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Kumar M, Tripathi MK, Gupta D, Kumar S, Biswas NR, Ethayathulla AS, Kaur P. N-acetylglucosamine-phosphatidylinositol de-N-acetylase as a novel target for probing potential inhibitor against Leishmania donovani. J Biomol Struct Dyn 2023; 41:1904-1918. [PMID: 35014594 DOI: 10.1080/07391102.2021.2025429] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Leishmania donavani is the causative agent of leishmaniasis, responsible for social and economic disruption, especially in developing countries. Lack of effective drugs with few side effects have necessitated the discovery of newer therapeutic solutions for leishmaniasis. Glycophosphatidylinositol (GPI) synthesis plays a vital role in protozoan cell membranes structural formation and antigenic modification. Hence, any disruption in its biosynthesis can prove fatal to the parasitic protozoans. N-acetylglucosamine-phosphatidylinositol de-N-acetylase (NAGP-deacetylase) is an enzyme from the GPI biosynthetic pathway that catalyzes the deacetylation of N-acetylglucosaminylphosphatidylinositol to glucosaminylphosphatidylinositol, a step essential for the proper functioning of the enzyme. In the quest for novel scaffolds as anti-leishmaniasis agents, we have executed in silico virtual screening, density function theory, molecular dynamics and MM-GBSA based energy calculations with a natural product library and a diverse library set from Chembridge database. Two compounds, 14671 and 4610, were identified at the enzyme's active site and interacted with catalytic residues, Asp43, Asp44, His41, His147, His 150, Arg80 and Arg231. Both molecules exhibited stable conformation in their protein-ligand complexes with binding free energies for compound-14671 and compound-4610 of -54 ± 4 and -50 ± 4 kcal/mol, respectively. These scaffolds can be incorporated in future synthetic determinations, focusing on developing druggable inhibitor support, increasing potency, and introducing species selectivity.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Mukesh Kumar
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | | | - Deepali Gupta
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Sanjit Kumar
- Centre for Bioseparation Technology (CBST), Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | - Nihar Ranjan Biswas
- Department of Pharmacology, Indira Gandhi Institute of Medical Science (IGIMS), Patna, India
| | - A S Ethayathulla
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Punit Kaur
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
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2
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Pascual S, Planas A. Carbohydrate de-N-acetylases acting on structural polysaccharides and glycoconjugates. Curr Opin Chem Biol 2020; 61:9-18. [PMID: 33075728 DOI: 10.1016/j.cbpa.2020.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/06/2020] [Accepted: 09/08/2020] [Indexed: 12/14/2022]
Abstract
Deacetylation of N-acetylhexosamine residues in structural polysaccharides and glycoconjugates is catalyzed by different families of carbohydrate esterases that, despite different structural folds, share a common metal-assisted acid/base mechanism with the metal cation coordinated with a conserved Asp-His-His triad. These enzymes serve diverse biological functions in the modification of cell-surface polysaccharides in bacteria and fungi as well as in the metabolism of hexosamines in the biosynthesis of cellular glycoconjugates. Focusing on carbohydrate de-N-acetylases, this article summarizes the background of the different families from a structural and functional viewpoint and covers advances in the characterization of novel enzymes over the last 2-3 years. Current research is addressed to the identification of new deacetylases and unravel their biological functions as they are candidate targets for the design of antimicrobials against pathogenic bacteria and fungi. Likewise, some families are also used as biocatalysts for the production of defined glycostructures with diverse applications.
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Affiliation(s)
- Sergi Pascual
- Laboratory of Biochemistry, Institut Químic de Sarrià, University Ramon Llull, 08017, Barcelona, Spain
| | - Antoni Planas
- Laboratory of Biochemistry, Institut Químic de Sarrià, University Ramon Llull, 08017, Barcelona, Spain.
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3
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Vobruba S, Kamenik Z, Kadlcik S, Janata J. N-Deacetylation in Lincosamide Biosynthesis Is Catalyzed by a TldD/PmbA Family Protein. ACS Chem Biol 2020; 15:2048-2054. [PMID: 32786288 DOI: 10.1021/acschembio.0c00224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lincosamides are clinically important antibiotics originally produced as microbial specialized metabolites. The complex biosynthesis of lincosamides is coupled to the metabolism of mycothiol as a sulfur donor. Here, we elucidated the N-deacetylation of the mycothiol-derived N-acetyl-l-cysteine residue of a lincosamide intermediate, which is comprised of an amino acid and an aminooctose connected via an amide bond. We purified this intermediate from the culture broth of a deletion mutant strain and tested it as a substrate of recombinant lincosamide biosynthetic proteins in the in vitro assays that were monitored via liquid chromatography-mass spectrometry. Our findings showed that the N-deacetylation reaction is catalyzed by CcbIH/CcbQ or LmbIH/LmbQ proteins in celesticetin and lincomycin biosynthesis, respectively. These are the first N-deacetylases from the TldD/PmbA protein family, from which otherwise only several proteases and peptidases were functionally characterized. Furthermore, we present a sequence similarity network of TldD/PmbA proteins, which suggests that the lincosamide N-deacetylases are unique among these widely distributed proteins.
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Affiliation(s)
- Simon Vobruba
- Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Zdenek Kamenik
- Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Stanislav Kadlcik
- Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Janata
- Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
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4
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Guo Y, Gong W, Wang L, Guo J, Jin G, Gu G, Guo Z. Characterization and biochemical investigation of the potential inositol monophosphate phosphatase involved in bacterial mycothiol biosynthesis. J Carbohydr Chem 2019. [DOI: 10.1080/07328303.2018.1559326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Yuchuan Guo
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, China
- Department of Chemistry, University of Florida, Gainesville, USA
| | - Wei Gong
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, China
| | - Lizhen Wang
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, China
| | - Jiatong Guo
- Department of Chemistry, University of Florida, Gainesville, USA
| | - Guoxia Jin
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan, China
| | - Guofeng Gu
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, China
| | - Zhongwu Guo
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, China
- Department of Chemistry, University of Florida, Gainesville, USA
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Bürger M, Chory J. Structural and chemical biology of deacetylases for carbohydrates, proteins, small molecules and histones. Commun Biol 2018; 1:217. [PMID: 30534609 PMCID: PMC6281622 DOI: 10.1038/s42003-018-0214-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 10/31/2018] [Indexed: 01/02/2023] Open
Abstract
Deacetylation is the removal of an acetyl group and occurs on a plethora of targets and for a wide range of biological reasons. Several pathogens deacetylate their surface carbohydrates to evade immune response or to support biofilm formation. Furthermore, dynamic acetylation/deacetylation cycles govern processes from chromatin remodeling to posttranslational modifications that compete with phosphorylation. Acetylation usually occurs on nitrogen and oxygen atoms and are referred to as N- and O-acetylation, respectively. This review discusses the structural prerequisites that enzymes must have to catalyze the deacetylation reaction, and how they adapted by formation of specific substrate and metal binding sites. Marco Bürger and Joanne Chory discuss the structural requirements for enzymes carrying out deacetylation reactions for various functions across phyla. They explore how these enzymes have adapted to and achieved specificity on a large number of target molecules.
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Affiliation(s)
- Marco Bürger
- 1Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037 USA
| | - Joanne Chory
- 1Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037 USA.,2Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037 USA
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7
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Guo Y, Wang L, Guo J, Gu G, Guo Z. Biochemical studies of inositol N-acetylglucosaminyltransferase involved in mycothiol biosynthesis in Corynebacterium diphtheria. Org Biomol Chem 2017; 15:3775-3782. [DOI: 10.1039/c7ob00555e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
First-time expression, isolation, biochemical characterization, and mutagenesis studies of a MshA from Corynebacterium diphtheria involved in its mycothiol biosynthesis.
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Affiliation(s)
- Yuchuan Guo
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology
- Shandong University
- Jinan 250100
- China
- Department of Chemistry
| | - Lizhen Wang
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology
- Shandong University
- Jinan 250100
- China
| | - Jiatong Guo
- Department of Chemistry
- University of Florida
- Gainesville
- USA
| | - Guofeng Gu
- National Glycoengineering Research Center and Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology
- Shandong University
- Jinan 250100
- China
| | - Zhongwu Guo
- Department of Chemistry
- University of Florida
- Gainesville
- USA
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Nakamura T, Yonezawa Y, Tsuchiya Y, Niiyama M, Ida K, Oshima M, Morita J, Uegaki K. Substrate recognition of N,N′-diacetylchitobiose deacetylase from Pyrococcus horikoshii. J Struct Biol 2016; 195:286-293. [DOI: 10.1016/j.jsb.2016.07.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/20/2016] [Accepted: 07/22/2016] [Indexed: 10/21/2022]
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Huang X, Hernick M. Automated docking studies provide insights into molecular determinants of ligand recognition by N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside deacetylase (MshB). Biopolymers 2016; 101:406-17. [PMID: 24037975 DOI: 10.1002/bip.22397] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 08/19/2013] [Accepted: 08/20/2013] [Indexed: 11/10/2022]
Abstract
The metal-dependent deacetylase N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside deacetylase (MshB) catalyzes the deacetylation of N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside (GlcNAc-Ins), the committed step in mycothiol (MSH) biosynthesis. MSH is the thiol redox buffer used by mycobacteria to protect against oxidative damage and is involved in the detoxification of xenobiotics. As such, MshB is a target for the discovery of new drugs to treat tuberculosis (TB). While MshB substrate specificity and inhibitor activity have been probed extensively using enzyme kinetics, information regarding the molecular basis for the observed differences in substrate specificity and inhibitor activity is lacking. Herein we begin to examine the molecular determinants of MshB substrate specificity using automated docking studies with a set of known MshB substrates. Results from these studies offer insights into molecular recognition by MshB via identification of side chains and dynamic loops that may play roles in ligand binding. Additionally, results from these studies suggest that a hydrophobic cavity adjacent to the active site may be one important determinant of MshB substrate specificity. Importantly, this hydrophobic cavity may be advantageous for the design of MshB inhibitors with high affinity and specificity as potential TB drugs.
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Affiliation(s)
- Xinyi Huang
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061
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Mazurkewich S, Brott AS, Kimber MS, Seah SYK. Structural and Kinetic Characterization of the 4-Carboxy-2-hydroxymuconate Hydratase from the Gallate and Protocatechuate 4,5-Cleavage Pathways of Pseudomonas putida KT2440. J Biol Chem 2016; 291:7669-86. [PMID: 26867578 PMCID: PMC4817193 DOI: 10.1074/jbc.m115.682054] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 02/03/2016] [Indexed: 11/06/2022] Open
Abstract
The bacterial catabolism of lignin and its breakdown products is of interest for applications in industrial processing of ligno-biomass. The gallate degradation pathway ofPseudomonas putidaKT2440 requires a 4-carboxy-2-hydroxymuconate (CHM) hydratase (GalB), which has a 12% sequence identity to a previously identified CHM hydratase (LigJ) fromSphingomonassp. SYK-6. The structure of GalB was determined and found to be a member of the PIG-LN-acetylglucosamine deacetylase family; GalB is structurally distinct from the amidohydrolase fold of LigJ. LigJ has the same stereospecificity as GalB, providing an example of convergent evolution for catalytic conversion of a common metabolite in bacterial aromatic degradation pathways. Purified GalB contains a bound Zn(2+)cofactor; however the enzyme is capable of using Fe(2+)and Co(2+)with similar efficiency. The general base aspartate in the PIG-L deacetylases is an alanine in GalB; replacement of the alanine with aspartate decreased the GalB catalytic efficiency for CHM by 9.5 × 10(4)-fold, and the variant enzyme did not have any detectable hydrolase activity. Kinetic analyses and pH dependence studies of the wild type and variant enzymes suggested roles for Glu-48 and His-164 in the catalytic mechanism. A comparison with the PIG-L deacetylases led to a proposed mechanism for GalB wherein Glu-48 positions and activates the metal-ligated water for the hydration reaction and His-164 acts as a catalytic acid.
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Affiliation(s)
- Scott Mazurkewich
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Ashley S Brott
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Matthew S Kimber
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Stephen Y K Seah
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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11
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Tan S, Russell DG. Trans-species communication in the Mycobacterium tuberculosis-infected macrophage. Immunol Rev 2015; 264:233-48. [PMID: 25703563 DOI: 10.1111/imr.12254] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Much of the infection cycle of Mycobacterium tuberculosis (Mtb) is spent within its host cell, the macrophage. As a consequence of the chronic, enduring nature of the infection, this cell-cell interaction has become highly intimate, and the bacterium has evolved to detect, react to, and manipulate the evolving, immune-modulated phenotype of its host. In this review, we discuss the nature of the endosomal/lysosomal continuum, the characterization of the bacterium's transcriptional responses during the infection cycle, and the dominant environmental cues that shape this response. We also discuss how the metabolism of both cells is modulated by the infection and the impact that this has on the progression of the granuloma. Finally, we detail how these transcriptional responses can be exploited to construct reporter bacterial strains to probe the temporal and spatial environmental shifts experienced by Mtb during the course of experimental infections. These reporter strains provide new insights into the fitness of Mtb under immune- and drug-mediated pressure.
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Affiliation(s)
- Shumin Tan
- Department of Microbiology and Immunology, Cornell University, College of Veterinary Medicine, Ithaca, NY, USA
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12
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Romero JM, Martin M, Ramirez CL, Dumas VG, Marti MA. Efficient Calculation of Enzyme Reaction Free Energy Profiles Using a Hybrid Differential Relaxation Algorithm: Application to Mycobacterial Zinc Hydrolases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 100:33-65. [PMID: 26415840 DOI: 10.1016/bs.apcsb.2015.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Determination of the free energy profile for an enzyme reaction mechanism is of primordial relevance, paving the way for our understanding of the enzyme's catalytic power at the molecular level. Although hybrid, mostly DFT-based, QM/MM methods have been extensively applied to this type of studies, achieving accurate and statistically converged results at a moderate computational cost is still an open challenge. Recently, we have shown that accurate results can be achieved in less computational time, combining Jarzynski's relationship with a hybrid differential relaxation algorithm (HyDRA), which allows partial relaxation of the solvent during the nonequilibrium steering of the reaction. In this work, we have applied this strategy to study two mycobacterial zinc hydrolases. Mycobacterium tuberculosis infections are still a worldwide problem and thus characterization and validation of new drug targets is an intense field of research. Among possible drug targets, recently two essential zinc hydrolases, MshB (Rv1170) and MA-amidase (Rv3717), have been proposed and structurally characterized. Although possible mechanisms have been proposed by analogy to the widely studied human Zn hydrolases, several key issues, particularly those related to Zn coordination sphere and its role in catalysis, remained unanswered. Our results show that mycobacterial Zn hydrolases share a basic two-step mechanism. First, the attacking water becomes deprotonated by the conserved base and establishes the new C-O bond leading to a tetrahedral intermediate. The intermediate requires moderate reorganization to allow for proton transfer to the amide N and C-N bond breaking to occur in the second step. Zn ion plays a key role in stabilizing the tetrahedral intermediate and balancing the negative charge of the substrate during hydroxide ion attack. Finally, comparative analysis of other Zn hydrolases points to a convergent mechanistic evolution.
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Affiliation(s)
- Juan Manuel Romero
- Instituto de Química Física de los Materiales Medio Ambiente y Energía (INQUIMAE), UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Mariano Martin
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Claudia Lilián Ramirez
- Instituto de Química Física de los Materiales Medio Ambiente y Energía (INQUIMAE), UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Victoria Gisel Dumas
- Instituto de Química Física de los Materiales Medio Ambiente y Energía (INQUIMAE), UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina; Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Marcelo Adrián Marti
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina; Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN) CONICET, Ciudad Universitaria, Buenos Aires, Argentina.
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13
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Huang X, Hernick M. Molecular Determinants of N-Acetylglucosamine Recognition and Turnover by N-Acetyl-1-d-myo-inosityl-2-amino-2-deoxy-α-d-glucopyranoside Deacetylase (MshB). Biochemistry 2015; 54:3784-90. [DOI: 10.1021/acs.biochem.5b00068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xinyi Huang
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Marcy Hernick
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Pharmaceutical Sciences, Appalachian College of Pharmacy, Oakwood, Virginia 24631, United States
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14
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Identity of cofactor bound to mycothiol conjugate amidase (Mca) influenced by expression and purification conditions. Biometals 2015; 28:755-63. [DOI: 10.1007/s10534-015-9864-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/24/2015] [Indexed: 10/23/2022]
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15
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Si M, Long M, Chaudhry MT, Xu Y, Zhang P, Zhang L, Shen X. Functional characterization of Corynebacterium glutamicum mycothiol S-conjugate amidase. PLoS One 2014; 9:e115075. [PMID: 25514023 PMCID: PMC4267739 DOI: 10.1371/journal.pone.0115075] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 11/18/2014] [Indexed: 11/18/2022] Open
Abstract
The present study focuses on the genetic and biochemical characterization of mycothiol S-conjugate amidase (Mca) of Corynebacterium glutamicum. Recombinant C. glutamicum Mca was heterologously expressed in Escherichia coli and purified to apparent homogeneity. The molecular weight of native Mca protein determined by gel filtration chromatography was 35 kDa, indicating that Mca exists as monomers in the purification condition. Mca showed amidase activity with mycothiol S-conjugate of monobromobimane (MSmB) in vivo while mca mutant lost the ability to cleave MSmB. In addition, Mca showed limited deacetylase activity with N-acetyl-D-glucosamine (GlcNAc) as substrate. Optimum pH for amidase activity was between 7.5 and 8.5, while the highest activity in the presence of Zn2+ confirmed Mca as a zinc metalloprotein. Amino acid residues conserved among Mca family members were located in C. glutamicum Mca and site-directed mutagenesis of these residues indicated that Asp14, Tyr137, His139 and Asp141 were important for activity. The mca deletion mutant showed decreased resistance to antibiotics, alkylating agents, oxidants and heavy metals, and these sensitive phenotypes were recovered in the complementary strain to a great extent. The physiological roles of Mca in resistance to various toxins were further supported by the induced expression of Mca in C. glutamicum under various stress conditions, directly under the control of the stress-responsive extracytoplasmic function-sigma (ECF-σ) factor SigH.
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Affiliation(s)
- Meiru Si
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Mingxiu Long
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Muhammad Tausif Chaudhry
- Environmental Analytical Laboratory, National Physical & Standards Laboratory, PCSIR, Islamabad, Pakistan
| | - Yixiang Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Pan Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Lei Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
- * E-mail:
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Viars S, Valentine J, Hernick M. Structure and function of the LmbE-like superfamily. Biomolecules 2014; 4:527-45. [PMID: 24970229 PMCID: PMC4101496 DOI: 10.3390/biom4020527] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/18/2014] [Accepted: 04/18/2014] [Indexed: 11/17/2022] Open
Abstract
The LmbE-like superfamily is comprised of a series of enzymes that use a single catalytic metal ion to catalyze the hydrolysis of various substrates. These substrates are often key metabolites for eukaryotes and prokaryotes, which makes the LmbE-like enzymes important targets for drug development. Herein we review the structure and function of the LmbE-like proteins identified to date. While this is the newest superfamily of metallohydrolases, a growing number of functionally interesting proteins from this superfamily have been characterized. Available crystal structures of LmbE-like proteins reveal a Rossmann fold similar to lactate dehydrogenase, which represented a novel fold for (zinc) metallohydrolases at the time the initial structure was solved. The structural diversity of the N-acetylglucosamine containing substrates affords functional diversity for the LmbE-like enzyme superfamily. The majority of enzymes identified to date are metal-dependent deacetylases that catalyze the hydrolysis of a N-acetylglucosamine moiety on substrate using a combination of amino acid side chains and a single bound metal ion, predominantly zinc. The catalytic zinc is coordinated to proteins via His2-Asp-solvent binding site. Additionally, studies indicate that protein dynamics play important roles in regulating access to the active site and facilitating catalysis for at least two members of this protein superfamily.
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Affiliation(s)
- Shane Viars
- Department of Pharmaceutical Sciences, Appalachian College of Pharmacy, Oakwood, VA 24631, USA.
| | - Jason Valentine
- Department of Pharmaceutical Sciences, Appalachian College of Pharmacy, Oakwood, VA 24631, USA.
| | - Marcy Hernick
- Department of Pharmaceutical Sciences, Appalachian College of Pharmacy, Oakwood, VA 24631, USA.
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Mine S, Niiyama M, Hashimoto W, Ikegami T, Koma D, Ohmoto T, Fukuda Y, Inoue T, Abe Y, Ueda T, Morita J, Uegaki K, Nakamura T. Expression from engineeredEscherichia colichromosome and crystallographic study of archaealN,N′-diacetylchitobiose deacetylase. FEBS J 2014; 281:2584-96. [DOI: 10.1111/febs.12805] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 03/31/2014] [Accepted: 04/03/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Shouhei Mine
- National Institute of Advanced Industrial Science and Technology; Osaka Japan
| | - Mayumi Niiyama
- National Institute of Advanced Industrial Science and Technology; Osaka Japan
| | - Wakana Hashimoto
- National Institute of Advanced Industrial Science and Technology; Osaka Japan
- Faculty of Human Life and Science; Doshisha Women's College of Liberal Arts; Kyoto Japan
| | | | - Daisuke Koma
- Osaka Municipal Technical Research Institute; Japan
| | | | - Yohta Fukuda
- Graduate School of Engineering; Osaka University; Japan
| | | | - Yoshito Abe
- Graduate School of Pharmaceutical Sciences; Kyushu University; Fukuoka Japan
| | - Tadashi Ueda
- Graduate School of Pharmaceutical Sciences; Kyushu University; Fukuoka Japan
| | - Junji Morita
- Faculty of Human Life and Science; Doshisha Women's College of Liberal Arts; Kyoto Japan
| | - Koichi Uegaki
- National Institute of Advanced Industrial Science and Technology; Osaka Japan
| | - Tsutomu Nakamura
- National Institute of Advanced Industrial Science and Technology; Osaka Japan
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18
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Hernick M. Mycothiol: a target for potentiation of rifampin and other antibiotics againstMycobacterium tuberculosis. Expert Rev Anti Infect Ther 2014; 11:49-67. [DOI: 10.1586/eri.12.152] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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19
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Nilewar SS, Kathiravan MK. Mycothiol: a promising antitubercular target. Bioorg Chem 2013; 52:62-8. [PMID: 24368170 DOI: 10.1016/j.bioorg.2013.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 11/12/2013] [Accepted: 11/15/2013] [Indexed: 11/30/2022]
Abstract
Tuberculosis (TB) is the world's second commonest cause of death next to HIV/AIDS. The increasing emergence of multi drug resistance and the recalcitrant nature of persistent infections pose an additional challenge for the treatment of TB. Due to the development of resistance to conventional antibiotics there is a need for new therapeutic strategies to combat M. tuberculosis. One such target is Mycothiol (MSH), a major low molecular-mass thiol in mycobacteria, an important cellular anti-oxidant. MSH is present only in actinomycetes and hence is a good target. This review explores mycothiol as a potential target against tuberculosis and various research ongoing worldwide.
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Affiliation(s)
- S S Nilewar
- Sinhgad College of Pharmacy, Vadgoan (BK), Pune 411041, India
| | - M K Kathiravan
- Sinhgad College of Pharmacy, Vadgoan (BK), Pune 411041, India.
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20
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Cross-functionalities of Bacillus deacetylases involved in bacillithiol biosynthesis and bacillithiol-S-conjugate detoxification pathways. Biochem J 2013; 454:239-47. [PMID: 23758290 DOI: 10.1042/bj20130415] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BshB, a key enzyme in bacillithiol biosynthesis, hydrolyses the acetyl group from N-acetylglucosamine malate to generate glucosamine malate. In Bacillus anthracis, BA1557 has been identified as the N-acetylglucosamine malate deacetylase (BshB); however, a high content of bacillithiol (~70%) was still observed in the B. anthracis ∆BA1557 strain. Genomic analysis led to the proposal that another deacetylase could exhibit cross-functionality in bacillithiol biosynthesis. In the present study, BA1557, its paralogue BA3888 and orthologous Bacillus cereus enzymes BC1534 and BC3461 have been characterized for their deacetylase activity towards N-acetylglucosamine malate, thus providing biochemical evidence for this proposal. In addition, the involvement of deacetylase enzymes is also expected in bacillithiol-detoxifying pathways through formation of S-mercapturic adducts. The kinetic analysis of bacillithiol-S-bimane conjugate favours the involvement of BA3888 as the B. anthracis bacillithiol-S-conjugate amidase (Bca). The high degree of specificity of this group of enzymes for its physiological substrate, along with their similar pH-activity profile and Zn²⁺-dependent catalytic acid-base reaction provides further evidence for their cross-functionalities.
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21
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Paritala H, Carroll KS. New targets and inhibitors of mycobacterial sulfur metabolism. Infect Disord Drug Targets 2013; 13:85-115. [PMID: 23808874 PMCID: PMC4332622 DOI: 10.2174/18715265113139990022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/08/2013] [Indexed: 11/22/2022]
Abstract
The identification of new antibacterial targets is urgently needed to address multidrug resistant and latent tuberculosis infection. Sulfur metabolic pathways are essential for survival and the expression of virulence in many pathogenic bacteria, including Mycobacterium tuberculosis. In addition, microbial sulfur metabolic pathways are largely absent in humans and therefore, represent unique targets for therapeutic intervention. In this review, we summarize our current understanding of the enzymes associated with the production of sulfated and reduced sulfur-containing metabolites in Mycobacteria. Small molecule inhibitors of these catalysts represent valuable chemical tools that can be used to investigate the role of sulfur metabolism throughout the Mycobacterial lifecycle and may also represent new leads for drug development. In this light, we also summarize recent progress made in the development of inhibitors of sulfur metabolism enzymes.
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Affiliation(s)
| | - Kate S. Carroll
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida, 33458, USA
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22
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Rogers IL, Gammon DW, Naidoo KJ. Conformational preferences of plumbagin with phenyl-1-thioglucoside conjugates in solution and bound to MshB determined by aromatic association. Carbohydr Res 2013; 371:52-60. [DOI: 10.1016/j.carres.2013.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 02/10/2013] [Accepted: 02/12/2013] [Indexed: 10/27/2022]
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23
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Fahey RC. Glutathione analogs in prokaryotes. Biochim Biophys Acta Gen Subj 2012; 1830:3182-98. [PMID: 23075826 DOI: 10.1016/j.bbagen.2012.10.006] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/25/2012] [Accepted: 10/08/2012] [Indexed: 01/17/2023]
Abstract
BACKGROUND Oxygen is both essential and toxic to all forms of aerobic life and the chemical versatility and reactivity of thiols play a key role in both aspects. Cysteine thiol groups have key catalytic functions in enzymes but are readily damaged by reactive oxygen species (ROS). Low-molecular-weight thiols provide protective buffers against the hazards of ROS toxicity. Glutathione is the small protective thiol in nearly all eukaryotes but in prokaryotes the situation is far more complex. SCOPE OF REVIEW This review provides an introduction to the diversity of low-molecular-weight thiol protective systems in bacteria. The topics covered include the limitations of cysteine as a protector, the multiple origins and distribution of glutathione biosynthesis, mycothiol biosynthesis and function in Actinobacteria, recent discoveries involving bacillithiol found in Firmicutes, new insights on the biosynthesis and distribution of ergothioneine, and the potential protective roles played by coenzyme A and other thiols. MAJOR CONCLUSIONS Bacteria have evolved a diverse collection of low-molecular-weight protective thiols to deal with oxygen toxicity and environmental challenges. Our understanding of how many of these thiols are produced and utilized is still at an early stage. GENERAL SIGNIFICANCE Extensive diversity existed among prokaryotes prior to evolution of the cyanobacteria and the development of an oxidizing atmosphere. Bacteria that managed to adapt to life under oxygen evolved, or acquired, the ability to produce a variety of small thiols for protection against the hazards of aerobic metabolism. Many pathogenic prokaryotes depend upon novel thiol protection systems that may provide targets for new antibacterial agents. This article is part of a Special Issue entitled Cellular functions of glutathione.
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Affiliation(s)
- Robert C Fahey
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
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Broadley SG, Gumbart JC, Weber BW, Marakalala MJ, Steenkamp DJ, Sewell BT. A new crystal form of MshB from Mycobacterium tuberculosis with glycerol and acetate in the active site suggests the catalytic mechanism. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:1450-9. [PMID: 23090394 DOI: 10.1107/s090744491203449x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 08/02/2012] [Indexed: 11/10/2022]
Abstract
MshB, a zinc-based deacetylase, catalyses a step in the mycothiol biosynthetic pathway that involves the deacetylation of 1-O-(2-acetamido-2-deoxy-α-D-glucopyranosyl)-D-myo-inositol (GlcNAc-Ins), via cleavage of an amide bond, to 1-O-(2-amino-2-deoxy-α-D-glucopyranosyl)-D-myo-inositol (GlcN-Ins) and acetate. In this study, MshB was expressed, purified and crystallized. A new crystal form was encountered in 0.1 M sodium acetate, 0.2 M ammonium sulfate, 25% PEG 4000 pH 4.6. The crystals diffracted to 1.95 Å resolution and the resulting electron-density map revealed glycerol and the reaction product, acetate, in the active site. These ligands enabled the natural substrate GlcNAc-Ins to be modelled in the active site with some certainty. One acetate O atom is hydrogen bonded to Tyr142 and is located 2.5 Å from the catalytic zinc. The other acetate O atom is located 2.7 Å from a carboxylate O atom of Asp15. This configuration strongly suggests that Asp15 acts both as a general base catalyst in the nucleophilic attack of water on the amide carbonyl C atom and in its protonated form acts as a general acid to protonate the amide N atom. The configuration of Tyr142 differs from that observed previously in crystal structures of MshB (PDB entries 1q74 and 1q7t) and its location provides direct structural support for recently published biochemical and mutational studies suggesting that this residue is involved in a conformational change on substrate binding and contributes to the oxyanion hole that stabilizes the tetrahedral intermediate.
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Affiliation(s)
- Simon Gareth Broadley
- Department of Molecular and Cell Biology, University of Cape Town, University Avenue, Rondebosch, Western Cape 7700, South Africa
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25
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Lamprecht DA, Muneri NO, Eastwood H, Naidoo KJ, Strauss E, Jardine A. An enzyme-initiated Smiles rearrangement enables the development of an assay of MshB, the GlcNAc-Ins deacetylase of mycothiol biosynthesis. Org Biomol Chem 2012; 10:5278-88. [PMID: 22678300 DOI: 10.1039/c2ob25429h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
MshB is the N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-D-glucopyranoside (GlcNAc-Ins) deacetylase active as one of the enzymes involved in the biosynthesis of mycothiol (MSH), a protective low molecular weight thiol present only in Mycobacterium tuberculosis and other actinomycetes. In this study, structural analogues of GlcNAc-Ins in which the inosityl moiety is replaced by a chromophore were synthesized and evaluated as alternate substrates of MshB, with the goal of identifying a compound that would be useful in high-throughput assays of the enzyme. In an unexpected and surprising finding one of the GlcNAc-Ins analogues is shown to undergo a Smiles rearrangement upon MshB-mediated deacetylation, uncovering a free thiol group. We demonstrate that this chemistry can be exploited for the development of the first continuous assay of MshB activity based on the detection of thiol formation by DTNB (Ellman's reagent); such an assay should be ideally suited for the identification of MshB inhibitors by means of high-throughput screens in microplates.
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Affiliation(s)
- Dirk A Lamprecht
- Department of Biochemistry, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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26
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Huang X, Hernick M. Examination of mechanism of N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside deacetylase (MshB) reveals unexpected role for dynamic tyrosine. J Biol Chem 2012; 287:10424-10434. [PMID: 22315231 DOI: 10.1074/jbc.m111.320184] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Actinomycetes are a group of gram-positive bacteria that includes pathogenic mycobacterial species, such as Mycobacterium tuberculosis. These organisms do not have glutathione and instead utilize the small molecule mycothiol (MSH) as their primary reducing agent and for the detoxification of xenobiotics. Due to these important functions, enzymes involved in MSH biosynthesis and MSH-dependent detoxification are targets for drug development. The metal-dependent deacetylase N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside deacetylase (MshB) catalyzes the hydrolysis of N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside to form 1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside and acetate in MSH biosynthesis. Herein we examine the chemical mechanism of MshB. We demonstrate that the side chains of Asp-15, Tyr-142, His-144, and Asp-146 are important for catalytic activity. We show that NaF is an uncompetitive inhibitor of MshB, consistent with a metal-water/hydroxide functioning as the reactive nucleophile in the catalytic mechanism. We have previously shown that MshB activity has a bell-shaped dependence on pH with pK(a) values of ∼7.3 and 10.5 (Huang, X., Kocabas, E. and Hernick, M. (2011) J. Biol. Chem. 286, 20275-20282). Mutagenesis experiments indicate that the observed pK(a) values reflect ionization of Asp-15 and Tyr-142, respectively. Together, findings from our studies suggest that MshB functions through a general acid-base pair mechanism with the side chain of Asp-15 functioning as the general base catalyst and His-144 serving as the general acid catalyst, whereas the side chain of Tyr-142 probably assists in polarizing substrate/stabilizing the oxyanion intermediate. Additionally, our results indicate that Tyr-142 is a dynamic side chain that plays key roles in catalysis, modulating substrate binding, chemistry, and product release.
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Affiliation(s)
- Xinyi Huang
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061
| | - Marcy Hernick
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061.
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27
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Huang X, Kocabas E, Hernick M. The activity and cofactor preferences of N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-alpha-D-glucopyranoside deacetylase (MshB) change depending on environmental conditions. J Biol Chem 2011; 286:20275-82. [PMID: 21507949 DOI: 10.1074/jbc.m111.234229] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Actinomycetes, such as Mycobacterium species, are Gram-positive bacteria that utilize the small molecule mycothiol (MSH) as their primary reducing agent. Consequently, the enzymes involved in MSH biosynthesis are targets for drug development. The metal-dependent enzyme N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside deacetylase (MshB) catalyzes the hydrolysis of N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside to form 1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside and acetate, the fourth overall step in MSH biosynthesis. Inhibitors of metalloenzymes typically contain a group that binds to the active site metal ion; thus, a comprehensive understanding of the native cofactor(s) of metalloenzymes is critical for the development of biologically effective inhibitors. Herein, we examined the effect of metal ions on the overall activity of MshB and probed the identity of the native cofactor. We found that the activity of MshB follows the trend Fe(2+) > Co(2+) > Zn(2+) > Mn(2+) and Ni(2+). Additionally, our results show that the identity of the cofactor bound to purified MshB is highly dependent on the purification conditions used (aerobic versus anaerobic), as well as the metal ion content of the medium during protein expression. MshB prefers Fe(2+) under anaerobic conditions regardless of the metal ion content of the medium and switches between Fe(2+) and Zn(2+) under aerobic conditions as the metal content of the medium is altered. These results indicate that the cofactor bound to MshB under biological conditions is dependent on environmental conditions, suggesting that MshB may be a cambialistic metallohydrolase that contains a dynamic cofactor. Consequently, biologically effective inhibitors will likely need to dually target Fe(2+)-MshB and Zn(2+)-MshB.
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Affiliation(s)
- Xinyi Huang
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
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28
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Nogales J, Canales A, Jiménez-Barbero J, Serra B, Pingarrón JM, García JL, Díaz E. Unravelling the gallic acid degradation pathway in bacteria: the gal cluster from Pseudomonas putida. Mol Microbiol 2010; 79:359-74. [PMID: 21219457 DOI: 10.1111/j.1365-2958.2010.07448.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is widely distributed in nature, being a major phenolic pollutant and a commonly used antioxidant and building-block for drug development. We have characterized the first complete cluster (gal genes) responsible for growth in GA in a derivative of the model bacterium Pseudomonas putida KT2440. GalT mediates specific GA uptake and chemotaxis, and highlights the critical role of GA transport in bacterial adaptation to GA consumption. The proposed GA degradation via the central intermediate 4-oxalomesaconic acid (OMA) was revisited and all enzymes involved have been identified. Thus, GalD is the prototype of a new subfamily of isomerases that catalyses a biochemical step that remained unknown, i.e. the tautomerization of the OMAketo generated by the GalA dioxygenase to OMAenol. GalB is the founding member of a new family of zinc-containing hydratases that converts OMAenol into 4-carboxy-4-hydroxy-2-oxoadipic acid (CHA). galC encodes the aldolase catalysing CHA cleavage to pyruvic and oxaloacetic acids. The presence of homologous gal clusters outside the Pseudomonas genus sheds light on the evolution and ecology of the gal genes in GA degraders. The gal genes were used for expanding the metabolic abilities of heterologous hosts towards GA degradation, and for engineering a GA cellular biosensor.
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Affiliation(s)
- Juan Nogales
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC. Ramiro de Maeztu 9, 28040 Madrid, Spain
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29
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Parsonage D, Newton GL, Holder RC, Wallace BD, Paige C, Hamilton CJ, Dos Santos PC, Redinbo MR, Reid SD, Claiborne A. Characterization of the N-acetyl-α-D-glucosaminyl l-malate synthase and deacetylase functions for bacillithiol biosynthesis in Bacillus anthracis . Biochemistry 2010; 49:8398-414. [PMID: 20799687 DOI: 10.1021/bi100698n] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Bacillithiol (Cys-GlcN-malate, BSH) has recently been identified as a novel low-molecular weight thiol in Bacillus anthracis, Staphylococcus aureus, and several other Gram-positive bacteria lacking glutathione and mycothiol. We have now characterized the first two enzymes for the BSH biosynthetic pathway in B. anthracis, which combine to produce α-d-glucosaminyl l-malate (GlcN-malate) from UDP-GlcNAc and l-malate. The structure of the GlcNAc-malate intermediate has been determined, as have the kinetic parameters for the BaBshA glycosyltransferase (→GlcNAc-malate) and the BaBshB deacetylase (→GlcN-malate). BSH is one of only two natural products reported to contain a malyl glycoside, and the crystal structure of the BaBshA-UDP-malate ternary complex, determined in this work at 3.3 Å resolution, identifies several active-site interactions important for the specific recognition of l-malate, but not other α-hydroxy acids, as the acceptor substrate. In sharp contrast to the structures reported for the GlcNAc-1-d-myo-inositol-3-phosphate synthase (MshA) apo and ternary complex forms, there is no major conformational change observed in the structures of the corresponding BaBshA forms. A mutant strain of B. anthracis deficient in the BshA glycosyltransferase fails to produce BSH, as predicted. This B. anthracis bshA locus (BA1558) has been identified in a transposon-site hybridization study as required for growth, sporulation, or germination [Day, W. A., Jr., Rasmussen, S. L., Carpenter, B. M., Peterson, S. N., and Friedlander, A. M. (2007) J. Bacteriol. 189, 3296-3301], suggesting that the biosynthesis of BSH could represent a target for the development of novel antimicrobials with broad-spectrum activity against Gram-positive pathogens like B. anthracis. The metabolites that function in thiol redox buffering and homeostasis in Bacillus are not well understood, and we present a composite picture based on this and other recent work.
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Affiliation(s)
- Derek Parsonage
- Center for Structural Biology, Wake Forest University School of Medicine,Winston-Salem, North Carolina 27157, USA
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30
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Deli A, Koutsioulis D, Fadouloglou VE, Spiliotopoulou P, Balomenou S, Arnaouteli S, Tzanodaskalaki M, Mavromatis K, Kokkinidis M, Bouriotis V. LmbE proteins from Bacillus cereus are de-N-acetylases with broad substrate specificity and are highly similar to proteins in Bacillus anthracis. FEBS J 2010; 277:2740-53. [DOI: 10.1111/j.1742-4658.2010.07691.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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Gammon DW, Steenkamp DJ, Mavumengwana V, Marakalala MJ, Mudzunga TT, Hunter R, Munyololo M. Conjugates of plumbagin and phenyl-2-amino-1-thioglucoside inhibit MshB, a deacetylase involved in the biosynthesis of mycothiol. Bioorg Med Chem 2010; 18:2501-14. [DOI: 10.1016/j.bmc.2010.02.049] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2009] [Revised: 02/21/2010] [Accepted: 02/23/2010] [Indexed: 11/26/2022]
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32
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Spencer J, Murphy LM, Conners R, Sessions RB, Gamblin SJ. Crystal Structure of the LasA Virulence Factor from Pseudomonas aeruginosa: Substrate Specificity and Mechanism of M23 Metallopeptidases. J Mol Biol 2010; 396:908-23. [DOI: 10.1016/j.jmb.2009.12.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 12/08/2009] [Accepted: 12/11/2009] [Indexed: 10/20/2022]
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33
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Fan F, Vetting MW, Frantom PA, Blanchard JS. Structures and mechanisms of the mycothiol biosynthetic enzymes. Curr Opin Chem Biol 2009; 13:451-9. [PMID: 19699138 DOI: 10.1016/j.cbpa.2009.07.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 07/13/2009] [Accepted: 07/21/2009] [Indexed: 11/27/2022]
Abstract
In the past decade, the genes encoding all four enzymes responsible for the biosynthesis of mycothiol in Mycobacterium tuberculosis have been identified. Orthologs of each of these have been stably expressed and structurally characterized. The chemical mechanisms of all the four have also been studied. Because of the unique phylogenetic distribution of mycothiol, and the enzymes responsible for its biosynthesis, these enzymes represent interesting potential targets for antimycobacterial agents.
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Affiliation(s)
- Fan Fan
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Biosynthesis and functions of mycothiol, the unique protective thiol of Actinobacteria. Microbiol Mol Biol Rev 2008; 72:471-94. [PMID: 18772286 DOI: 10.1128/mmbr.00008-08] [Citation(s) in RCA: 262] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycothiol (MSH; AcCys-GlcN-Ins) is the major thiol found in Actinobacteria and has many of the functions of glutathione, which is the dominant thiol in other bacteria and eukaryotes but is absent in Actinobacteria. MSH functions as a protected reserve of cysteine and in the detoxification of alkylating agents, reactive oxygen and nitrogen species, and antibiotics. MSH also acts as a thiol buffer which is important in maintaining the highly reducing environment within the cell and protecting against disulfide stress. The pathway of MSH biosynthesis involves production of GlcNAc-Ins-P by MSH glycosyltransferase (MshA), dephosphorylation by the MSH phosphatase MshA2 (not yet identified), deacetylation by MshB to produce GlcN-Ins, linkage to Cys by the MSH ligase MshC, and acetylation by MSH synthase (MshD), yielding MSH. Studies of MSH mutants have shown that the MSH glycosyltransferase MshA and the MSH ligase MshC are required for MSH production, whereas mutants in the MSH deacetylase MshB and the acetyltransferase (MSH synthase) MshD produce some MSH and/or a closely related thiol. Current evidence indicates that MSH biosynthesis is controlled by transcriptional regulation mediated by sigma(B) and sigma(R) in Streptomyces coelicolor. Identified enzymes of MSH metabolism include mycothione reductase (disulfide reductase; Mtr), the S-nitrosomycothiol reductase MscR, the MSH S-conjugate amidase Mca, and an MSH-dependent maleylpyruvate isomerase. Mca cleaves MSH S-conjugates to generate mercapturic acids (AcCySR), excreted from the cell, and GlcN-Ins, used for resynthesis of MSH. The phenotypes of MSH-deficient mutants indicate the occurrence of one or more MSH-dependent S-transferases, peroxidases, and mycoredoxins, which are important targets for future studies. Current evidence suggests that several MSH biosynthetic and metabolic enzymes are potential targets for drugs against tuberculosis. The functions of MSH in antibiotic-producing streptomycetes and in bioremediation are areas for future study.
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Jothivasan VK, Hamilton CJ. Mycothiol: synthesis, biosynthesis and biological functions of the major low molecular weight thiol in actinomycetes. Nat Prod Rep 2008; 25:1091-117. [PMID: 19030604 DOI: 10.1039/b616489g] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Actinomycetes produce mycothiol as their major low molecular weight thiol, which parallels the functions of glutathione found in prokaryotes and most Gram-negative bacteria. This review covers progress that has so far been made in terms of its distribution, biosynthesis and metabolic functions, as well as chemical syntheses of mycothiol and alternative substrates and inhibitors of mycothiol biosynthesis and mycothiol-dependent enzymes. 152 references are cited.
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Zou Y, Brunzelle JS, Nair SK. Crystal structures of lipoglycopeptide antibiotic deacetylases: implications for the biosynthesis of A40926 and teicoplanin. ACTA ACUST UNITED AC 2008; 15:533-45. [PMID: 18559264 DOI: 10.1016/j.chembiol.2008.05.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 05/02/2008] [Accepted: 05/05/2008] [Indexed: 10/21/2022]
Abstract
The lipoglycopeptide antibiotics teicoplanin and A40926 have proven efficacy against Gram-positive pathogens. These drugs are distinguished from glycopeptide antibiotics by N-linked long chain acyl-D-glucosamine decorations that contribute to antibacterial efficacy. During the biosynthesis of lipoglycopeptides, tailoring glycosyltransferases attach an N-acetyl-D-glucosamine to the aglycone, and this N-acetyl-glucosaminyl pseudoaglycone is deacetylated prior to long chain hydrocarbon attachment. Here we present several high-resolution crystal structures of the pseudoaglycone deacetylases from the biosynthetic pathways of teicoplanin and A40926. The cocrystal structure of the teicoplanin pseudoaglycone deacetylase with a fatty acid product provides further insights into the roles of active-site residues, and suggests mechanistic similarities with structurally distinct zinc deacetylases, such as peptidoglycan deacetylase and LpxC. A unique, structurally mobile capping lid, located at the apex of these pseudoaglycone deacetylases, likely serves as a determinant of substrate specificity.
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Affiliation(s)
- Yaozhong Zou
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Vetting MW, Frantom PA, Blanchard JS. Structural and enzymatic analysis of MshA from Corynebacterium glutamicum: substrate-assisted catalysis. J Biol Chem 2008; 283:15834-44. [PMID: 18390549 PMCID: PMC2414306 DOI: 10.1074/jbc.m801017200] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 03/26/2008] [Indexed: 11/06/2022] Open
Abstract
The glycosyltransferase termed MshA catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to 1-L-myo-inositol-1-phosphate in the first committed step of mycothiol biosynthesis. The structure of MshA from Corynebacterium glutamicum was determined both in the absence of substrates and in a complex with UDP and 1-L-myo-inositol-1-phosphate. MshA belongs to the GT-B structural family whose members have a two-domain structure with both domains exhibiting a Rossman-type fold. Binding of the donor sugar to the C-terminal domain produces a 97 degrees rotational reorientation of the N-terminal domain relative to the C-terminal domain, clamping down on UDP and generating the binding site for 1-L-myo-inositol-1-phosphate. The structure highlights the residues important in binding of UDP-N-acetylglucosamine and 1-L-myo-inositol-1-phosphate. Molecular models of the ternary complex suggest a mechanism in which the beta-phosphate of the substrate, UDP-N-acetylglucosamine, promotes the nucleophilic attack of the 3-hydroxyl group of 1-L-myo-inositol-1-phosphate while at the same time promoting the cleavage of the sugar nucleotide bond.
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Affiliation(s)
- Matthew W Vetting
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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Truman AW, Fan Q, Röttgen M, Stegmann E, Leadlay PF, Spencer JB. The Role of Cep15 in the Biosynthesis of Chloroeremomycin: Reactivation of an Ancestral Catalytic Function. ACTA ACUST UNITED AC 2008; 15:476-84. [DOI: 10.1016/j.chembiol.2008.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 03/28/2008] [Accepted: 03/31/2008] [Indexed: 10/22/2022]
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39
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Tomioka H. Development of new antituberculous agents based on new drug targets and structure–activity relationship. Expert Opin Drug Discov 2007; 3:21-49. [DOI: 10.1517/17460441.3.1.21] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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40
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Metaferia BB, Fetterolf BJ, Shazad-ul-Hussan S, Moravec M, Smith JA, Ray S, Gutierrez-Lugo MT, Bewley CA. Synthesis of Natural Product-Inspired Inhibitors of Mycobacterium tuberculosis Mycothiol-Associated Enzymes: The First Inhibitors of GlcNAc-Ins Deacetylase. J Med Chem 2007; 50:6326-36. [DOI: 10.1021/jm070669h] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Belhu B. Metaferia
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Brandon J. Fetterolf
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Syed Shazad-ul-Hussan
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Matthew Moravec
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Jeremy A. Smith
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Satyajit Ray
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Maria-Teresa Gutierrez-Lugo
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Carole A. Bewley
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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41
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Fan F, Luxenburger A, Painter GF, Blanchard JS. Steady-state and pre-steady-state kinetic analysis of Mycobacterium smegmatis cysteine ligase (MshC). Biochemistry 2007; 46:11421-9. [PMID: 17848100 PMCID: PMC2526253 DOI: 10.1021/bi7011492] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mycobacterium tuberculosis and many other members of the Actinomycetes family produce mycothiol, i.e., 1-d-myo-inosityl-2-(N-acetyl-l-cysteinyl)amido-2-deoxy-alpha-d-glucopyranoside (MSH or AcCys-GlcN-Ins), to act against oxidative and antibiotic stress. The biosynthesis of MSH is essential for cell growth and has been proposed to proceed via a biosynthetic pathway involving four key enzymes, MshA-MshD. The MSH biosynthetic enzymes present potential targets for inhibitor design. With this as a long-term goal, we have carried out a kinetic and mechanistic characterization, using steady-state and pre-steady-state approaches, of the recombinant Mycobacterium smegmatis MshC. MshC catalyzes the ATP-dependent condensation of GlcN-Ins and cysteine to form Cys-GlcN-Ins. Initial velocity and inhibition studies show that the steady-state kinetic mechanism of MshC is a Bi Uni Uni Bi Ping Pong mechanism, with ATP binding followed by cysteine binding, release of PPi, binding of GlcN-Ins, followed by the release of Cys-GlcN-Ins and AMP. The steady-state kinetic parameters were determined to be kcat equal to 3.15 s-1, and Km values of 1.8, 0.1, and 0.16 mM for ATP, cysteine, and GlcN-Ins, respectively. A stable bisubstrate analogue, 5'-O-[N-(l-cysteinyl)sulfamonyl]adenosine, exhibits competitive inhibition versus ATP and noncompetitive inhibition versus cysteine, with an inhibition constant of approximately 306 nM versus ATP. Single-turnover reactions of the first and second half reactions were determined using rapid-quench techniques, giving rates of approximately 9.4 and approximately 5.2 s-1, respectively, consistent with the cysteinyl adenylate being a kinetically competent intermediate in the reaction by MshC.
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Affiliation(s)
- Fan Fan
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461
| | - Andreas Luxenburger
- Carbohydrate Chemistry Team, Industrial Research Limited, PO Box 31-310, Lower Hutt, New Zealand
| | - Gavin F. Painter
- Carbohydrate Chemistry Team, Industrial Research Limited, PO Box 31-310, Lower Hutt, New Zealand
| | - John S Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461
- *AUTHOR EMAIL ADDRESS:
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42
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Fadouloglou VE, Deli A, Glykos NM, Psylinakis E, Bouriotis V, Kokkinidis M. Crystal structure of the BcZBP, a zinc-binding protein from Bacillus cereus. FEBS J 2007; 274:3044-54. [PMID: 17501983 DOI: 10.1111/j.1742-4658.2007.05834.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Bacillus cereus is an opportunistic pathogenic bacterium closely related to Bacillus anthracis, the causative agent of anthrax in mammals. A significant portion of the B. cereus chromosomal genes are common to B. anthracis, including genes which in B. anthracis code for putative virulence and surface proteins. B. cereus thus provides a convenient model organism for studying proteins potentially associated with the pathogenicity of the highly infectious B. anthracis. The zinc-binding protein of B. cereus, BcZBP, is encoded from the bc1534 gene which has three homologues to B. anthracis. The protein exhibits deacetylase activity with the N-acetyl moiety of the N-acetylglucosamine and the diacetylchitobiose and triacetylchitotriose. However, neither the specific substrate of the BcZBP nor the biochemical pathway have been conclusively identified. Here, we present the crystal structure of BcZBP at 1.8 A resolution. The N-terminal part of the 234 amino acid protein adopts a Rossmann fold whereas the C-terminal part consists of two beta-strands and two alpha-helices. In the crystal, the protein forms a compact hexamer, in agreement with solution data. A zinc binding site and a potential active site have been identified in each monomer. These sites have extensive similarities to those found in two known zinc-dependent hydrolases with deacetylase activity, MshB and LpxC, despite a low degree of amino acid sequence identity. The functional implications and a possible catalytic mechanism are discussed.
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Truman AW, Huang F, Llewellyn NM, Spencer JB. Characterization of the enzyme BtrD from Bacillus circulans and revision of its functional assignment in the biosynthesis of butirosin. Angew Chem Int Ed Engl 2007; 46:1462-4. [PMID: 17226887 DOI: 10.1002/anie.200604194] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Andrew W Truman
- University of Cambridge, University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW, UK
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Abstract
The pseudodisaccharide mycothiol is present in millimolar levels as the dominant thiol in most species of Actinomycetales. The primary role of mycothiol is to maintain the intracellular redox homeostasis. As such, it acts as an electron acceptor/donor and serves as a cofactor in detoxification reactions for alkylating agents, free radicals and xenobiotics. In addition, like glutathione, mycothiol may be involved in catabolic processes with an essential role for growth on recalcitrant chemicals such as aromatic compounds. Following a little over a decade of research since the discovery of mycothiol in 1994, we summarize the current knowledge about the role of mycothiol as an enzyme cofactor and consider possible mycothiol-dependent enzymes.
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Affiliation(s)
- Mamta Rawat
- Department of Biology, California State University - Fresno, Fresno, California 93704, USA.
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45
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Truman A, Huang F, Llewellyn N, Spencer J. Characterization of the Enzyme BtrD fromBacillus circulans and Revision of Its Functional Assignment in the Biosynthesis of Butirosin. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200604194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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46
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Truman AW, Robinson L, Spencer JB. Identification of a Deacetylase Involved in the Maturation of Teicoplanin. Chembiochem 2006; 7:1670-5. [PMID: 17009278 DOI: 10.1002/cbic.200600308] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Andrew W Truman
- University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
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47
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Newton GL, Ta P, Bzymek KP, Fahey RC. Biochemistry of the initial steps of mycothiol biosynthesis. J Biol Chem 2006; 281:33910-20. [PMID: 16940050 DOI: 10.1074/jbc.m604724200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mycothiol is the major thiol produced by mycobacteria and is required for growth of Mycobacterium tuberculosis. The final three steps in the biosynthesis of mycothiol have been fully elucidated but the initial steps have been unclear. A glycosyltransferase, MshA, is required for production of the mycothiol precursor, 1-O-(2-acetamido-2-deoxy-alpha-D-glucopyranosyl)-D-myo-inositol, but its substrates and immediate products were unknown. In this study, we show that the N-acetylglucosamine donor is UDP-N-acetylglucosamine and that the N-acetylglucosamine acceptor is 1L-myo-inositol 1-phosphate. The reaction generates UDP and 1-O-(2-acetamido-2-deoxy-alpha-D-glucopyranosyl)-D-myo-inositol 3-phosphate. Using cell-free extracts of M. smegmatis mc(2)155, little activity was obtained with myo-inositol, 1D-myo-inositol 1-phosphate, or myo-inositol 2-phosphate as the N-acetylglucosamine acceptor. A phosphatase, designated MshA2, is required to dephosphorylate 1-O-(2-acetamido-2-deoxy-alpha-glucopyranosyl)-D-myo-inositol 3-phosphate to produce 1-O-(2-acetamido-2-deoxy-alpha-D-glucopyranosyl)-D-myo-inositol. The latter is deacetylated, ligated with cysteine, and the cysteinyl amino group acetylated by acetyl-CoA to complete the mycothiol biosynthesis pathway. Uptake and concentration of myo-[14C]inositol is rapid in Mycobacterium smegmatis and leads to production of radiolabeled inositol 1-phosphate and mycothiol. This demonstrates the presence of a myo-inositol transporter and a kinase that generates 1L-myo-inositol 1-phosphate. The biochemical pathway of mycothiol biosynthesis is now fully elucidated.
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Affiliation(s)
- Gerald L Newton
- Department of Chemistry and Biochemistry, University of California, La Jolla, California 92093, USA
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Gennadios HA, Whittington DA, Li X, Fierke CA, Christianson DW. Mechanistic inferences from the binding of ligands to LpxC, a metal-dependent deacetylase. Biochemistry 2006; 45:7940-8. [PMID: 16800620 PMCID: PMC2505344 DOI: 10.1021/bi060823m] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The metal-dependent deacetylase LpxC catalyzes the first committed step of lipid A biosynthesis in Gram-negative bacteria. Accordingly, LpxC is an attractive target for the development of inhibitors that may serve as potential new antibiotics for the treatment of Gram-negative bacterial infections. Here, we report the 2.7 A resolution X-ray crystal structure of LpxC complexed with the substrate analogue inhibitor TU-514 and the 2.0 A resolution structure of LpxC complexed with imidazole. The X-ray crystal structure of LpxC complexed with TU-514 allows for a detailed examination of the coordination geometry of the catalytic zinc ion and other enzyme-inhibitor interactions in the active site. The hydroxamate group of TU-514 forms a bidentate chelate complex with the zinc ion and makes hydrogen bond interactions with conserved active site residues E78, H265, and T191. The inhibitor C-4 hydroxyl group makes direct hydrogen bond interactions with E197 and H58. Finally, the C-3 myristate moiety of the inhibitor binds in the hydrophobic tunnel of the active site. These intermolecular interactions provide a foundation for understanding structural aspects of enzyme-substrate and enzyme-inhibitor affinity. Comparison of the TU-514 complex with cacodylate and imidazole complexes suggests a possible substrate diphosphate binding site and highlights residues that may stabilize the tetrahedral intermediate and its flanking transition states in catalysis. Evidence of a catalytic zinc ion in the native zinc enzyme coordinated by H79, H238, D242, and two water molecules with square pyramidal geometry is also presented. These results suggest that the native state of this metallohydrolase may contain a pentacoordinate zinc ion, which contrasts with the native states of archetypical zinc hydrolases such as thermolysin and carboxypeptidase A.
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Affiliation(s)
| | | | | | | | - David W. Christianson
- To whom correspondence should be addressed. Telephone: (215) 898-5714. Fax: (215) 573-2201.
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Newton GL, Ko M, Ta P, Av-Gay Y, Fahey RC. Purification and characterization of Mycobacterium tuberculosis 1d-myo-inosityl-2-acetamido-2-deoxy-α-d-glucopyranoside deacetylase, MshB, a mycothiol biosynthetic enzyme. Protein Expr Purif 2006; 47:542-50. [PMID: 16630724 DOI: 10.1016/j.pep.2006.03.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 02/28/2006] [Accepted: 03/06/2006] [Indexed: 11/26/2022]
Abstract
Mycothiol (MSH, AcCys-GlcN-Ins) is the major low molecular weight thiol in actinomycetes and is essential for growth of Mycobacterium tuberculosis. MshB, the GlcNAc-Ins deacetylase, is a key enzyme in MSH biosynthesis. MshB from M. tuberculosis was cloned, expressed, purified, and its properties characterized. Values of k(cat) and K(m) for MshB were determined for the biological substrate, GlcNAc-Ins, and several other good substrates. The substrate specificity of MshB was compared to that of M. tuberculosis mycothiol S-conjugate amidase (Mca), a homologous enzyme having weak GlcNAc-Ins deacetylase activity. Both enzymes are metalloamidases with overlapping amidase activity toward mycothiol S-conjugates (AcCySR-GlcN-Ins). The Ins residue and hydrophobic R groups enhance the activity with both MshB and Mca, but changes in the acyl group attached to GlcN have opposite effects on the two enzymes.
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Affiliation(s)
- Gerald L Newton
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, 92093, USA
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50
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Pick N, Rawat M, Arad D, Lan J, Fan J, Kende AS, Av-Gay Y. In vitro properties of antimicrobial bromotyrosine alkaloids. J Med Microbiol 2006; 55:407-415. [PMID: 16533988 DOI: 10.1099/jmm.0.46319-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A bromotyrosine alkaloid family of antimicrobial agents was synthesized using the known structure of a natural inhibitor of the mycobacterial mycothiol S-conjugate amidase (MCA) as a template. This series of compounds represents a novel class of anti-infective agents against Gram-positive pathogens, including mycobacteria and meticillin- and vancomycin-resistant Staphylococcus aureus. The fact that these compounds are active against mycobacterial strains in which the MCA gene is deleted and against Gram-positive bacteria lacking mycothiol suggests the existence of an alternative target for these compounds. One member of this family, EXEG1706, was identified as the lead compound possessing low MICs (2.5-25 microg ml(-1)) for several clinical isolates, whilst having low toxicity for THP-1 monocytes and macrophages.
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Affiliation(s)
- Neora Pick
- Division of Infectious Diseases, University of British Columbia, Vancouver, BC V5Z 3J5, Canada
| | - Mamta Rawat
- Department of Biology, California State University - Fresno, Fresno, CA 937401, USA
- Division of Infectious Diseases, University of British Columbia, Vancouver, BC V5Z 3J5, Canada
| | - Dorit Arad
- Division of Infectious Diseases, University of British Columbia, Vancouver, BC V5Z 3J5, Canada
| | - Jiong Lan
- Department of Chemistry, University of Rochester, Rochester, NY 14627-0216, USA
| | - Junfa Fan
- Department of Chemistry, University of Rochester, Rochester, NY 14627-0216, USA
| | - Andrew S Kende
- Department of Chemistry, University of Rochester, Rochester, NY 14627-0216, USA
| | - Yossef Av-Gay
- Division of Infectious Diseases, University of British Columbia, Vancouver, BC V5Z 3J5, Canada
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