1
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Malakar B, Chauhan K, Sanyal P, Naz S, Kalam H, Vivek-Ananth RP, Singh LV, Samal A, Kumar D, Nandicoori VK. Phosphorylation of CFP10 modulates Mycobacterium tuberculosis virulence. mBio 2023; 14:e0123223. [PMID: 37791794 PMCID: PMC10653824 DOI: 10.1128/mbio.01232-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 07/25/2023] [Indexed: 10/05/2023] Open
Abstract
IMPORTANCE Secreted virulence factors play a critical role in bacterial pathogenesis. Virulence effectors not only help bacteria to overcome the host immune system but also aid in establishing infection. Mtb, which causes tuberculosis in humans, encodes various virulence effectors. Triggers that modulate the secretion of virulence effectors in Mtb are yet to be fully understood. To gain mechanistic insight into the secretion of virulence effectors, we performed high-throughput proteomic studies. With the help of system-level protein-protein interaction network analysis and empirical validations, we unravelled a link between phosphorylation and secretion. Taking the example of the well-known virulence factor of CFP10, we show that the dynamics of CFP10 phosphorylation strongly influenced bacterial virulence and survival ex vivo and in vivo. This study presents the role of phosphorylation in modulating the secretion of virulence factors.
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Affiliation(s)
- Basanti Malakar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Komal Chauhan
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Priyadarshini Sanyal
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Centre for Cellular and Molecular Biology Campus, Hyderabad, India
| | - Saba Naz
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Haroon Kalam
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - R. P. Vivek-Ananth
- The Institute of Mathematical Sciences (IMSc), Homi Bhabha National Institute (HBNI), Chennai, India
| | - Lakshya Veer Singh
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Areejit Samal
- The Institute of Mathematical Sciences (IMSc), Homi Bhabha National Institute (HBNI), Chennai, India
| | - Dhiraj Kumar
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Vinay Kumar Nandicoori
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Centre for Cellular and Molecular Biology Campus, Hyderabad, India
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2
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Soni V, Rosenn EH, Venkataraman R. Insights into the central role of N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmU) in peptidoglycan metabolism and its potential as a therapeutic target. Biochem J 2023; 480:1147-1164. [PMID: 37498748 DOI: 10.1042/bcj20230173] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/07/2023] [Accepted: 07/14/2023] [Indexed: 07/29/2023]
Abstract
Several decades after the discovery of the first antibiotic (penicillin) microbes have evolved novel mechanisms of resistance; endangering not only our abilities to combat future bacterial pandemics but many other clinical challenges such as acquired infections during surgeries. Antimicrobial resistance (AMR) is attributed to the mismanagement and overuse of these medications and is complicated by a slower rate of the discovery of novel drugs and targets. Bacterial peptidoglycan (PG), a three-dimensional mesh of glycan units, is the foundation of the cell wall that protects bacteria against environmental insults. A significant percentage of drugs target PG, however, these have been rendered ineffective due to growing drug resistance. Identifying novel druggable targets is, therefore, imperative. Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) is one of the key building blocks in PG production, biosynthesized by the bifunctional enzyme N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmU). UDP-GlcNAc metabolism has been studied in many organisms, but it holds some distinctive features in bacteria, especially regarding the bacterial GlmU enzyme. In this review, we provide an overview of different steps in PG biogenesis, discuss the biochemistry of GlmU, and summarize the characteristic structural elements of bacterial GlmU vital to its catalytic function. Finally, we will discuss various studies on the development of GlmU inhibitors and their significance in aiding future drug discoveries.
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Affiliation(s)
- Vijay Soni
- Division of Infectious Diseases, Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10065, U.S.A
| | - Eric H Rosenn
- Tel Aviv University School of Medicine, Tel Aviv 6997801, Israel
| | - Ramya Venkataraman
- Laboratory of Innate Immunity, National Institute of Immunology, New Delhi 110067, India
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3
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Han X, Chen C, Wang H, Kang J, Yan Q, Ma Y, Wang W, Wu S, Wang C, Ma X. GlmU inhibitor from the roots of Euphorbia ebracteolata as an anti-tuberculosis agent. RSC Adv 2022; 12:18266-18273. [PMID: 35800323 PMCID: PMC9214920 DOI: 10.1039/d2ra02044k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 06/16/2022] [Indexed: 11/21/2022] Open
Abstract
Ebractenoid F was identified to be a GlmU inhibitor from Euphorbia ebracteolata, which could inhibit the cell wall biosynthesis of M. tb H37Ra, along with the biofilm formation.
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Affiliation(s)
- Xiuyan Han
- Second Affiliated Hospital, Institute of Integrative Medicine, Dalian Medical University, Dalian 116023, P.R. of China
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Changming Chen
- Department of Rheumatology and Immunology, The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang 550001, P.R. of China
| | - Honglei Wang
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Jian Kang
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Qiulong Yan
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Yufang Ma
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Wenxin Wang
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Shan Wu
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Chao Wang
- Second Affiliated Hospital, Institute of Integrative Medicine, Dalian Medical University, Dalian 116023, P.R. of China
- College of Pharmacy, Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, P.R. of China
| | - Xiaochi Ma
- Second Affiliated Hospital, Institute of Integrative Medicine, Dalian Medical University, Dalian 116023, P.R. of China
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4
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Subedi BP, Martin WF, Carbone V, Duin EC, Cronin B, Sauter J, Schofield LR, Sutherland-Smith AJ, Ronimus RS. Archaeal pseudomurein and bacterial murein cell wall biosynthesis share a common evolutionary ancestry. FEMS MICROBES 2021; 2:xtab012. [PMID: 37334239 PMCID: PMC10117817 DOI: 10.1093/femsmc/xtab012] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 08/19/2021] [Indexed: 08/29/2023] Open
Abstract
Bacteria near-universally contain a cell wall sacculus of murein (peptidoglycan), the synthesis of which has been intensively studied for over 50 years. In striking contrast, archaeal species possess a variety of other cell wall types, none of them closely resembling murein. Interestingly though, one type of archaeal cell wall termed pseudomurein found in the methanogen orders Methanobacteriales and Methanopyrales is a structural analogue of murein in that it contains a glycan backbone that is cross-linked by a L-amino acid peptide. Here, we present taxonomic distribution, gene cluster and phylogenetic analyses that confirm orthologues of 13 bacterial murein biosynthesis enzymes in pseudomurein-containing methanogens, most of which are distantly related to their bacterial counterparts. We also present the first structure of an archaeal pseudomurein peptide ligase from Methanothermus fervidus DSM1088 (Mfer336) to a resolution of 2.5 Å and show that it possesses a similar overall tertiary three domain structure to bacterial MurC and MurD type murein peptide ligases. Taken together the data strongly indicate that murein and pseudomurein biosynthetic pathways share a common evolutionary history.
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Affiliation(s)
- Bishwa P Subedi
- AgResearch Ltd. Grasslands, Tennent Drive, Palmerston North 4442, New Zealand
- Massey University, Tennent Drive, Palmerston North 4442, New Zealand
| | - William F Martin
- Institute for Molecular Evolution, Heinrich-Heine University, Düsseldorf Universitätsstraße 1, D-40225, Germany
| | - Vincenzo Carbone
- AgResearch Ltd. Grasslands, Tennent Drive, Palmerston North 4442, New Zealand
| | - Eduardus C Duin
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA
| | - Bryan Cronin
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA
| | - Julia Sauter
- AgResearch Ltd. Grasslands, Tennent Drive, Palmerston North 4442, New Zealand
| | - Linley R Schofield
- AgResearch Ltd. Grasslands, Tennent Drive, Palmerston North 4442, New Zealand
| | | | - Ron S Ronimus
- AgResearch Ltd. Grasslands, Tennent Drive, Palmerston North 4442, New Zealand
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5
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Unique C-terminal extension and interactome of Mycobacterium tuberculosis GlmU impacts it's in vivo function and the survival of pathogen. Biochem J 2021; 478:2081-2099. [PMID: 33955473 DOI: 10.1042/bcj20210170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/01/2021] [Accepted: 05/06/2021] [Indexed: 11/17/2022]
Abstract
N-acetyl glucosamine-1-phosphate uridyltransferase (GlmU) is a bifunctional enzyme involved in the biosynthesis of Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). UDP-GlcNAc is a critical precursor for the synthesis of peptidoglycan and other cell wall components. The absence of a homolog in eukaryotes makes GlmU an attractive target for therapeutic intervention. Mycobacterium tuberculosis GlmU (GlmUMt) has features, such as a C-terminal extension, that are not present in GlmUorthologs from other bacteria. Here, we set out to determine the uniqueness of GlmUMt by performing in vivo complementation experiments using RvΔglmU mutant. We find that any deletion of the carboxy-terminal extension region of GlmUMt abolishes its ability to complement the function of GlmUMt. Results show orthologs of GlmU, including its closest ortholog, from Mycobacterium smegmatis, cannot complement the function of GlmUMt. Furthermore, the co-expression of GlmUMt domain deletion mutants with either acetyl or uridyltransferase activities failed to rescue the function. However, co-expression of GlmUMt point mutants with either acetyl or uridyltransferase activities successfully restored the biological function of GlmUMt, likely due to the formation of heterotrimers. Based on the interactome experiments, we speculate that GlmUMt participates in unique interactions essential for its in vivo function.
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6
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Sachla AJ, Helmann JD. Resource sharing between central metabolism and cell envelope synthesis. Curr Opin Microbiol 2021; 60:34-43. [PMID: 33581378 PMCID: PMC7988295 DOI: 10.1016/j.mib.2021.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 01/18/2021] [Accepted: 01/27/2021] [Indexed: 12/14/2022]
Abstract
Synthesis of the bacterial cell envelope requires a regulated partitioning of resources from central metabolism. Here, we consider the key metabolic junctions that provide the precursors needed to assemble the cell envelope. Peptidoglycan synthesis requires redirection of a glycolytic intermediate, fructose-6-phosphate, into aminosugar biosynthesis by the highly regulated branchpoint enzyme GlmS. MurA directs the downstream product, UDP-GlcNAc, specifically into peptidoglycan synthesis. Other shared resources required for cell envelope synthesis include the isoprenoid carrier lipid undecaprenyl phosphate and amino acids required for peptidoglycan cross-bridges. Assembly of the envelope requires a sharing of limited resources between competing cellular pathways and may additionally benefit from scavenging of metabolites released from neighboring cells or the formation of symbiotic relationships with a host.
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Affiliation(s)
- Ankita J Sachla
- Department of Microbiology, Cornell University, 370 Wing Hall, Wing Drive, Ithaca, NY 14853-8101, USA
| | - John D Helmann
- Department of Microbiology, Cornell University, 370 Wing Hall, Wing Drive, Ithaca, NY 14853-8101, USA.
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7
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Maitra A, Munshi T, Healy J, Martin LT, Vollmer W, Keep NH, Bhakta S. Cell wall peptidoglycan in Mycobacterium tuberculosis: An Achilles' heel for the TB-causing pathogen. FEMS Microbiol Rev 2020; 43:548-575. [PMID: 31183501 PMCID: PMC6736417 DOI: 10.1093/femsre/fuz016] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/07/2019] [Indexed: 02/06/2023] Open
Abstract
Tuberculosis (TB), caused by the intracellular pathogen Mycobacterium tuberculosis, remains one of the leading causes of mortality across the world. There is an urgent requirement to build a robust arsenal of effective antimicrobials, targeting novel molecular mechanisms to overcome the challenges posed by the increase of antibiotic resistance in TB. Mycobacterium tuberculosis has a unique cell envelope structure and composition, containing a peptidoglycan layer that is essential for maintaining cellular integrity and for virulence. The enzymes involved in the biosynthesis, degradation, remodelling and recycling of peptidoglycan have resurfaced as attractive targets for anti-infective drug discovery. Here, we review the importance of peptidoglycan, including the structure, function and regulation of key enzymes involved in its metabolism. We also discuss known inhibitors of ATP-dependent Mur ligases, and discuss the potential for the development of pan-enzyme inhibitors targeting multiple Mur ligases.
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Affiliation(s)
- Arundhati Maitra
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Tulika Munshi
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Jess Healy
- Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Liam T Martin
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Waldemar Vollmer
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Nicholas H Keep
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Sanjib Bhakta
- Mycobacteria Research Laboratory, Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
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8
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Design, properties and applications of fluorinated and fluoroalkylated N-containing monosaccharides and their analogues. J Fluor Chem 2019. [DOI: 10.1016/j.jfluchem.2019.109364] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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9
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Bais VS, Batra S, Prakash B. Identification of two highly promiscuous thermostable sugar nucleotidylyltransferases for glycorandomization. FEBS J 2018; 285:2840-2855. [PMID: 29806742 DOI: 10.1111/febs.14521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 04/14/2018] [Accepted: 05/23/2018] [Indexed: 01/22/2023]
Abstract
Glycorandomization is a process that improves the efficacy of glycoconjugates by the addition of a diverse array of sugars to secondary metabolites and antibiotics of pharmaceutical importance. This process, which employs sugar nucleotidylyltransferases (SNTs) and glycosyl transferases (GTs) in tandem, would benefit by the employment of promiscuous enzymes, i.e. those with the ability to utilize diverse noncanonical substrates. As promiscuous GTs are available, here we set out to identify promiscuous SNTs. For this, we began with a detailed family-wide characterization of SNTs. Earlier, we had proposed that SNTs could be classified into two major groups - I and II. They share a common structural framework and utilize a similar catalytic mechanism. Subtle variations in the way two magnesium ions - MgA2+ and MgB2+ - are stabilized by metal ion coordination motifs led to their classification into diverse subgroups viz. I-A, I-B, I-C, II-A, and II-B. Based on this classification, here we investigate promiscuity across the entire family of SNTs. We study the utilization of several sugar phosphates and nucleotides by the various subgroups of SNTs to understand substrate specificity and promiscuity in these. We find that promiscuity is prevalent among SNTs; and in particular, in the thermophilic homologs. In principle, promiscuity profiling identified four new SNTs that can be employed for the production of sugar-nucleotide libraries. However, assaying for their ability to simultaneously utilize multiple substrates in a single-pot reaction, we find two thermophilic SNTs- TMGA , an adenylyltransferase from Thermotoga maritima and PHGT , a thymidylyltransferase from Pyrococcus horikoshii that are readily employable for the production of diverse sugar-nucleotides.
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Affiliation(s)
- Vaibhav Singh Bais
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
| | - Sahil Batra
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
| | - Balaji Prakash
- Department of Molecular Nutrition, CSIR-Central Food Technological Research Institute, Mysore, India
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10
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Craggs PD, Mouilleron S, Rejzek M, de Chiara C, Young RJ, Field RA, Argyrou A, de Carvalho LPS. The Mechanism of Acetyl Transfer Catalyzed by Mycobacterium tuberculosis GlmU. Biochemistry 2018; 57:3387-3401. [PMID: 29684272 PMCID: PMC6011181 DOI: 10.1021/acs.biochem.8b00121] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biosynthetic pathway of peptidoglycan is essential for Mycobacterium tuberculosis. We report here the acetyltransferase substrate specificity and catalytic mechanism of the bifunctional N-acetyltransferase/uridylyltransferase from M. tuberculosis (GlmU). This enzyme is responsible for the final two steps of the synthesis of UDP- N-acetylglucosamine, which is an essential precursor of peptidoglycan, from glucosamine 1-phosphate, acetyl-coenzyme A, and uridine 5'-triphosphate. GlmU utilizes ternary complex formation to transfer an acetyl from acetyl-coenzyme A to glucosamine 1-phosphate to form N-acetylglucosamine 1-phosphate. Steady-state kinetic studies and equilibrium binding experiments indicate that GlmU follows a steady-state ordered kinetic mechanism, with acetyl-coenzyme A binding first, which triggers a conformational change in GlmU, followed by glucosamine 1-phosphate binding. Coenzyme A is the last product to dissociate. Chemistry is partially rate-limiting as indicated by pH-rate studies and solvent kinetic isotope effects. A novel crystal structure of a mimic of the Michaelis complex, with glucose 1-phosphate and acetyl-coenzyme A, helps us to propose the residues involved in deprotonation of glucosamine 1-phosphate and the loop movement that likely generates the active site required for glucosamine 1-phosphate to bind. Together, these results pave the way for the rational discovery of improved inhibitors against M. tuberculosis GlmU, some of which might become candidates for antibiotic discovery programs.
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Affiliation(s)
- Peter D Craggs
- Platform Technology and Science , GlaxoSmithKline , Stevenage , U.K
| | | | | | | | - Robert J Young
- Platform Technology and Science , GlaxoSmithKline , Stevenage , U.K
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11
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UDP-GlcNAc pathway: Potential target for inhibitor discovery against M. tuberculosis. Eur J Pharm Sci 2016; 83:62-70. [DOI: 10.1016/j.ejps.2015.12.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/29/2015] [Accepted: 12/08/2015] [Indexed: 11/23/2022]
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12
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Sharma R, Lambu MR, Jamwal U, Rani C, Chib R, Wazir P, Mukherjee D, Chaubey A, Khan IA. Escherichia coli N-Acetylglucosamine-1-Phosphate-Uridyltransferase/Glucosamine-1-Phosphate-Acetyltransferase (GlmU) Inhibitory Activity of Terreic Acid Isolated from Aspergillus terreus. ACTA ACUST UNITED AC 2016; 21:342-53. [PMID: 26762501 DOI: 10.1177/1087057115625308] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/19/2015] [Indexed: 11/16/2022]
Abstract
Secondary metabolite of Aspergillus terreus, terreic acid, is a reported potent antibacterial that was identified more than 60 years ago, but its cellular target(s) are still unknown. Here we screen its activity against the acetyltransferase domain of a bifunctional enzyme, Escherichia coli N-acetylglucosamine-1-phosphate-uridyltransferase/glucosamine-1-phosphate-acetyltransferase (GlmU). An absorbance-based assay was used to screen terreic acid against the acetyltransferase activity of E. coli GlmU. Terreic acid was found to inhibit the acetyltransferase domain of E. coli GlmU with an IC50 of 44.24 ± 1.85 µM. Mode of inhibition studies revealed that terreic acid was competitive with AcCoA and uncompetitive with GlcN-1-P. It also exhibited concentration-dependent killing of E. coli ATCC 25922 up to 4× minimum inhibitory concentration and inhibited the growth of biofilms generated by E. coli. Characterization of resistant mutants established mutation in the acetyltransferase domain of GlmU. Terreic acid was also found to be metabolically stable in the in vitro incubations with rat liver microsome in the presence of a NADPH regenerating system. The studies reported here suggest that terreic acid is a potent antimicrobial agent and support that E. coli GlmU acetyltransferase is a molecular target of terreic acid, resulting in its antibacterial activity.
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Affiliation(s)
- Rashmi Sharma
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, India Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, India
| | - Mallikharjuna Rao Lambu
- Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, India Natural Products Chemistry: Microbes, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu, India
| | - Urmila Jamwal
- Fermentation Technology Division, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu Tawi, India
| | - Chitra Rani
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, India Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, India
| | - Reena Chib
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, India
| | - Priya Wazir
- Instrumentation Division, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu Tawi, India
| | - Debaraj Mukherjee
- Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, India Natural Products Chemistry: Microbes, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu, India
| | - Asha Chaubey
- Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, India Fermentation Technology Division, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu Tawi, India
| | - Inshad Ali Khan
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, India Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, India
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13
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Sharma R, Rani C, Mehra R, Nargotra A, Chib R, Rajput VS, Kumar S, Singh S, Sharma PR, Khan IA. Identification and characterization of novel small molecule inhibitors of the acetyltransferase activity of Escherichia coli N-acetylglucosamine-1-phosphate-uridyltransferase/glucosamine-1-phosphate-acetyltransferase (GlmU). Appl Microbiol Biotechnol 2015; 100:3071-85. [PMID: 26563552 DOI: 10.1007/s00253-015-7123-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/19/2015] [Accepted: 10/26/2015] [Indexed: 10/22/2022]
Abstract
This study aims at identifying novel chemical scaffolds as inhibitors specific to the acetyltransferase domain of a bifunctional enzyme, Escherichia coli GlmU, involved in the cell wall biosynthesis of Gram-negative organisms. A two-pronged approach was used to screen a 50,000 small-molecule library. Using the first approach, the library was in silico screened by docking the library against acetyltransferase domain of E. coli GlmU studies. In the second approach, complete library was screened against Escherichia coli ATCC 25922 to identify the whole cell active compounds. Active compounds from both the screens were screened in a colorimetric absorbance-based assay to identify inhibitors of acetyltransferase domain of E. coli GlmU which resulted in the identification of 1 inhibitor out of 56 hits identified by in silico screening and 4 inhibitors out of 35 whole cell active compounds on Gram-negative bacteria with the most potent inhibitor showing IC50 of 1.40 ± 0.69 μM. Mode of inhibition studies revealed these inhibitors to be competitive with AcCoA and uncompetitive with GlcN-1-P. These selected inhibitors were also tested for their antibacterial and cytotoxic activities. Compounds 5175178 and 5215319 exhibited antibacterial activity that co-related with GlmU inhibition. These compounds, therefore, represent novel chemical scaffolds targeting acetyltransferase activity of E. coli GlmU.
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Affiliation(s)
- Rashmi Sharma
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, 180001, India.,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Chitra Rani
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, 180001, India.,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Rukmankesh Mehra
- Discovery Informatics Division, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu, 180001, India
| | - Amit Nargotra
- Discovery Informatics Division, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu, 180001, India.,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Reena Chib
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, 180001, India
| | - Vikrant S Rajput
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, 180001, India.,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Sunil Kumar
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, 180001, India.,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Samsher Singh
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, 180001, India.,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Parduman R Sharma
- Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu Tawi, 180001, India.,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India
| | - Inshad A Khan
- Clinical Microbiology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi, 180001, India. .,Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu, 180001, India.
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14
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Soni V, Upadhayay S, Suryadevara P, Samla G, Singh A, Yogeeswari P, Sriram D, Nandicoori VK. Depletion of M. tuberculosis GlmU from Infected Murine Lungs Effects the Clearance of the Pathogen. PLoS Pathog 2015; 11:e1005235. [PMID: 26489015 PMCID: PMC4619583 DOI: 10.1371/journal.ppat.1005235] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/27/2015] [Indexed: 01/06/2023] Open
Abstract
M. tuberculosis N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmUMtb) is a bi-functional enzyme engaged in the synthesis of two metabolic intermediates N-acetylglucosamine-1-phosphate (GlcNAc-1-P) and UDP-GlcNAc, catalyzed by the C- and N-terminal domains respectively. UDP-GlcNAc is a key metabolite essential for the synthesis of peptidoglycan, disaccharide linker, arabinogalactan and mycothiols. While glmUMtb was predicted to be an essential gene, till date the role of GlmUMtb in modulating the in vitro growth of Mtb or its role in survival of pathogen ex vivo / in vivo have not been deciphered. Here we present the results of a comprehensive study dissecting the role of GlmUMtb in arbitrating the survival of the pathogen both in vitro and in vivo. We find that absence of GlmUMtb leads to extensive perturbation of bacterial morphology and substantial reduction in cell wall thickness under normoxic as well as hypoxic conditions. Complementation studies show that the acetyl- and uridyl- transferase activities of GlmUMtb are independently essential for bacterial survival in vitro, and GlmUMtb is also found to be essential for mycobacterial survival in THP-1 cells as well as in guinea pigs. Depletion of GlmUMtb from infected murine lungs, four weeks post infection, led to significant reduction in the bacillary load. The administration of Oxa33, a novel oxazolidine derivative that specifically inhibits GlmUMtb, to infected mice resulted in significant decrease in the bacillary load. Thus our study establishes GlmUMtb as a strong candidate for intervention measures against established tuberculosis infections. The synthesis of the Mtb cell wall involves a cascade of reactions catalyzed by cytosolic and cell membrane-bound enzymes. The reaction catalyzed by GlmUMtb (an enzyme with acetyltransferase and uridyltransferase activities) generates UDP-GlcNAc, a central nucleotide-sugar building block of the cell wall. Apart from cell wall synthesis UDP-GlcNAc is an essential metabolite participating in other cellular processes including disaccharide linker and mycothiol biosynthesis. GlmUMtb shares very little sequence similarity with eukaryotic acetyltransferase and uridyltransferase enzymes. Many pathogens have alternative pathway(s) for foraging GlcNAc from the host. The present study was undertaken to see the effects of depleting GlmUMtb on pathogen survival in the host animal. We have generated a conditional gene replacement mutant of glmUMtb and find that depletion of GlmUMtb at any stage of bacterial growth or in mice infected with Mtb including a well-established infection, results in irreversible bacterial death due to perturbation of cell wall synthesis. We have developed a novel anti-GlmUMtb inhibitor (Oxa33), identified its binding site on GlmUMtb, and shown its specificity for GlmUMtb. The study demonstrates that GlmUMtb is a promising target for therapeutic intervention and Oxa33 can be pursued as a lead molecule.
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Affiliation(s)
- Vijay Soni
- National Institute of Immunology, New Delhi, India
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | | | - Priyanka Suryadevara
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Ganesh Samla
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Archana Singh
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Perumal Yogeeswari
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Dharmarajan Sriram
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
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15
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Manuse S, Fleurie A, Zucchini L, Lesterlin C, Grangeasse C. Role of eukaryotic-like serine/threonine kinases in bacterial cell division and morphogenesis. FEMS Microbiol Rev 2015; 40:41-56. [DOI: 10.1093/femsre/fuv041] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2015] [Indexed: 11/14/2022] Open
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16
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Soni V, Suryadevara P, Sriram D, Kumar S, Nandicoori VK, Yogeeswari P. Structure-based design of diverse inhibitors of Mycobacterium tuberculosis N-acetylglucosamine-1-phosphate uridyltransferase: combined molecular docking, dynamic simulation, and biological activity. J Mol Model 2015; 21:174. [PMID: 26078037 DOI: 10.1007/s00894-015-2704-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 05/17/2015] [Indexed: 10/23/2022]
Abstract
Persistent nature of Mycobacterium tuberculosis is one of the major factors which make the drug development process monotonous against this organism. The highly lipophilic cell wall, which constituting outer mycolic acid and inner peptidoglycan layers, acts as a barrier for the drugs to enter the bacteria. The rigidity of the cell wall is imparted by the peptidoglycan layer, which is covalently linked to mycolic acid by arabinogalactan. Uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) serves as the starting material in the biosynthesis of this peptidoglycan layers. This UDP-GlcNAc is synthesized by N-acetylglucosamine-1-phosphate uridyltransferase (GlmU(Mtb)), a bi-functional enzyme with two functional sites, acetyltransferase site and uridyltransferase site. Here, we report design and screening of nine inhibitors against UTP and NAcGlc-1-P of uridyltransferase active site of glmU(Mtb). Compound 4 was showing good inhibition and was selected for further analysis. The isothermal titration calorimetry (ITC) experiments showed the binding energy pattern of compound 4 to the uridyltransferase active site is similar to that of substrate UTP. In silico molecular dynamics (MD) simulation studies, for compound 4, carried out for 10 ns showed the protein-compound complex to be stable throughout the simulation with relative rmsd in acceptable range. Hence, these compounds can serve as a starting point in the drug discovery processes against Mycobacterium tuberculosis.
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Affiliation(s)
- Vijay Soni
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad campus, Shameerpet, Jawahar Nagar, R.R. District, India
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17
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Alderwick LJ, Harrison J, Lloyd GS, Birch HL. The Mycobacterial Cell Wall--Peptidoglycan and Arabinogalactan. Cold Spring Harb Perspect Med 2015; 5:a021113. [PMID: 25818664 DOI: 10.1101/cshperspect.a021113] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The mycobacterial bacillus is encompassed by a remarkably elaborate cell wall structure. The mycolyl-arabinogalactan-peptidoglycan (mAGP) complex is essential for the viability of Mycobacterium tuberculosis and maintains a robust basal structure supporting the upper "myco-membrane." M. tuberculosis peptidoglycan, although appearing to be unexceptional at first glance, contains a number of unique molecular subtleties that become particularly important as the TB-bacilli enters into nonreplicative growth during dormancy. Arabinogalactan, a highly branched polysaccharide, serves to connect peptidoglycan with the outer mycolic acid layer, and a variety of unique glycolsyltransferases are used for its assembly. In this review, we shall explore the microbial chemistry of this unique heteropolysacchride, examine the molecular genetics that underpins its fabrication, and discuss how the essential biosynthetic process might be exploited for the development of future anti-TB chemotherapies.
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Affiliation(s)
- Luke J Alderwick
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - James Harrison
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Georgina S Lloyd
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Helen L Birch
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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18
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Zhang Z, Shimizu Y, Kawarabayasi Y. Characterization of the amino acid residues mediating the unique amino-sugar-1-phosphate acetyltransferase activity of the archaeal ST0452 protein. Extremophiles 2015; 19:417-27. [PMID: 25567746 DOI: 10.1007/s00792-014-0727-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 12/12/2014] [Indexed: 10/24/2022]
Abstract
The ST0452 protein from the thermophilic archaean Sulfolobus tokodaii has been identified as an enzyme with multiple sugar-1-phosphate nucleotidylyltransferase and amino-sugar-1-phosphate acetyltransferase (amino-sugar-1-P AcTase) activities. Analysis of the protein showed that in addition to glucosamine-1-phosphate (GlcN-1-P) AcTase activity, it possesses unique galactosamine-1-phosphate (GalN-1-P) AcTase activity not detected in any other proteins. Comparison of the crystal structures of the ST0452 protein and GlmU from Escherichia coli (EcGlmU), which possesses only GlcN-1-P AcTase activity, showed that the overall sequence identity between these two proteins is less than 25 %, but the amino acid residues predicted to comprise the catalytic center of EcGlmU are conserved in the ST0452 protein. To understand the molecular mechanism by which the ST0452 amino-sugar-1-P AcTase activity recognizes two independent substrates, several ST0452 substitution and truncation mutant proteins were constructed and analyzed. We found that His308 is essential for both GalN-1-P and GlcN-1-P AcTase activities, whereas Tyr311 and Asn331 are important only for the GalN-1-P AcTase activity. In addition, deletion of the C-terminal 5 or 11 residues showed that the 11-residue C-terminal region exerts a modest stimulatory effect on GalN-1-P AcTase activity but dramatically suppresses GlcN-1-P AcTase activity. This region also appears to make an important contribution to the thermostability of the entire ST0452 protein. Systematic deletions from the C-terminus also demonstrated that the C-terminal region with the β-helix structure has an important role mediating the trimerization of the ST0452 protein. This is the first report of an analysis of a thermostable archaeal enzyme exhibiting multiple amino-sugar-1-P AcTase activities.
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Affiliation(s)
- Zilian Zhang
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen, 361005, People's Republic of China
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19
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Purification and biochemical characterisation of GlmU from Yersinia pestis. Arch Microbiol 2014; 197:371-8. [PMID: 25417006 DOI: 10.1007/s00203-014-1065-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 11/12/2014] [Accepted: 11/16/2014] [Indexed: 12/22/2022]
Abstract
Antibiotic resistance has emerged as a real threat to mankind, rendering many compounds ineffective in the fight against bacterial infection, including for significant diseases such as plague caused by Yersinia pestis. Essential genes have been identified as promising targets for inhibiting with new classes of compounds. Previously, the gene encoding the bifunctional UDP-N-acetylglucosamine pyrophosphorylase/glucosamine-1-phosphate N-acetyltransferase enzyme GlmU was confirmed as an essential gene in Yersinia. As a step towards exploiting this target for antimicrobial screening, we undertook a biochemical characterisation of the Yersinia GlmU. Effects of pH and magnesium concentration on the acetyltransferase and uridyltransferase activities were analysed, and kinetic parameters were determined. The acetyltransferase activity, which is strongly increased in the presence of reducing agent, was shown to be susceptible to oxidation and thiol-specific reagents.
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20
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Rajanala K, Sarkar A, Jhingan GD, Priyadarshini R, Jalan M, Sengupta S, Nandicoori VK. Phosphorylation of nucleoporin Tpr governs its differential localization and is required for its mitotic function. J Cell Sci 2014; 127:3505-20. [PMID: 24938596 DOI: 10.1242/jcs.149112] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
A major constituent of the nuclear basket region of the nuclear pore complex (NPC), nucleoporin Tpr, plays roles in regulating multiple important processes. We have previously established that Tpr is phosphorylated in both a MAP-kinase-dependent and MAP-kinase-independent manner, and that Tpr acts as both a substrate and as a scaffold for ERK2 (also known as MAPK1). Here, we report the identification of S2059 and S2094 as the major novel ERK-independent phosphorylation sites and T1677, S2020, S2023 and S2034 as additional ERK-independent phosphorylation sites found in the Tpr protein in vivo. Our results suggest that protein kinase A phosphorylates the S2094 residue and that the site is hyperphosphorylated during mitosis. Furthermore, we find that Tpr is phosphorylated at the S2059 residue by CDK1 and the phosphorylated form distinctly localizes with chromatin during telophase. Abrogation of S2059 phosphorylation abolishes the interaction of Tpr with Mad1, thus compromising the localization of both Mad1 and Mad2 proteins, resulting in cell cycle defects. The identification of novel phosphorylation sites on Tpr and the observations presented in this study allow better understanding of Tpr functions.
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Affiliation(s)
- Kalpana Rajanala
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Anshuk Sarkar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Gagan Deep Jhingan
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Raina Priyadarshini
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Manisha Jalan
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Sagar Sengupta
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
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21
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Vithani N, Bais V, Prakash B. GlmU (N-acetylglucosamine-1-phosphate uridyltransferase) bound to three magnesium ions and ATP at the active site. Acta Crystallogr F Struct Biol Commun 2014; 70:703-8. [PMID: 24915076 PMCID: PMC4051520 DOI: 10.1107/s2053230x14008279] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 04/12/2014] [Indexed: 11/10/2022] Open
Abstract
N-Acetylglucosamine-1-phosphate uridyltransferase (GlmU), a bifunctional enzyme exclusive to prokaryotes, belongs to the family of sugar nucleotidyltransferases (SNTs). The enzyme binds GlcNAc-1-P and UTP, and catalyzes a uridyltransfer reaction to synthesize UDP-GlcNAc, an important precursor for cell-wall biosynthesis. As many SNTs are known to utilize a broad range of substrates, substrate specificity in GlmU was probed using biochemical and structural studies. The enzymatic assays reported here demonstrate that GlmU is specific for its natural substrates UTP and GlcNAc-1-P. The crystal structure of GlmU bound to ATP and GlcNAc-1-P provides molecular details for the inability of the enzyme to utilize ATP for the nucleotidyltransfer reaction. ATP binding results in an inactive pre-catalytic enzyme-substrate complex, where it adopts an unusual conformation such that the reaction cannot be catalyzed; here, ATP is shown to be bound together with three Mg2+ ions. Overall, this structure represents the binding of an inhibitory molecule at the active site and can potentially be used to develop new inhibitors of the enzyme. Further, similar to DNA/RNA polymerases, GlmU was recently recognized to utilize two metal ions, MgA2+ and MgB2+, to catalyze the uridyltransfer reaction. Interestingly, displacement of MgB2+ from its usual catalytically competent position, as noted in the crystal structure of RNA polymerase in an inactive state, was considered to be a key factor inhibiting the reaction. Surprisingly, in the current structure of GlmU MgB2+ is similarly displaced; this raises the possibility that an analogous inhibitory mechanism may be operative in GlmU.
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Affiliation(s)
- Neha Vithani
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208 016, India
| | - Vaibhav Bais
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208 016, India
| | - Balaji Prakash
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208 016, India
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22
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Jagtap PKA, Verma SK, Vithani N, Bais VS, Prakash B. Crystal structures identify an atypical two-metal-ion mechanism for uridyltransfer in GlmU: its significance to sugar nucleotidyl transferases. J Mol Biol 2013; 425:1745-59. [PMID: 23485416 DOI: 10.1016/j.jmb.2013.02.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 02/08/2013] [Accepted: 02/14/2013] [Indexed: 11/17/2022]
Abstract
N-Acetylglucosamine-1-phosphate uridyltransferase (GlmU), exclusive to prokaryotes, is a bifunctional enzyme that synthesizes UDP-GlcNAc-an important component of the cell wall of many microorganisms. Uridyltransfer, one of the reactions it catalyzes, involves binding GlcNAc-1-P, UTP and Mg(2+) ions; however, whether one or two ions catalyze this reaction remains ambiguous. Here, we resolve this using biochemical and crystallographic studies on GlmU from Mycobacterium tuberculosis (GlmU(Mtb)) and identify a two-metal-ion mechanism (mechanism-B). In contrast to well-established two-metal mechanism (mechanism-A) for enzymes acting on nucleic acids, mechanism-B is distinct in the way the two Mg(2+) ions (Mg(2+)A and Mg(2+)B) are positioned and stabilized. Further, attempts to delineate the roles of the metal ions in substrate stabilization, nucleophile activation and transition-state stabilization are presented. Interestingly, a detailed analysis of the available structures of sugar nucleotidyl transferases (SNTs) suggests that they too would utilize mechanism-B rather than mechanism-A. Based on this, SNTs could be classified into Group-I, which employs the two-metal mechanism-B as in GlmU, and Group-II that employs a variant one-metal mechanism-B, wherein the role of Mg(2+)A is substituted by a conserved lysine. Strikingly, eukaryotic SNTs appear confined to Group-II. Recognizing these differences may be important in the design of selective inhibitors against microbial nucleotidyl transferases.
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Affiliation(s)
- Pravin Kumar Ankush Jagtap
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
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