding site. The amino-terminal 50 amino acids of the HSK protein show features of a transit peptide for localization to plastids. Genomic blot analysis revealed that there is a single locus in A. thaliana to which the HSK cDNA hybridizes. The HSK protein expressed as a His-tagged construct in Escherichia coli shows a specific activity in an l-homoserine-dependent ADP synthesis assay of 3.09 +/- 0.25 micromol min(-1) mg(-1) protein at pH 8.5 and 37 degrees C. The apparent K(m) values are 0.40 mM for l-homoserine and 0.32 mM for Mg-ATP. Other hydroxylated compounds are not used as substrates. The enzyme requires 40 mM K(+) and 3 mM Mg(2+) for activity. It has an unusually high temperature optimum, yet it is very unstable, losing more than 80% of its activity after a single cycle of freeze-thawing. The HSK enzyme shows no significant regulation by amino acids in vitro.
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Affiliation(s)
- M Lee
- Biotechnology Center for Agriculture and the Environment and the Plant Science Department, Rutgers University, New Brunswick, New Jersey, 08901-8520, USA
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