1
|
Dokladda K, Billamas P, Jaitrong S, Suwanakitti N, Phornsiricharoenphant W, Viratyosin W, Prammananan T. Whole genome sequencing reveals candidate genes involving in PAS resistance in M. Tuberculosis isolated from patients in Thailand. World J Microbiol Biotechnol 2023; 40:32. [PMID: 38057660 DOI: 10.1007/s11274-023-03834-7] [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: 07/03/2023] [Accepted: 11/10/2023] [Indexed: 12/08/2023]
Abstract
Para-amino salicylic acid (PAS) was first reported by Lehmann in 1946 and used for tuberculosis treatment. However, due to its adverse effects, it is now used only as a second line anti-tuberculosis drug for treatment of multidrug resistant or extensively drug resistant M. tuberculosis. The structure of PAS is similar to para-amino benzoic acid (pABA), an intermediate metabolite in the folate synthesis pathway. The study has identified mutations in genes in folate pathway and their intergenic regions for their possibilities in responsible for PAS resistance. Genomic DNA from 120 PAS-resistant and 49 PAS-sensitive M. tuberculosis isolated from tuberculosis patients in Thailand were studied by whole genome sequencing. Twelve genes in the folate synthesis pathway were investigated for variants associated with PAS resistance. Fifty-one SNVs were found in nine genes and their intergenic regions (pabC, pabB, folC, ribD, thyX, dfrA, thyA, folK, folP). Functional correlation test confirmed mutations in RibD, ThyX, and ThyA are responsible for PAS resistance. Detection of mutation in thyA, folC, intergenic regions of thyX, ribD, and double deletion of thyA dfrA are proposed for determination of PAS resistant M. tuberculosis.
Collapse
Affiliation(s)
- Kanchana Dokladda
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand.
| | - Pamaree Billamas
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Sarinya Jaitrong
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Nattida Suwanakitti
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Worawich Phornsiricharoenphant
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Wasna Viratyosin
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Therdsak Prammananan
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| |
Collapse
|
2
|
Hegde PV, Howe MD, Zimmerman MD, Boshoff HIM, Sharma S, Remache B, Jia Z, Pan Y, Baughn AD, Dartois V, Aldrich CC. Synthesis and biological evaluation of orally active prodrugs and analogs of para-aminosalicylic acid (PAS). Eur J Med Chem 2022; 232:114201. [PMID: 35219151 PMCID: PMC8941652 DOI: 10.1016/j.ejmech.2022.114201] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/10/2022] [Accepted: 02/12/2022] [Indexed: 11/26/2022]
Abstract
Tuberculosis (TB) is one of the world's most deadly infectious diseases resulting in nearly 1.3 million deaths annually and infecting nearly one-quarter of the population. para-Aminosalicylic acid (PAS), an important second-line agent for treating drug-resistant Mycobacterium tuberculosis, has moderate bioavailability and rapid clearance that necessitate high daily doses of up to 12 g per day, which in turn causes severe gastrointestinal disturbances presumably by disruption of gut microbiota and host epithelial cells. We first synthesized a series of alkyl, acyloxy and alkyloxycarbonyloxyalkyl ester prodrugs to increase the oral bioavailability and thereby prevent intestinal accumulation as well as undesirable bioactivation by the gut microbiome to non-natural folate species that exhibit cytotoxicity. The pivoxyl prodrug of PAS was superior to all of the prodrugs examined and showed nearly quantitative absorption. While the conceptually simple prodrug approach improved the oral bioavailability of PAS, it did not address the intrinsic rapid clearance of PAS mediated by N-acetyltransferase-1 (NAT-1). Thus, we next modified the PAS scaffold to reduce NAT-1 catalyzed inactivation by introduction of groups to sterically block N-acetylation and fluorination of the aryl ring of PAS to attenuate N-acetylation by electronically deactivating the para-amino group. Among the mono-fluorinated analogs prepared, 5-fluoro-PAS, exhibited the best activity and an 11-fold decreased rate of inactivation by NAT-1 that translated to a 5-fold improved exposure as measured by area-under-the-curve (AUC) following oral dosing to CD-1 mice. The pivoxyl prodrug and fluorination at the 5-position of PAS address the primary limitations of PAS and have the potential to revitalize this second-line TB drug.
Collapse
Affiliation(s)
- Pooja V Hegde
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Michael D Howe
- Department of Microbiology & Immunology, University of Minnesota, Minneapolis, MN, USA
| | - Matthew D Zimmerman
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, USA
| | - Helena I M Boshoff
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA
| | - Sachin Sharma
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Brianna Remache
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, USA
| | - Ziyi Jia
- Department of Microbiology & Immunology, University of Minnesota, Minneapolis, MN, USA
| | - Yan Pan
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, USA
| | - Anthony D Baughn
- Department of Microbiology & Immunology, University of Minnesota, Minneapolis, MN, USA
| | - Veronique Dartois
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, USA
| | - Courtney C Aldrich
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA.
| |
Collapse
|
3
|
Singh A, Gupta AK, Singh S. Molecular Mechanisms of Drug Resistance in Mycobacterium tuberculosis: Role of Nanoparticles Against Multi-drug-Resistant Tuberculosis (MDR-TB). Nanobiomedicine (Rij) 2020. [DOI: 10.1007/978-981-32-9898-9_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
4
|
Bouz G, Juhás M, Pausas Otero L, Paredes de la Red C, Janďourek O, Konečná K, Paterová P, Kubíček V, Janoušek J, Doležal M, Zitko J. Substituted N-(Pyrazin-2-yl)benzenesulfonamides; Synthesis, Anti-Infective Evaluation, Cytotoxicity, and In Silico Studies. Molecules 2019; 25:E138. [PMID: 31905775 PMCID: PMC6982817 DOI: 10.3390/molecules25010138] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 12/21/2019] [Accepted: 12/26/2019] [Indexed: 12/22/2022] Open
Abstract
We prepared a series of substituted N-(pyrazin-2-yl)benzenesulfonamides as an attempt to investigate the effect of different linkers connecting pyrazine to benzene cores on antimicrobial activity when compared to our previous compounds of amide or retro-amide linker type. Only two compounds, 4-amino-N-(pyrazin-2-yl)benzenesulfonamide (MIC = 6.25 μg/mL, 25 μM) and 4-amino-N-(6-chloropyrazin-2-yl)benzenesulfonamide (MIC = 6.25 μg/mL, 22 μM) exerted good antitubercular activity against M. tuberculosis H37Rv. However, they were excluded from the comparison as they-unlike the other compounds-possessed the pharmacophore for the inhibition of folate pathway, which was proven by docking studies. We performed target fishing, where we identified matrix metalloproteinase-8 as a promising target for our title compounds that is worth future exploration.
Collapse
Affiliation(s)
- Ghada Bouz
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Martin Juhás
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Lluis Pausas Otero
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Cristina Paredes de la Red
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Ondřej Janďourek
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Klára Konečná
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Pavla Paterová
- Department of Clinical Microbiology, University Hospital, Sokolská 581, 500 05 Hradec Králové, Czech Republic;
| | - Vladimír Kubíček
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Jiří Janoušek
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Martin Doležal
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| | - Jan Zitko
- Faculty of Pharmacy in Hradec Králové, Charles University, Heyrovského 1203, 50005 Hradec Králové, Czech Republic; (M.J.); (L.P.O.); (C.P.d.l.R.); (O.J.); (K.K.); (V.K.); (J.J.); (M.D.)
| |
Collapse
|
5
|
Analysis of mutations leading to para-aminosalicylic acid resistance in Mycobacterium tuberculosis. Sci Rep 2019; 9:13617. [PMID: 31541138 PMCID: PMC6754364 DOI: 10.1038/s41598-019-48940-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/31/2019] [Indexed: 12/18/2022] Open
Abstract
Thymidylate synthase A (ThyA) is the key enzyme involved in the folate pathway in Mycobacterium tuberculosis. Mutation of key residues of ThyA enzyme which are involved in interaction with substrate 2′-deoxyuridine-5′-monophosphate (dUMP), cofactor 5,10-methylenetetrahydrofolate (MTHF), and catalytic site have caused para-aminosalicylic acid (PAS) resistance in TB patients. Focusing on R127L, L143P, C146R, L172P, A182P, and V261G mutations, including wild-type, we performed long molecular dynamics (MD) simulations in explicit solvent to investigate the molecular principles underlying PAS resistance due to missense mutations. We found that these mutations lead to (i) extensive changes in the dUMP and MTHF binding sites, (ii) weak interaction of ThyA enzyme with dUMP and MTHF by inducing conformational changes in the structure, (iii) loss of the hydrogen bond and other atomic interactions and (iv) enhanced movement of protein atoms indicated by principal component analysis (PCA). In this study, MD simulations framework has provided considerable insight into mutation induced conformational changes in the ThyA enzyme of Mycobacterium.
Collapse
|
6
|
Kordus SL, Baughn AD. Revitalizing antifolates through understanding mechanisms that govern susceptibility and resistance. MEDCHEMCOMM 2019; 10:880-895. [PMID: 31303985 PMCID: PMC6595967 DOI: 10.1039/c9md00078j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 05/07/2019] [Indexed: 12/12/2022]
Abstract
In prokaryotes and eukaryotes, folate (vitamin B9) is an essential metabolic cofactor required for all actively growing cells. Specifically, folate serves as a one-carbon carrier in the synthesis of amino acids (such as methionine, serine, and glycine), N-formylmethionyl-tRNA, coenzyme A, purines and thymidine. Many microbes are unable to acquire folates from their environment and rely on de novo folate biosynthesis. In contrast, mammals lack the de novo folate biosynthesis pathway and must obtain folate from commensal microbiota or the environment using proton-coupled folate transporters. The essentiality and dichotomy between mammalian and bacterial folate biosynthesis and utilization pathways make it an ideal drug target for the development of antimicrobial agents and cancer chemotherapeutics. In this minireview, we discuss general aspects of folate biosynthesis and the underlying mechanisms that govern susceptibility and resistance of organisms to antifolate drugs.
Collapse
Affiliation(s)
- Shannon Lynn Kordus
- Department of Microbiology and Immunology , University of Minnesota , Minneapolis , MN , USA .
| | - Anthony David Baughn
- Department of Microbiology and Immunology , University of Minnesota , Minneapolis , MN , USA .
| |
Collapse
|
7
|
Miryala SK, Anbarasu A, Ramaiah S. Impact of bedaquiline and capreomycin on the gene expression patterns of multidrug‐resistant
Mycobacterium tuberculosis
H37Rv strain and understanding the molecular mechanism of antibiotic resistance. J Cell Biochem 2019; 120:14499-14509. [DOI: 10.1002/jcb.28711] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 03/06/2019] [Accepted: 03/15/2019] [Indexed: 01/03/2023]
Affiliation(s)
- Sravan Kumar Miryala
- Department of Bio‐Sciences, Medical and Biological Computing Laboratory, School of Bio Sciences and Technology Vellore Institute of Technology Vellore Tamil Nadu India
| | - Anand Anbarasu
- Department of Bio‐Sciences, Medical and Biological Computing Laboratory, School of Bio Sciences and Technology Vellore Institute of Technology Vellore Tamil Nadu India
| | - Sudha Ramaiah
- Department of Bio‐Sciences, Medical and Biological Computing Laboratory, School of Bio Sciences and Technology Vellore Institute of Technology Vellore Tamil Nadu India
| |
Collapse
|
8
|
Rode HB, Lade DM, Grée R, Mainkar PS, Chandrasekhar S. Strategies towards the synthesis of anti-tuberculosis drugs. Org Biomol Chem 2019; 17:5428-5459. [DOI: 10.1039/c9ob00817a] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this report, we reviewed the strategies towards the synthesis of anti-tuberculosis drugs. They include semisynthetic approaches, resolution based strategies, microbial transformations, solid phase synthesis, and asymmetric synthesis.
Collapse
Affiliation(s)
- Haridas B. Rode
- Department of Organic Synthesis and Process Chemistry
- CSIR-Indian Institute of Chemical Technology
- Hyderabad-500007
- India
- Academy of Scientific and Innovative Research (AcSIR)
| | - Dhanaji M. Lade
- Department of Organic Synthesis and Process Chemistry
- CSIR-Indian Institute of Chemical Technology
- Hyderabad-500007
- India
- Academy of Scientific and Innovative Research (AcSIR)
| | - René Grée
- University of Rennes
- CNRS
- ISCR (Institut des Sciences Chimiques de Rennes)
- UMR 6226
- F-35000 Rennes
| | - Prathama S. Mainkar
- Department of Organic Synthesis and Process Chemistry
- CSIR-Indian Institute of Chemical Technology
- Hyderabad-500007
- India
- Academy of Scientific and Innovative Research (AcSIR)
| | - Srivari Chandrasekhar
- Department of Organic Synthesis and Process Chemistry
- CSIR-Indian Institute of Chemical Technology
- Hyderabad-500007
- India
- Academy of Scientific and Innovative Research (AcSIR)
| |
Collapse
|
9
|
Awasthi D, Freundlich JS. Antimycobacterial Metabolism: Illuminating Mycobacterium tuberculosis Biology and Drug Discovery. Trends Microbiol 2017. [PMID: 28622844 DOI: 10.1016/j.tim.2017.05.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Bacteria are capable of performing a number of biotransformations that may activate or deactivate xenobiotics. Recent efforts have utilized metabolomics techniques to study the fate of small-molecule antibacterials within the targeted organism. Examples involving Mycobacterium tuberculosis are reviewed and analyzed with regard to the insights they provide as to both activation and deactivation of the antibacterial. The studies, in particular, shed light on biosynthetic transformations performed by M. tuberculosis while suggesting avenues for the evolution of chemical tools, highlighting potential areas for drug discovery, and mechanisms of approved drugs. A two-pronged approach investigating the metabolism of antibacterials within both the host and bacterium is outlined and will be of value to both the chemical biology and drug discovery fields.
Collapse
Affiliation(s)
- Divya Awasthi
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University - New Jersey Medical School, Newark, NJ, USA
| | - Joel S Freundlich
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University - New Jersey Medical School, Newark, NJ, USA; Division of Infectious Disease, Department of Medicine, and the Ruy V. Lourenco Center for the Study of Emerging and Reemerging Pathogens, Rutgers University - New Jersey Medical School, Newark, NJ, USA.
| |
Collapse
|
10
|
Targeting intracellular p-aminobenzoic acid production potentiates the anti-tubercular action of antifolates. Sci Rep 2016; 6:38083. [PMID: 27905500 PMCID: PMC5131483 DOI: 10.1038/srep38083] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 11/03/2016] [Indexed: 12/18/2022] Open
Abstract
The ability to revitalize and re-purpose existing drugs offers a powerful approach for novel treatment options against Mycobacterium tuberculosis and other infectious agents. Antifolates are an underutilized drug class in tuberculosis (TB) therapy, capable of disrupting the biosynthesis of tetrahydrofolate, an essential cellular cofactor. Based on the observation that exogenously supplied p-aminobenzoic acid (PABA) can antagonize the action of antifolates that interact with dihydropteroate synthase (DHPS), such as sulfonamides and p-aminosalicylic acid (PAS), we hypothesized that bacterial PABA biosynthesis contributes to intrinsic antifolate resistance. Herein, we demonstrate that disruption of PABA biosynthesis potentiates the anti-tubercular action of DHPS inhibitors and PAS by up to 1000 fold. Disruption of PABA biosynthesis is also demonstrated to lead to loss of viability over time. Further, we demonstrate that this strategy restores the wild type level of PAS susceptibility in a previously characterized PAS resistant strain of M. tuberculosis. Finally, we demonstrate selective inhibition of PABA biosynthesis in M. tuberculosis using the small molecule MAC173979. This study reveals that the M. tuberculosis PABA biosynthetic pathway is responsible for intrinsic resistance to various antifolates and this pathway is a chemically vulnerable target whose disruption could potentiate the tuberculocidal activity of an underutilized class of antimicrobial agents.
Collapse
|
11
|
Ramakrishnan G, Chandra NR, Srinivasan N. Recognizing drug targets using evolutionary information: implications for repurposing FDA-approved drugs against Mycobacterium tuberculosis H37Rv. MOLECULAR BIOSYSTEMS 2016; 11:3316-31. [PMID: 26429199 DOI: 10.1039/c5mb00476d] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Drug repurposing to explore target space has been gaining pace over the past decade with the upsurge in the use of systematic approaches for computational drug discovery. Such a cost and time-saving approach gains immense importance for pathogens of special interest, such as Mycobacterium tuberculosis H37Rv. We report a comprehensive approach to repurpose drugs, based on the exploration of evolutionary relationships inferred from the comparative sequence and structural analyses between targets of FDA-approved drugs and the proteins of M. tuberculosis. This approach has facilitated the identification of several polypharmacological drugs that could potentially target unexploited M. tuberculosis proteins. A total of 130 FDA-approved drugs, originally intended against other diseases, could be repurposed against 78 potential targets in M. tuberculosis. Additionally, we have also made an attempt to augment the chemical space by recognizing compounds structurally similar to FDA-approved drugs. For three of the attractive cases we have investigated the probable binding modes of the drugs in their corresponding M. tuberculosis targets by means of structural modelling. Such prospective targets and small molecules could be prioritized for experimental endeavours, and could significantly influence drug-discovery and drug-development programmes for tuberculosis.
Collapse
Affiliation(s)
- Gayatri Ramakrishnan
- Indian Institute of Science Mathematics Initiative, Indian Institute of Science, Bangalore-560012, India and Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560012, India.
| | - Nagasuma R Chandra
- Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | | |
Collapse
|
12
|
Pornthanakasem W, Riangrungroj P, Chitnumsub P, Ittarat W, Kongkasuriyachai D, Uthaipibull C, Yuthavong Y, Leartsakulpanich U. Role of Plasmodium vivax Dihydropteroate Synthase Polymorphisms in Sulfa Drug Resistance. Antimicrob Agents Chemother 2016; 60:4453-63. [PMID: 27161627 PMCID: PMC4958149 DOI: 10.1128/aac.01835-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 04/19/2016] [Indexed: 11/20/2022] Open
Abstract
Dihydropteroate synthase (DHPS) is a known sulfa drug target in malaria treatment, existing as a bifunctional enzyme together with hydroxymethyldihydropterin pyrophosphokinase (HPPK). Polymorphisms in key residues of Plasmodium falciparum DHPS (PfDHPS) have been characterized and linked to sulfa drug resistance in malaria. Genetic sequencing of P. vivax dhps (Pvdhps) from clinical isolates has shown several polymorphisms at the positions equivalent to those in the Pfdhps genes conferring sulfa drug resistance, suggesting a mechanism for sulfa drug resistance in P. vivax similar to that seen in P. falciparum To characterize the role of polymorphisms in the PvDHPS in sulfa drug resistance, various mutants of recombinant PvHPPK-DHPS enzymes were expressed and characterized. Moreover, due to the lack of a continuous in vitro culture system for P. vivax parasites, a surrogate P. berghei model expressing Pvhppk-dhps genes was established to demonstrate the relationship between sequence polymorphisms and sulfa drug susceptibility and to test the activities of PvDHPS inhibitors on the transgenic parasites. Both enzyme activity and transgenic parasite growth were sensitive to sulfadoxine to different degrees, depending on the number of mutations that accumulated in DHPS. Ki values and 50% effective doses were higher for mutant PvDHPS enzymes than the wild-type enzymes. Altogether, the study provides the first evidence of sulfa drug resistance at the molecular level in P. vivax Furthermore, the enzyme inhibition assay and the in vivo screening system can be useful tools for screening new compounds for their activities against PvDHPS.
Collapse
Affiliation(s)
| | | | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, Pathum Thani, Thailand
| | - Wanwipa Ittarat
- National Center for Genetic Engineering and Biotechnology, Pathum Thani, Thailand
| | | | - Chairat Uthaipibull
- National Center for Genetic Engineering and Biotechnology, Pathum Thani, Thailand
| | - Yongyuth Yuthavong
- National Center for Genetic Engineering and Biotechnology, Pathum Thani, Thailand
| | | |
Collapse
|
13
|
Nguyen L. Antibiotic resistance mechanisms in M. tuberculosis: an update. Arch Toxicol 2016; 90:1585-604. [PMID: 27161440 DOI: 10.1007/s00204-016-1727-6] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/27/2016] [Indexed: 12/16/2022]
Abstract
Treatment of tuberculosis (TB) has been a therapeutic challenge because of not only the naturally high resistance level of Mycobacterium tuberculosis to antibiotics but also the newly acquired mutations that confer further resistance. Currently standardized regimens require patients to daily ingest up to four drugs under direct observation of a healthcare worker for a period of 6-9 months. Although they are quite effective in treating drug susceptible TB, these lengthy treatments often lead to patient non-adherence, which catalyzes for the emergence of M. tuberculosis strains that are increasingly resistant to the few available anti-TB drugs. The rapid evolution of M. tuberculosis, from mono-drug-resistant to multiple drug-resistant, extensively drug-resistant and most recently totally drug-resistant strains, is threatening to make TB once again an untreatable disease if new therapeutic options do not soon become available. Here, I discuss the molecular mechanisms by which M. tuberculosis confers its profound resistance to antibiotics. This knowledge may help in developing novel strategies for weakening drug resistance, thus enhancing the potency of available antibiotics against both drug susceptible and resistant M. tuberculosis strains.
Collapse
Affiliation(s)
- Liem Nguyen
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
| |
Collapse
|
14
|
Minato Y, Thiede JM, Kordus SL, McKlveen EJ, Turman BJ, Baughn AD. Mycobacterium tuberculosis folate metabolism and the mechanistic basis for para-aminosalicylic acid susceptibility and resistance. Antimicrob Agents Chemother 2015; 59:5097-106. [PMID: 26033719 PMCID: PMC4538520 DOI: 10.1128/aac.00647-15] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
para-Aminosalicylic acid (PAS) entered clinical use in 1946 as the second exclusive drug for the treatment of tuberculosis (TB). While PAS was initially a first-line TB drug, the introduction of more potent antitubercular agents relegated PAS to the second-line tier of agents used for the treatment of drug-resistant Mycobacterium tuberculosis infections. Despite the long history of PAS usage, an understanding of the molecular and biochemical mechanisms governing the susceptibility and resistance of M. tuberculosis to this drug has lagged behind that of most other TB drugs. Herein, we discuss previous studies that demonstrate PAS-mediated disruption of iron acquisition, as well as recent genetic, biochemical, and metabolomic studies that have revealed that PAS is a prodrug that ultimately corrupts one-carbon metabolism through inhibition of the formation of reduced folate species. We also discuss findings from laboratory and clinical isolates that link alterations in folate metabolism to PAS resistance. These advancements in our understanding of the basis of the susceptibility and resistance of M. tuberculosis to PAS will enable the development of novel strategies to revitalize this and other antimicrobial agents for use in the global effort to eradicate TB.
Collapse
Affiliation(s)
- Yusuke Minato
- Department of Microbiology, Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Joshua M Thiede
- Department of Microbiology, Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Shannon Lynn Kordus
- Department of Microbiology, Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Edward J McKlveen
- Department of Chemistry, Harvard University, Cambridge, Massachusetts, USA
| | - Breanna J Turman
- Department of Microbiology, Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Anthony D Baughn
- Department of Microbiology, Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| |
Collapse
|
15
|
Chaitanya S, Das M, Bhat P, Ebenezer M. Computational Modelling of Dapsone Interaction With Dihydropteroate Synthase inMycobacterium leprae; Insights Into Molecular Basis of Dapsone Resistance in Leprosy. J Cell Biochem 2015; 116:2293-303. [DOI: 10.1002/jcb.25180] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 03/31/2015] [Indexed: 01/20/2023]
Affiliation(s)
- Sundeep Chaitanya
- Research Officer; Department of Laboratories; Molecular Biology and Immunology Division; The Schieffelin Institute of Health-Research and Leprosy Center (SIH-R&LC); Karigiri; Vellore Tamil Nadu 632106 India
| | - Madhusmita Das
- Research Officer; Department of Laboratories; Molecular Biology and Immunology Division; The Schieffelin Institute of Health-Research and Leprosy Center (SIH-R&LC); Karigiri; Vellore Tamil Nadu 632106 India
| | - Pritesh Bhat
- Applications Scientist; Schrodinger, Inc.; Near KMWA Vidya Niketan; Mahalakshmipuram; Bangalore 560 086 India
| | - Mannam Ebenezer
- The Schieffelin Institute of Health-Research and Leprosy Center (SIH-R&LC); Karigiri; Vellore Tamil Nadu 632106 India
| |
Collapse
|
16
|
Shaw GX, Li Y, Shi G, Wu Y, Cherry S, Needle D, Zhang D, Tropea JE, Waugh DS, Yan H, Ji X. Structural enzymology and inhibition of the bi-functional folate pathway enzyme HPPK-DHPS from the biowarfare agent Francisella tularensis. FEBS J 2014; 281:4123-37. [PMID: 24975935 PMCID: PMC5600157 DOI: 10.1111/febs.12896] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 06/20/2014] [Accepted: 06/25/2014] [Indexed: 11/29/2022]
Abstract
UNLABELLED Two valid targets for antibiotic development, 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) and dihydropteroate synthase (DHPS), catalyze consecutive reactions in folate biosynthesis. In Francisella tularensis (Ft), these two activities are contained in a single protein, FtHPPK-DHPS. Although Pemble et al. (PLoS One 5, e14165) determined the structure of FtHPPK-DHPS, they were unable to measure the kinetic parameters of the enzyme. In this study, we elucidated the binding and inhibitory activities of two HPPK inhibitors (HP-18 and HP-26) against FtHPPK-DHPS, determined the structure of FtHPPK-DHPS in complex with HP-26, and measured the kinetic parameters for the dual enzymatic activities of FtHPPK-DHPS. The biochemical analyses showed that HP-18 and HP-26 have significant isozyme selectivity, and that FtHPPK-DHPS is unique in that the catalytic efficiency of its DHPS activity is only 1/260,000 of that of Escherichia coli DHPS. Sequence and structural analyses suggest that HP-26 is an excellent lead for developing therapeutic agents for tularemia, and that the very low DHPS activity is due, at least in part, to the lack of a key residue that interacts with the substrate p-aminobenzoic acid (pABA). A BLAST search of the genomes of ten F. tularensis strains indicated that the bacterium contains a single FtHPPK-DHPS. The marginal DHPS activity and the single copy existence of FtHPPK-DHPS in F. tularensis make this bacterium more vulnerable to DHPS inhibitors. Current sulfa drugs are ineffective against tularemia; new inhibitors targeting the unique pABA-binding pocket may be effective and less subject to resistance because any mutations introducing resistance may make the marginal DHPS activity unable to support the growth of F. tularensis. DATABASE The coordinates and structure factors have been deposited in the Protein Data Bank under accession code 4PZV.
Collapse
Affiliation(s)
- Gary X. Shaw
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Yue Li
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Genbin Shi
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Yan Wu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Scott Cherry
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Danielle Needle
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Di Zhang
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Joseph E. Tropea
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - David S. Waugh
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Honggao Yan
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Xinhua Ji
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD, USA
| |
Collapse
|
17
|
Tomioka H, Tatano Y, Yasumoto K, Shimizu T. Recent advances in antituberculous drug development and novel drug targets. Expert Rev Respir Med 2014; 2:455-71. [DOI: 10.1586/17476348.2.4.455] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
18
|
Binding pocket alterations in dihydrofolate synthase confer resistance to para-aminosalicylic acid in clinical isolates of Mycobacterium tuberculosis. Antimicrob Agents Chemother 2013; 58:1479-87. [PMID: 24366731 DOI: 10.1128/aac.01775-13] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The mechanistic basis for the resistance of Mycobacterium tuberculosis to para-aminosalicylic acid (PAS), an important agent in the treatment of multidrug-resistant tuberculosis, has yet to be fully defined. As a substrate analog of the folate precursor para-aminobenzoic acid, PAS is ultimately bioactivated to hydroxy dihydrofolate, which inhibits dihydrofolate reductase and disrupts the operation of folate-dependent metabolic pathways. As a result, the mutation of dihydrofolate synthase, an enzyme needed for the bioactivation of PAS, causes PAS resistance in M. tuberculosis strain H37Rv. Here, we demonstrate that various missense mutations within the coding sequence of the dihydropteroate (H2Pte) binding pocket of dihydrofolate synthase (FolC) confer PAS resistance in laboratory isolates of M. tuberculosis and Mycobacterium bovis. From a panel of 85 multidrug-resistant M. tuberculosis clinical isolates, 5 were found to harbor mutations in the folC gene within the H2Pte binding pocket, resulting in PAS resistance. While these alterations in the H2Pte binding pocket resulted in reduced dihydrofolate synthase activity, they also abolished the bioactivation of hydroxy dihydropteroate to hydroxy dihydrofolate. Consistent with this model for abolished bioactivation, the introduction of a wild-type copy of folC fully restored PAS susceptibility in folC mutant strains. Confirmation of this novel PAS resistance mechanism will be beneficial for the development of molecular method-based diagnostics for M. tuberculosis clinical isolates and for further defining the mode of action of this important tuberculosis drug.
Collapse
|
19
|
Gotthard G, Muhammed Ameen S, Drancourt M, Chabriere E. Long-range DHPS mutations unexpectedly increase Mycobacterium chimaera susceptibility to sulfonamides. J Glob Antimicrob Resist 2013; 1:181-188. [DOI: 10.1016/j.jgar.2013.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 05/24/2013] [Indexed: 02/01/2023] Open
|
20
|
Liang X, Wang Z, Wang C, Wen K, Mi T, Zhang J, Zhang S. A proof-of-concept receptor-based assay for sulfonamides. Anal Biochem 2013; 438:110-6. [DOI: 10.1016/j.ab.2013.03.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 03/26/2013] [Accepted: 03/27/2013] [Indexed: 10/27/2022]
|
21
|
Zheng J, Rubin EJ, Bifani P, Mathys V, Lim V, Au M, Jang J, Nam J, Dick T, Walker JR, Pethe K, Camacho LR. para-Aminosalicylic acid is a prodrug targeting dihydrofolate reductase in Mycobacterium tuberculosis. J Biol Chem 2013; 288:23447-56. [PMID: 23779105 DOI: 10.1074/jbc.m113.475798] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
para-Aminosalicylic acid (PAS) is one of the antimycobacterial drugs currently used for multidrug-resistant tuberculosis. Although it has been in clinical use for over 60 years, its mechanism(s) of action remains elusive. Here we report that PAS is a prodrug targeting dihydrofolate reductase (DHFR) through an unusual and novel mechanism of action. We provide evidences that PAS is incorporated into the folate pathway by dihydropteroate synthase (DHPS) and dihydrofolate synthase (DHFS) to generate a hydroxyl dihydrofolate antimetabolite, which in turn inhibits DHFR enzymatic activity. Interestingly, PAS is recognized by DHPS as efficiently as its natural substrate para-amino benzoic acid. Chemical inhibition of DHPS or mutation in DHFS prevents the formation of the antimetabolite, thereby conferring resistance to PAS. In addition, we identified a bifunctional enzyme (riboflavin biosynthesis protein (RibD)), a putative functional analog of DHFR in a knock-out strain. This finding is further supported by the identification of PAS-resistant clinical isolates encoding a RibD overexpression mutation displaying cross-resistance to genuine DHFR inhibitors. Our findings reveal that a metabolite of PAS inhibits DHFR in the folate pathway. RibD was shown to act as a functional analog of DHFR, and as for DHFS, both were shown to be associated in PAS resistance in laboratory strains and clinical isolates.
Collapse
Affiliation(s)
- Jun Zheng
- Novartis Institute for Tropical Diseases, Singapore 138670.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Chakraborty S, Gruber T, Barry CE, Boshoff HI, Rhee KY. Para-aminosalicylic acid acts as an alternative substrate of folate metabolism in Mycobacterium tuberculosis. Science 2013; 339:88-91. [PMID: 23118010 PMCID: PMC3792487 DOI: 10.1126/science.1228980] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Folate biosynthesis is an established anti-infective target, and the antifolate para-aminosalicylic acid (PAS) was one of the first anti-infectives introduced into clinical practice on the basis of target-based drug discovery. Fifty years later, PAS continues to be used to treat tuberculosis. PAS is assumed to inhibit dihydropteroate synthase (DHPS) in Mycobacterium tuberculosis by mimicking the substrate p-aminobenzoate (PABA). However, we found that sulfonamide inhibitors of DHPS inhibited growth of M. tuberculosis only weakly because of their intracellular metabolism. In contrast, PAS served as a replacement substrate for DHPS. Products of PAS metabolism at this and subsequent steps in folate metabolism inhibited those enzymes, competing with their substrates. PAS is thus a prodrug that blocks growth of M. tuberculosis when its active forms are generated by enzymes in the pathway they poison.
Collapse
Affiliation(s)
- Sumit Chakraborty
- Department of Medicine, Weill Cornell Medical College, NY, NY, USA
- Department of Microbiology & Immunology , Weill Cornell Medical College, NY, NY, USA
| | - Todd Gruber
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Clifton E. Barry
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Helena I. Boshoff
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Kyu Y. Rhee
- Department of Medicine, Weill Cornell Medical College, NY, NY, USA
- Department of Microbiology & Immunology , Weill Cornell Medical College, NY, NY, USA
| |
Collapse
|
23
|
Brown-Elliott BA, Nash KA, Wallace RJ. Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria. Clin Microbiol Rev 2012; 25:545-82. [PMID: 22763637 PMCID: PMC3416486 DOI: 10.1128/cmr.05030-11] [Citation(s) in RCA: 335] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria.
Collapse
|
24
|
Seddon JA, Hesseling AC, Marais BJ, McIlleron H, Peloquin CA, Donald PR, Schaaf HS. Paediatric use of second-line anti-tuberculosis agents: a review. Tuberculosis (Edinb) 2011; 92:9-17. [PMID: 22118883 DOI: 10.1016/j.tube.2011.11.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 09/25/2011] [Accepted: 11/01/2011] [Indexed: 11/18/2022]
Abstract
Childhood multidrug-resistant tuberculosis (MDR-TB) is an emerging global epidemic. With the imminent roll-out of rapid molecular diagnostic tests, more children are likely to be identified and require treatment. As MDR-TB is resistant to the most effective first-line drugs, clinicians will have to rely on second-line medications which are less effective and often associated with more pronounced adverse effects than first-line therapy. Despite the fact that most of these agents were discovered many years ago, robust information is lacking regarding their pharmacokinetic and pharmacodynamic properties, adverse effects and drug interactions, especially in children. Children differ from adults in the way that drugs are administered, the manner in which they are metabolised and in the adverse effects experienced. The interaction of these drugs with human immunodeficiency virus infection and antiretroviral therapy is also poorly documented. This article reviews the available second-line drugs currently used in the treatment of MDR-TB in children and discusses medication properties and adverse effects while potential interactions with antiretroviral therapy are explored.
Collapse
Affiliation(s)
- James A Seddon
- Desmond Tutu TB Centre, Faculty of Health Sciences, Stellenbosch University, South Africa.
| | | | | | | | | | | | | |
Collapse
|
25
|
Fivian-Hughes AS, Houghton J, Davis EO. Mycobacterium tuberculosis thymidylate synthase gene thyX is essential and potentially bifunctional, while thyA deletion confers resistance to p-aminosalicylic acid. MICROBIOLOGY-SGM 2011; 158:308-318. [PMID: 22034487 PMCID: PMC3352284 DOI: 10.1099/mic.0.053983-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Thymidylate synthase (TS) enzymes catalyse the biosynthesis of deoxythymidine monophosphate (dTMP or thymidylate), and so are important for DNA replication and repair. Two different types of TS proteins have been described (ThyA and ThyX), which have different enzymic mechanisms and unrelated structures. Mycobacteria are unusual as they encode both thyA and thyX, and the biological significance of this is not yet understood. Mycobacterium tuberculosis ThyX is thought to be essential and a potential drug target. We therefore analysed M. tuberculosis thyA and thyX expression levels, their essentiality and roles in pathogenesis. We show that both thyA and thyX are expressed in vitro, and that this expression significantly increased within murine macrophages. Under all conditions tested, thyA expression exceeded that of thyX. Mutational studies show that M. tuberculosis thyX is essential, confirming that the enzyme is a plausible drug target. The requirement for M. tuberculosis thyX in the presence of thyA implies that the essential function of ThyX is something other than dTM synthesis [corrected].We successfully deleted thyA from the M. tuberculosis genome, and this deletion conferred an in vitro growth defect that was not observed in vivo. Presumably ThyX performs TS activity within M. tuberculosis ΔthyA at a sufficient rate in vivo for normal growth, but the rate in vitro is less than optimal. We also demonstrate that thyA deletion confers M. tuberculosis p-aminosalicylic acid resistance, and show by complementation studies that ThyA T202A and V261G appear to be functional and non-functional, respectively.
Collapse
Affiliation(s)
- Amanda S Fivian-Hughes
- Division of Mycobacterial Research, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Joanna Houghton
- Division of Mycobacterial Research, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Elaine O Davis
- Division of Mycobacterial Research, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| |
Collapse
|
26
|
Focks A, Klasmeier J, Matthies M. Mechanistic link between uptake of sulfonamides and bacteriostatic effect: model development and application to experimental data from two soil microorganisms. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2010; 29:1445-1452. [PMID: 20821592 DOI: 10.1002/etc.172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Sulfonamides (SA) are antibiotic compounds that are widely used as human and veterinary pharmaceuticals. They are not rapidly biodegradable and have been detected in various environmental compartments. Effects of sulfonamides on microbial endpoints in soil have been reported from laboratory incubation studies. Sulfonamides inhibit the growth of sensitive microorganisms by competitive binding to the dihydropteroate-synthase (DHPS) enzyme of folic acid production. A mathematical model was developed that relates the extracellular SA concentration to the inhibition of the relative bacterial growth rate. Two factors--the anionic accumulation factor (AAF) and the cellular affinity factor (CAF)--determine the effective concentration of an SA. The AAF describes the SA uptake into bacterial cells and varies with both the extra- and intracellular pH values and with the acidic pKa value of an SA. The CAF subsumes relevant cellular and enzyme properties, and is directly proportional to the DHPS affinity constant for an SA. Based on the model, a mechanistic dose-response relationship is developed and evaluated against previously published data, where differences in the responses of Pseudomonas aeruginosa and Panthoea agglomerans toward changing medium pH values were found, most likely as a result of their diverse pH regulation. The derived dose-response relationship explains the pH and pKa dependency of mean effective concentration values (EC50) of eight SA and two soil bacteria based on AAF and CAF values. The mathematical model can be used to extrapolate sulfonamide effects to other pH values and to calculate the CAF as a pH-independent measure for the SA effects on microbial growth.
Collapse
Affiliation(s)
- Andreas Focks
- University of Osnabrück, Institute of Environmental Systems Research, Barbarastrasse 12, 49069 Osnabrück, Germany.
| | | | | |
Collapse
|
27
|
Probing the roles of non-homologous insertions in the N-terminal domain of Plasmodium falciparum hydroxymethylpterin pyrophosphokinase–dihydropteroate synthase. Mol Biochem Parasitol 2009; 168:135-42. [DOI: 10.1016/j.molbiopara.2009.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 06/29/2009] [Accepted: 07/09/2009] [Indexed: 11/19/2022]
|
28
|
Mathys V, Wintjens R, Lefevre P, Bertout J, Singhal A, Kiass M, Kurepina N, Wang XM, Mathema B, Baulard A, Kreiswirth BN, Bifani P. Molecular genetics of para-aminosalicylic acid resistance in clinical isolates and spontaneous mutants of Mycobacterium tuberculosis. Antimicrob Agents Chemother 2009; 53:2100-9. [PMID: 19237648 PMCID: PMC2681553 DOI: 10.1128/aac.01197-08] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 10/16/2008] [Accepted: 02/12/2009] [Indexed: 11/20/2022] Open
Abstract
The emergence of Mycobacterium tuberculosis resistant to first-line antibiotics has renewed interest in second-line antitubercular agents. Here, we aimed to extend our understanding of the mechanisms underlying para-aminosalicylic acid (PAS) resistance by analysis of six genes of the folate metabolic pathway and biosynthesis of thymine nucleotides (thyA, dfrA, folC, folP1, folP2, and thyX) and three N-acetyltransferase genes [nhoA, aac(1), and aac(2)] among PAS-resistant clinical isolates and spontaneous mutants. Mutations in thyA were identified in only 37% of the clinical isolates and spontaneous mutants. Overall, 24 distinct mutations were identified in the thyA gene and 3 in the dfrA coding region. Based on structural bioinformatics techniques, the altered ThyA proteins were predicted to generate an unfolded or dysfunctional polypeptide. The MIC was determined by Bactec/Alert and dilution assay. Sixty-three percent of the PAS-resistant isolates had no mutations in the nine genes considered in this study, revealing that PAS resistance in M. tuberculosis involves mechanisms or targets other than those pertaining to the biosynthesis of thymine nucleotides. The alternative mechanism(s) or pathway(s) associated with PAS resistance appears to be PAS concentration dependent, in marked contrast to thyA-mutated PAS-resistant isolates.
Collapse
Affiliation(s)
- Vanessa Mathys
- Laboratory of Molecular Pathology of Tuberculosis, Pasteur Institute, Scientific Institute of Public Health, Brussels, Belgium
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Gengenbacher M, Xu T, Niyomrattanakit P, Spraggon G, Dick T. Biochemical and structural characterization of the putative dihydropteroate synthase ortholog Rv1207 ofMycobacterium tuberculosis. FEMS Microbiol Lett 2008; 287:128-35. [DOI: 10.1111/j.1574-6968.2008.01302.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
30
|
Ashby CR, Jodlowski TZ, Sym D. Medications for Extensively Drug-Resistant Tuberculosis: Back to the Future? J Pharm Technol 2008. [DOI: 10.1177/875512250802400205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Objective: To reexamine the existing medications for the potential treatment of extensively drug-resistant tuberculosis (XDR-TB), based on susceptibility data, and to identify potential future medications from the literature. Data Sources: Relevant information was identified through a search of MEDLINE (1966–November 2007), PubMed (1955–November 2007), American Search Premier (1975–November 2007), International Pharmaceutical Abstracts (1960–November 2007), Science Citation Index Expanded (1996–November 2007), Cochrane Databases (publications archived until November 2007), and various tertiary sources as listed in the references, using the terms extensively drug-resistant tuberculosis (XDR-TB), ethambutol, pyrazinamide, para-aminosalicylic acid, cycloserine, linezolid, diarylquinoline, nitroimidazopyran, fluoroquinolones, β-lactams, new treatments, and ethionamide alone or in combination regimens. Study Selection and Data Extraction: After identification of the relevant information, the data presented in this article were selected based on clinical relevance and value of information. Data Synthesis: Based on susceptibility data, pyrazinamide, ethambutol, para-aminosalicylic acid, cycloserine, and ethionamide may be used for the treatment of tuberculosis. However, due to the emergence of XDR-TB, many of these agents are no longer successful treatment regimens. We have found limited data supporting potential future use of β-lactams, clarithromycin, and linezolid in resistant TB infections. TMC207, nitroimidazopyran, and SQ109 compounds may also prove to be viable options in the near future for treatment of tuberculosis, especially in cases with resistance to mainstay medications. Conclusions: Extensively resistant tuberculosis appears to be a potentially catastrophic disease if allowed to spread. Due to its resistance profile, very few potentially effective agents are available, calling attention to this growing problem.
Collapse
Affiliation(s)
- Charles R Ashby
- CHARLES R ASHBY JR PhD, Professor, St. John's University College of Pharmacy and Allied Health Professions, Queens, NY
| | - Tomasz Z Jodlowski
- TOMASZ Z JODLOWSKI PharmD BCPS, Assistant Clinical Professor, St. John's University College of Pharmacy and Allied Health Professions, Queens, NY; Infectious Diseases Clinical Pharmacist, Beth Israel Medical Center, New York, NY
| | - Donna Sym
- DONNA SYM BS PharmD, Assistant Clinical Professor, St. John's University College of Pharmacy and Allied Health Professions; Clinical Preceptor, North Shore University Hospital, Manhasset, NY
| |
Collapse
|
31
|
|
32
|
Drugs versus bugs: in pursuit of the persistent predator Mycobacterium tuberculosis. Nat Rev Microbiol 2008; 6:41-52. [PMID: 18079742 DOI: 10.1038/nrmicro1816] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Tuberculosis (TB) claims a life every 10 seconds and global mortality rates are increasing despite the use of chemotherapy. But why have we not progressed towards the eradication of the disease? There is no simple answer, although apathy, politics, poverty and our inability to fight the chronic infection have all contributed. Drug resistance and HIV-1 are also greatly influencing the current TB battle plans, as our understanding of their complicity grows. In this Review, recent efforts to fight TB will be described, specifically focusing on how drug discovery could combat the resistance and persistence that make TB worthy of the moniker 'The Great White Plague'.
Collapse
|
33
|
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]
|
34
|
Valderas MW, Bourne PC, Barrow WW. Genetic basis for sulfonamide resistance in Bacillus anthracis. Microb Drug Resist 2007; 13:11-20. [PMID: 17536929 DOI: 10.1089/mdr.2006.9992] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Natural resistance of field strains of Bacillus anthracis to drugs from the sulfonamide class of antimicrobials that act by inhibiting dihydropteroate synthase (DHPS) has been reported. Though the structure of B. anthracis DHPS has been determined, its connection to the apparent intrinsic sulfonamide resistance of the bacterium has not been established. The aim of this study was to determine if a connection exists between DHPS and the observed sulfonamide resistance of B. anthracis. Microdilution broth assays verified that B. anthracis Sterne is highly resistant to a variety of sulfonamides with minimum inhibitory concentrations (MICs) exceeding 1250 microg/ml. A putative gene encoding DHPS (folP) was amplified from B. anthracis Sterne chromosomal DNA by polymerase chain reaction (PCR) and cloned. Sequence comparisons showed 100% identity with DHPSs from published genome sequences for various strains of B. anthracis. Additionally, expression of folP in B. anthracis Sterne was confirmed. Functionality of the B. anthracis DHPS was confirmed by complementation of an Escherichia coli folP deletion mutant as well as a standard enzyme assay. Concomitant transfer of high level sulfonamide resistance to this mutant along with increased sulfonamide IC(50)values for purified B. anthracis DHPS links DHPS to sulfonamide resistance in B. anthracis. These findings lay the groundwork that will aid future development of antimicrobics that target DHPS to treat anthrax infections.
Collapse
Affiliation(s)
- Michelle Wright Valderas
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | | | | |
Collapse
|
35
|
Fernley RT, Iliades P, Macreadie I. A rapid assay for dihydropteroate synthase activity suitable for identification of inhibitors. Anal Biochem 2006; 360:227-34. [PMID: 17134675 DOI: 10.1016/j.ab.2006.10.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 09/27/2006] [Accepted: 10/24/2006] [Indexed: 11/25/2022]
Abstract
The enzymes 6-hydroxymethylpterin pyrophosphokinase (HPPK) and dihydropteroate synthase (DHPS) catalyze sequential steps in folate biosynthesis. They are present in microorganisms but absent in mammals and therefore are especially suitable targets for antimicrobials. Sulfa drugs (sulfonamides and sulfones) currently are used as antimicrobials targeting DHPS, although resistance to these drugs is increasing. The most widely used assay that measures activity of these enzymes, to assess new inhibitors in vitro, is not amenable to automation. This article describes a simple, coupled, enzymatic spectrophotometric assay where the product of the DHPS reaction, dihydropteroate, is reduced to tetrahydropteroate by excess dihydrofolate reductase (DHFR) using the cofactor NADPH. The oxidation of NADPH is monitored at 340 nm. The activity of both HPPK and DHPS can be measured in this assay, and it has been used to measure kinetic parameters of wild-type and sulfa drug-resistant DHPS enzymes to demonstrate the utility of the assay. It is a sensitive and reproducible assay that can be readily automated and used in multiwell plates. This NADPH-coupled microplate photometric assay could be used for rapid screening of chemical libraries for novel inhibitors of folate biosynthesis as the first step in developing new antimicrobial drugs targeting the folate biosynthetic pathway.
Collapse
Affiliation(s)
- Ross T Fernley
- CSIRO, Molecular and Health Technologies, Parkville, Vic. 3052, Australia.
| | | | | |
Collapse
|
36
|
Cambau E, Carthagena L, Chauffour A, Ji B, Jarlier V. Dihydropteroate synthase mutations in the folP1 gene predict dapsone resistance in relapsed cases of leprosy. Clin Infect Dis 2005; 42:238-41. [PMID: 16355335 DOI: 10.1086/498506] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Accepted: 09/03/2005] [Indexed: 11/03/2022] Open
Abstract
Molecular detection was compared with the mouse footpad inoculation test for detection of dapsone resistance in 38 strains of Mycobacterium leprae. Mutations of the folP1 gene (at codons 53 or 55) were found in 6 of 6 strains with high-level resistance, in 3 of 4 strains with intermediate-level resistance, and in 1 of 6 strains with low-level resistance, but not in 22 dapsone-susceptible strains. In cases of infection with strains of M. leprae carrying the folP1 mutation, therapy with dapsone may be replaced by therapy with a fluoroquinolone.
Collapse
Affiliation(s)
- Emmanuelle Cambau
- Laboratoire de Bacteriologie-Hygiene, Centre National de Reference pour la Resistance des Mycobacteries aux Antituberculeux, Faculte de Medecine Pitie-Salpetriere, Universite Paris, Paris, France
| | | | | | | | | |
Collapse
|
37
|
Berglez J, Pilling P, Macreadie I, Fernley RT. Purification, properties, and crystallization of Saccharomyces cerevisiae dihydropterin pyrophosphokinase-dihydropteroate synthase. Protein Expr Purif 2005; 41:355-62. [PMID: 15866722 DOI: 10.1016/j.pep.2005.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 02/02/2005] [Indexed: 11/29/2022]
Abstract
The tri-functional enzyme of Saccharomyces cerevisiae dihydroneopterin aldolase (DHNA)-dihydropterin pyrophosphokinase (PPPK)-dihydropteroate synthase (DHPS) catalyzes three sequential steps in folate biosynthesis. A cDNA encoding the PPPK and DHPS domains of the tri-functional enzyme has been cloned. This bi-functional enzyme was expressed as a His(6) fusion protein in Escherichia coli and the protein was purified to apparent homogeneity. The purified protein possesses both PPPK and DHPS activities as measured by the incorporation of [(3)H]p-ABA into the appropriate substrate. The pH optimum of the DHPS activity was determined to be 8.5. Gel filtration measurement indicates that the protein exists as a dimer in solution. A robotic screening method was used to identify crystallization conditions. Bi-pyramidal crystals of the enzyme formed with the protein in the presence of a pterin substrate analog in phosphate buffer (pH 6.3) and these diffracted to 2.3A. Structural information from these crystals could be used to design novel drugs to inhibit folate biosynthesis.
Collapse
|
38
|
Kasekarn W, Sirawaraporn R, Chahomchuen T, Cowman AF, Sirawaraporn W. Molecular characterization of bifunctional hydroxymethyldihydropterin pyrophosphokinase-dihydropteroate synthase from Plasmodium falciparum. Mol Biochem Parasitol 2005; 137:43-53. [PMID: 15279950 DOI: 10.1016/j.molbiopara.2004.04.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2003] [Revised: 04/01/2004] [Accepted: 04/09/2004] [Indexed: 11/20/2022]
Abstract
A 2118-base pair gene encoding the bifunctional hydroxymethyldihydropterin pyrophosphokinase-dihydropteroate syntheses of Plasmodium falciparum (pfPPPK-DHPS) was expressed under the control of the T5 promoter in a DHPS-deficient Escherichia coli strain. The enzyme was purified to near homogeneity using nickel affinity chromatography followed by gel filtration and migrates as an intense band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with apparent mass of approximately 83 kDa. Gel filtration suggested that the native pfPPPK-DHPS might exist as a tetramer of identical subunits. The enzyme was found to be Mg2+ - and ATP-dependent and had optimal temperature ranging from 37 to 45 degrees C with peak activity at pH 10. Sodium chloride and potassium chloride at 0.2 and 0.4 M, respectively, activated the activity of the enzyme but higher salt concentrations were inhibitory. Guanidine-HCl and urea inhibited the enzyme activity by 50% at 0.25 and 0.9 M, respectively. Kinetic properties of the recombinant pfPPPK-DHPS were investigated. Sulfathiazole and dapsone were potent inhibitors of pfPPPK-DHPS, whilst sulfadoxine, sulfanilamide, sulfacetamide and p-aminosalicylic acid were less inhibitory. Our construct provides an abundant source of recombinant pfPPPK-DHPS for crystallization and drug screening.
Collapse
Affiliation(s)
- Waraporn Kasekarn
- Department of Biochemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
| | | | | | | | | |
Collapse
|
39
|
Iliades P, Meshnick SR, Macreadie IG. Dihydropteroate synthase mutations in Pneumocystis jiroveci can affect sulfamethoxazole resistance in a Saccharomyces cerevisiae model. Antimicrob Agents Chemother 2004; 48:2617-23. [PMID: 15215118 PMCID: PMC434176 DOI: 10.1128/aac.48.7.2617-2623.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dihydropteroate synthase (DHPS) mutations in Pneumocystis jiroveci have been associated epidemiologically with resistance to sulfamethoxazole (SMX). Since P. jiroveci cannot be cultured, inherent drug resistance cannot be measured. This study explores the effects of these mutations in a tractable model organism, Saccharomyces cerevisiae. Based on the sequence conservation between the DHPS enzymes of P. jiroveci and S. cerevisiae, together with the structural conservation of the three known DHPS structures, DHPS substitutions commonly observed in P. jiroveci were reverse engineered into the S. cerevisiae DHPS. Those mutations, T(597)A and P(599)S, can occur singly but are most commonly found together and are associated with SMX treatment failure. Mutations encoding the corresponding changes in the S. cerevisiae dhps were made in a yeast centromere vector, p414FYC, which encodes the native yeast DHPS as part of a trifunctional protein that also includes the two enzymes upstream of DHPS in the folic acid synthesis pathway, dihydroneopterin aldolase and 2-amino-4-hydroxymethyl dihydropteridine pyrophosphokinase. A yeast strain with dhps deleted was employed as the host strain, and transformants having DHPS activity were recovered. Mutants having both T(597) and P(599) substitutions had a requirement for p-aminobenzoic acid (PABA), consistent with resistance being associated with altered substrate binding. These mutants could be adapted for growth in the absence of PABA, which coincided with increased sulfa drug resistance. Upregulated PABA synthesis was thus implicated as a mechanism for sulfa drug resistance for mutants having two DHPS substitutions.
Collapse
Affiliation(s)
- Peter Iliades
- CSIRO Health Sciences and Nutrition, 343 Royal Parade, Parkville, Victoria 3052, Australia.
| | | | | |
Collapse
|
40
|
Berglez J, Iliades P, Sirawaraporn W, Coloe P, Macreadie I. Analysis in Escherichia coli of Plasmodium falciparum dihydropteroate synthase (DHPS) alleles implicated in resistance to sulfadoxine. Int J Parasitol 2004; 34:95-100. [PMID: 14711594 DOI: 10.1016/j.ijpara.2003.09.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Mutations in Plasmodium falciparum dihydropteroate synthase have been linked to resistance to the antimalarial drug, sulfadoxine, which competes with the dihydropteroate synthase substrate, p-aminobenzoate. In an effort to evaluate the role of these mutations in a simple model system, we have expressed six relevant alleles of the P. falciparum dihydropteroate synthase gene in Escherichia coli. When each construct was produced in a dihydropteroate synthase disrupted E. coli strain that required thymidine, the thymidine requirement was lost, indicating heterologous complementation had occurred. In the presence of sulfadoxine, the growth of the strain with the wild-type dihydropteroate synthase allele was inhibited while those containing each of the five mutant alleles grew, indicating that these mutations can confer sulfadoxine resistance in E. coli. When tested against twelve additional 'sulfa' drugs a variety of responses were obtained. All strains were resistant to sulfadiazine, but the wild-type allele conferred sensitivity to all other sulfa drugs. Three alleles conferred resistance to dapsone, a drug that is to be targetted for a new regime of malaria treatment in Africa. All mutant alleles remained sensitive to sulfachloropyridazine and sulfacetamide. These results suggest new drugs that could be tried for effective malaria treatment.
Collapse
Affiliation(s)
- Janette Berglez
- Biomolecular Research Institute, CSIRO Health Sciences and Nutrition, 343 Royal Parade, Parkville, Vic. 3052, Australia
| | | | | | | | | |
Collapse
|
41
|
Rengarajan J, Sassetti CM, Naroditskaya V, Sloutsky A, Bloom BR, Rubin EJ. The folate pathway is a target for resistance to the drug para-aminosalicylic acid (PAS) in mycobacteria. Mol Microbiol 2004; 53:275-82. [PMID: 15225321 DOI: 10.1111/j.1365-2958.2004.04120.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The increasing rate of multidrug-resistant tuberculosis has led to more use of second-line antibiotics such as para-aminosalicylic acid (PAS). The mode of action of PAS remains unclear, and mechanisms of resistance to this drug are undefined. We have isolated PAS-resistant transposon mutants of Mycobacterium bovis BCG with insertions in the thymidylate synthase (thyA) gene, a critical determinant of intracellular folate levels. BCG thyA mutants have reduced thymidylate synthase activity and are resistant to known inhibitors of the folate pathway. We also find that mutations in thyA are associated with clinical PAS resistance. We have identified PAS-resistant Mycobacterium tuberculosis isolates from infected patients, which harbour mutations in thyA and show reduced activity of the encoded enzyme. Thus, PAS acts in the folate pathway, and thyA mutations probably represent a mechanism of developing resistance not only to PAS but also to other drugs that target folate metabolism.
Collapse
Affiliation(s)
- Jyothi Rengarajan
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | | | | | | | | | | |
Collapse
|
42
|
Abstract
The term 'microbial persistence' describes a phenomenon whereby microorganisms which are drug-susceptible when tested outside the body are nevertheless capable of surviving within the body despite intensive therapy with the appropriate antimicrobial drug. In clinical practice this phenomenon obviously has to do with the post-treatment 'carrier state' and with post-treatment relapse. In short, it is this phenomenon which is responsible for our inability to eradicate an infection from a person or a community by the use of drugs. - Walsh McDermott, The Yale Journal of Biology and Medicine 30, 257 (1958).
Collapse
Affiliation(s)
- J D McKinney
- The Rockefeller University, Laboratory of Infection Biology, New York, NY 10021, USA.
| |
Collapse
|
43
|
Baca AM, Sirawaraporn R, Turley S, Sirawaraporn W, Hol WG. Crystal structure of Mycobacterium tuberculosis 7,8-dihydropteroate synthase in complex with pterin monophosphate: new insight into the enzymatic mechanism and sulfa-drug action. J Mol Biol 2000; 302:1193-212. [PMID: 11007651 DOI: 10.1006/jmbi.2000.4094] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The enzyme 7,8-dihydropteroate synthase (DHPS) catalyzes the condensation of para-aminobenzoic acid (pABA) with 6-hydroxymethyl-7, 8-dihydropterin-pyrophosphate to form 7,8-dihydropteroate and pyrophosphate. DHPS is essential for the de novo synthesis of folate in prokaryotes, lower eukaryotes, and in plants, but is absent in mammals. Inhibition of this enzyme's activity by sulfonamide and sulfone drugs depletes the folate pool, resulting in growth inhibition and cell death. Here, we report the 1.7 A resolution crystal structure of the binary complex of 6-hydroxymethylpterin monophosphate (PtP) with DHPS from Mycobacterium tuberculosis (Mtb), a pathogen responsible for the death of millions of human beings each year. Comparison to other DHPS structures reveals that the M. tuberculosis DHPS structure is in a unique conformation in which loop 1 closes over the active site. The Mtb DHPS structure hints at a mechanism in which both loops 1 and 2 play important roles in catalysis by shielding the active site from bulk solvent and allowing pyrophosphoryl transfer to occur. A binding mode for pABA, sulfonamides and sulfones is suggested based on: (i) the new conformation of the closed loop 1; (ii) the distribution of dapsone and sulfonamide resistance mutations; (iii) the observed direction of the bond between the 6-methyl carbon atom and the bridging oxygen atom to the alpha-phosphate group in the Mtb DHPS:PtP binary complex; and (iv) the conformation of loop 2 in the Escherichia coli DHPS structure. Finally, the Mtb DHPS structure reveals a highly conserved pterin binding pocket that may be exploited for the design of novel antimycobacterial agents.
Collapse
Affiliation(s)
- A M Baca
- Department of Bioengineering and Biomolecular Structure Center, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | |
Collapse
|