1
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Schinazi RF, Patel D, Ehteshami M. The best backbone for HIV prevention, treatment, and elimination: Emtricitabine+tenofovir. Antivir Ther 2022; 27:13596535211067599. [PMID: 35491570 DOI: 10.1177/13596535211067599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The advent of antiretroviral combination therapy has significantly impacted the HIV/AIDS epidemic. No longer a death sentence, HIV infection can be controlled and suppressed using cocktail therapies that contain two or more small molecule drugs. This review aims to highlight the discovery, development, and impact of one such molecule, namely, emtricitabine (FTC, emtriva), which is one of the most successful drugs in the fight against HIV/AIDS and has been taken by over 94% of individuals infected with HIV in the USA. We also pay tribute to Dr. John C. Martin, former CEO and Chairman of Gilead Sciences, who unexpectedly passed away in 2021. A true visionary, he was instrumental in delivering FTC, as part of combination therapy with TDF (tenofovir, viread) to the global stage. As the fight to eradicate HIV marches on, we honor Dr. Martin's legacy of collaboration, achievement, and hope.
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Affiliation(s)
- Raymond F Schinazi
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, 1371Emory University School of Medicine and Children Healthcare of Atlanta, Atlanta, GA, USA
| | - Dharmeshkumar Patel
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, 1371Emory University School of Medicine and Children Healthcare of Atlanta, Atlanta, GA, USA
| | - Maryam Ehteshami
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, 1371Emory University School of Medicine and Children Healthcare of Atlanta, Atlanta, GA, USA
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2
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Sluis-Cremer N. Retroviral reverse transcriptase: Structure, function and inhibition. Enzymes 2021; 50:179-194. [PMID: 34861936 DOI: 10.1016/bs.enz.2021.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Reverse transcriptase (RT) is a multifunctional enzyme that has RNA- and DNA-dependent DNA polymerase activity and ribonuclease H (RNase H) activity, and is responsible for the reverse transcription of retroviral single-stranded RNA into double-stranded DNA. The essential role that RT plays in the human immunodeficiency virus (HIV) life cycle is highlighted by the fact that multiple antiviral drugs-which can be classified into two distinct therapeutic classes-are routinely used to treat and/or prevent HIV infection. This book chapter provides detailed insights into the three-dimensional structure of HIV RT, the biochemical mechanisms of DNA polymerization and RNase H activity, and the mechanisms by which nucleoside/nucleotide and nonnucleoside RT inhibitors block reverse transcription.
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Affiliation(s)
- Nicolas Sluis-Cremer
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
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3
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Cilento ME, Kirby KA, Sarafianos SG. Avoiding Drug Resistance in HIV Reverse Transcriptase. Chem Rev 2021; 121:3271-3296. [PMID: 33507067 DOI: 10.1021/acs.chemrev.0c00967] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
HIV reverse transcriptase (RT) is an enzyme that plays a major role in the replication cycle of HIV and has been a key target of anti-HIV drug development efforts. Because of the high genetic diversity of the virus, mutations in RT can impart resistance to various RT inhibitors. As the prevalence of drug resistance mutations is on the rise, it is necessary to design strategies that will lead to drugs less susceptible to resistance. Here we provide an in-depth review of HIV reverse transcriptase, current RT inhibitors, novel RT inhibitors, and mechanisms of drug resistance. We also present novel strategies that can be useful to overcome RT's ability to escape therapies through drug resistance. While resistance may not be completely avoidable, designing drugs based on the strategies and principles discussed in this review could decrease the prevalence of drug resistance.
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Affiliation(s)
- Maria E Cilento
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, United States.,Children's Healthcare of Atlanta, Atlanta, Georgia 30307, United States
| | - Karen A Kirby
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, United States.,Children's Healthcare of Atlanta, Atlanta, Georgia 30307, United States
| | - Stefan G Sarafianos
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, United States.,Children's Healthcare of Atlanta, Atlanta, Georgia 30307, United States
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4
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Gong S, Kirmizialtin S, Chang A, Mayfield JE, Zhang YJ, Johnson KA. Kinetic and thermodynamic analysis defines roles for two metal ions in DNA polymerase specificity and catalysis. J Biol Chem 2020; 296:100184. [PMID: 33310704 PMCID: PMC7948414 DOI: 10.1074/jbc.ra120.016489] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/05/2020] [Accepted: 12/11/2020] [Indexed: 11/06/2022] Open
Abstract
Magnesium ions play a critical role in catalysis by many enzymes and contribute to the fidelity of DNA polymerases through a two-metal ion mechanism. However, specificity is a kinetic phenomenon and the roles of Mg2+ ions in each step in the catalysis have not been resolved. We first examined the roles of Mg2+ by kinetic analysis of single nucleotide incorporation catalyzed by HIV reverse transcriptase. We show that Mg.dNTP binding induces an enzyme conformational change at a rate that is independent of free Mg2+ concentration. Subsequently, the second Mg2+ binds to the closed state of the enzyme-DNA-Mg.dNTP complex (Kd = 3.7 mM) to facilitate catalysis. Weak binding of the catalytic Mg2+ contributes to fidelity by sampling the correctly aligned substrate without perturbing the equilibrium for nucleotide binding at physiological Mg2+ concentrations. An increase of the Mg2+ concentration from 0.25 to 10 mM increases nucleotide specificity (kcat/Km) 12-fold largely by increasing the rate of the chemistry relative to the rate of nucleotide release. Mg2+ binds very weakly (Kd ≤ 37 mM) to the open state of the enzyme. Analysis of published crystal structures showed that HIV reverse transcriptase binds only two metal ions prior to incorporation of a correct base pair. Molecular dynamics simulations support the two-metal ion mechanism and the kinetic data indicating weak binding of the catalytic Mg2+. Molecular dynamics simulations also revealed the importance of the divalent cation cloud surrounding exposed phosphates on the DNA. These results enlighten the roles of the two metal ions in the specificity of DNA polymerases.
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Affiliation(s)
- Shanzhong Gong
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Serdal Kirmizialtin
- Chemistry Program, Science Division, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Adrienne Chang
- Chemistry Program, Science Division, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Joshua E Mayfield
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Kenneth A Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA.
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5
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Post-Catalytic Complexes with Emtricitabine or Stavudine and HIV-1 Reverse Transcriptase Reveal New Mechanistic Insights for Nucleotide Incorporation and Drug Resistance. Molecules 2020; 25:molecules25204868. [PMID: 33096918 PMCID: PMC7587939 DOI: 10.3390/molecules25204868] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/17/2020] [Accepted: 10/19/2020] [Indexed: 11/17/2022] Open
Abstract
Human immunodeficiency virus 1 (HIV-1) infection is a global health issue since neither a cure nor a vaccine is available. However, the highly active antiretroviral therapy (HAART) has improved the life expectancy for patients with acquired immunodeficiency syndrome (AIDS). Nucleoside reverse transcriptase inhibitors (NRTIs) are in almost all HAART and target reverse transcriptase (RT), an essential enzyme for the virus. Even though NRTIs are highly effective, they have limitations caused by RT resistance. The main mechanisms of RT resistance to NRTIs are discrimination and excision. Understanding the molecular mechanisms for discrimination and excision are essential to develop more potent and selective NRTIs. Using protein X-ray crystallography, we determined the first crystal structure of RT in its post-catalytic state in complex with emtricitabine, (-)FTC or stavudine (d4T). Our structural studies provide the framework for understanding how RT discriminates between NRTIs and natural nucleotides, and for understanding the requirement of (-)FTC to undergo a conformation change for successful incorporation by RT. The crystal structure of RT in post-catalytic complex with d4T provides a "snapshot" for considering the possible mechanism of how RT develops resistance for d4T via excision. The findings reported herein will contribute to the development of next generation NRTIs.
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6
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Saepuloh U, Iskandriati D, Pamungkas J, Solihin DD, Mariya SS, Sajuthi D. Construction of A Preliminary Three-Dimensional Structure Simian betaretrovirus Serotype-2 (SRV-2) Reverse Transcriptase Isolated from Indonesian Cynomolgus Monkey. Trop Life Sci Res 2020; 31:47-61. [PMID: 33214855 PMCID: PMC7652245 DOI: 10.21315/tlsr2020.31.3.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Simian betaretrovirus serotype-2 (SRV-2) is an important pathogenic agent in Asian macaques. It is a potential confounding variable in biomedical research. SRV-2 also provides a valuable viral model compared to other retroviruses which can be used for understanding many aspects of retroviral-host interactions and immunosuppression, infection mechanism, retroviral structure, antiretroviral and vaccine development. In this study, we isolated the gene encoding reverse transcriptase enzyme (RT) of SRV-2 that infected Indonesian cynomolgus monkey (Mf ET1006) and predicted the three dimensional structure model using the iterative threading assembly refinement (I-TASSER) computational programme. This SRV-2 RT Mf ET1006 consisted of 547 amino acids at nucleotide position 3284–4925 of whole genome SRV-2. The polymerase active site located in the finger/palm subdomain characterised by three conserved catalytic aspartates (Asp90, Asp165, Asp166), and has a highly conserved YMDD motif as Tyr163, Met164, Asp165 and Asp166. We estimated that this SRV-2 RT Mf ET1006 structure has the accuracy of template modelling score (TM-score 0.90 ± 0.06) and root mean square deviation (RMSD) 4.7 ± 3.1Å, indicating that this model can be trusted and the accuracy can be seen from the appearance of protein folding in tertiary structure. The superpositionings between SRV-2 RT Mf ET1006 and Human Immunodeficiency Virus-1 (HIV-1) RT were performed to predict the structural in details and to optimise the best fits for illustrations. This SRV-2 RT Mf ET1006 structure model has the highest homology to HIV-1 RT (2B6A.pdb) with estimated accuracy at TM-score 0.911, RMSD 1.85 Å, and coverage of 0.953. This preliminary study of SRV-2 RT Mf ET1006 structure modelling is intriguing and provide some information to explore the molecular characteristic and biochemical mechanism of this enzyme.
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Affiliation(s)
- Uus Saepuloh
- Primate Research Centre, Bogor Agricultural University (PSSP LPPM IPB), Jalan Lodaya II/5 Bogor 16151, Indonesia
| | - Diah Iskandriati
- Primate Research Centre, Bogor Agricultural University (PSSP LPPM IPB), Jalan Lodaya II/5 Bogor 16151, Indonesia
| | - Joko Pamungkas
- Primate Research Centre, Bogor Agricultural University (PSSP LPPM IPB), Jalan Lodaya II/5 Bogor 16151, Indonesia.,Faculty of Veterinary Medicine, Bogor Agricultural University, Kampus Darmaga, Bogor 16680, Indonesia
| | - Dedy Duryadi Solihin
- Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Kampus Darmaga, Bogor 16680, Indonesia
| | - Sela Septima Mariya
- Primate Research Centre, Bogor Agricultural University (PSSP LPPM IPB), Jalan Lodaya II/5 Bogor 16151, Indonesia
| | - Dondin Sajuthi
- Primate Research Centre, Bogor Agricultural University (PSSP LPPM IPB), Jalan Lodaya II/5 Bogor 16151, Indonesia.,Faculty of Veterinary Medicine, Bogor Agricultural University, Kampus Darmaga, Bogor 16680, Indonesia
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7
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Melo R, Lemos A, Preto AJ, Bueschbell B, Matos-Filipe P, Barreto C, Almeida JG, Silva RDM, Correia JDG, Moreira IS. An Overview of Antiretroviral Agents for Treating HIV Infection in Paediatric Population. Curr Med Chem 2020; 27:760-794. [PMID: 30182840 DOI: 10.2174/0929867325666180904123549] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 07/11/2018] [Accepted: 07/11/2018] [Indexed: 12/19/2022]
Abstract
Paediatric Acquired ImmunoDeficiency Syndrome (AIDS) is a life-threatening and infectious disease in which the Human Immunodeficiency Virus (HIV) is mainly transmitted through Mother-To- Child Transmission (MTCT) during pregnancy, labour and delivery, or breastfeeding. This review provides an overview of the distinct therapeutic alternatives to abolish the systemic viral replication in paediatric HIV-1 infection. Numerous classes of antiretroviral agents have emerged as therapeutic tools for downregulation of different steps in the HIV replication process. These classes encompass Non- Nucleoside Analogue Reverse Transcriptase Inhibitors (NNRTIs), Nucleoside/Nucleotide Analogue Reverse Transcriptase Inhibitors (NRTIs/NtRTIs), INtegrase Inhibitors (INIs), Protease Inhibitors (PIs), and Entry Inhibitors (EIs). Co-administration of certain antiretroviral drugs with Pharmacokinetic Enhancers (PEs) may boost the effectiveness of the primary therapeutic agent. The combination of multiple antiretroviral drug regimens (Highly Active AntiRetroviral Therapy - HAART) is currently the standard therapeutic approach for HIV infection. So far, the use of HAART offers the best opportunity for prolonged and maximal viral suppression, and preservation of the immune system upon HIV infection. Still, the frequent administration of high doses of multiple drugs, their inefficient ability to reach the viral reservoirs in adequate doses, the development of drug resistance, and the lack of patient compliance compromise the complete HIV elimination. The development of nanotechnology-based drug delivery systems may enable targeted delivery of antiretroviral agents to inaccessible viral reservoir sites at therapeutic concentrations. In addition, the application of Computer-Aided Drug Design (CADD) approaches has provided valuable tools for the development of anti-HIV drug candidates with favourable pharmacodynamics and pharmacokinetic properties.
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Affiliation(s)
- Rita Melo
- Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), Bobadela LRS 2695-066, Portugal.,CNC - Center for Neuroscience and Cell Biology; Rua Larga, FMUC, Polo I, 1ºandar, Universidade de Coimbra, Coimbra 3004-517, Portugal
| | - Agostinho Lemos
- CNC - Center for Neuroscience and Cell Biology; Rua Larga, FMUC, Polo I, 1ºandar, Universidade de Coimbra, Coimbra 3004-517, Portugal.,GIGA Cyclotron Research Centre In Vivo Imaging, University of Liège, Liège 4000, Belgium
| | - António J Preto
- CNC - Center for Neuroscience and Cell Biology; Rua Larga, FMUC, Polo I, 1ºandar, Universidade de Coimbra, Coimbra 3004-517, Portugal
| | - Beatriz Bueschbell
- Pharmaceutical Chemistry I, PharmaCenter, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Pedro Matos-Filipe
- CNC - Center for Neuroscience and Cell Biology; Rua Larga, FMUC, Polo I, 1ºandar, Universidade de Coimbra, Coimbra 3004-517, Portugal
| | - Carlos Barreto
- CNC - Center for Neuroscience and Cell Biology; Rua Larga, FMUC, Polo I, 1ºandar, Universidade de Coimbra, Coimbra 3004-517, Portugal
| | - José G Almeida
- CNC - Center for Neuroscience and Cell Biology; Rua Larga, FMUC, Polo I, 1ºandar, Universidade de Coimbra, Coimbra 3004-517, Portugal
| | - Rúben D M Silva
- Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), Bobadela LRS 2695-066, Portugal
| | - João D G Correia
- Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), Bobadela LRS 2695-066, Portugal
| | - Irina S Moreira
- CNC - Center for Neuroscience and Cell Biology; Rua Larga, FMUC, Polo I, 1ºandar, Universidade de Coimbra, Coimbra 3004-517, Portugal.,Bijvoet Center for Biomolecular Research, Faculty of Science - Chemistry, Utrecht University, Utrecht 3584CH, Netherland
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8
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Structural features in common of HBV and HIV-1 resistance against chirally-distinct nucleoside analogues entecavir and lamivudine. Sci Rep 2020; 10:3021. [PMID: 32080249 PMCID: PMC7033138 DOI: 10.1038/s41598-020-59775-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 02/04/2020] [Indexed: 12/17/2022] Open
Abstract
Chronic hepatitis B virus (HBV) infection is a major public health problem that affects millions of people worldwide. Nucleoside analogue reverse transcriptase (RT) inhibitors, such as entecavir (ETV) and lamivudine (3TC), serve as crucial anti-HBV drugs. However, structural studies of HBV RT have been hampered due to its unexpectedly poor solubility. Here, we show that human immunodeficiency virus type-1 (HIV-1) with HBV-associated amino acid substitutions Y115F/F116Y/Q151M in its RT (HIVY115F/F116Y/Q151M) is highly susceptible to ETV and 3TC. Additionally, we experimentally simulated previously reported ETV/3TC resistance for HBV using HIVY115F/F116Y/Q151M with F160M/M184V (L180M/M204V in HBV RT) substituted. We determined crystal structures for HIV-1 RTY115F/F116Y/Q151M:DNA complexed with 3TC-triphosphate (3TC-TP)/ETV-triphosphate (ETV-TP)/dCTP/dGTP. These structures revealed an atypically tight binding conformation of 3TC-TP, where the Met184 side-chain is pushed away by the oxathiolane of 3TC-TP and exocyclic methylene of ETV-TP. Structural analysis of RTY115F/F116Y/Q151M/F160M/M184V:DNA:3TC-TP also demonstrated that the loosely bound 3TC-TP is misaligned at the active site to prevent a steric clash with the side chain γ-methyl of Val184. These findings shed light on the common structural mechanism of HBV and HIV-1 resistance to 3TC and ETV and should aid in the design of new agents to overcome drug resistance to 3TC and ETV.
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9
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Bertoletti N, Chan AH, Schinazi RF, Yin YW, Anderson KS. Structural insights into the recognition of nucleoside reverse transcriptase inhibitors by HIV-1 reverse transcriptase: First crystal structures with reverse transcriptase and the active triphosphate forms of lamivudine and emtricitabine. Protein Sci 2019; 28:1664-1675. [PMID: 31301259 PMCID: PMC6699100 DOI: 10.1002/pro.3681] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/03/2019] [Accepted: 07/08/2019] [Indexed: 12/27/2022]
Abstract
The retrovirus HIV-1 has been a major health issue since its discovery in the early 80s. In 2017, over 37 million people were infected with HIV-1, of which 1.8 million were new infections that year. Currently, the most successful treatment regimen is the highly active antiretroviral therapy (HAART), which consists of a combination of three to four of the current 26 FDA-approved HIV-1 drugs. Half of these drugs target the reverse transcriptase (RT) enzyme that is essential for viral replication. One class of RT inhibitors is nucleoside reverse transcriptase inhibitors (NRTIs), a crucial component of the HAART. Once incorporated into DNA, NRTIs function as a chain terminator to stop viral DNA replication. Unfortunately, treatment with NRTIs is sometimes linked to toxicity caused by off-target side effects. NRTIs may also target the replicative human mitochondrial DNA polymerase (Pol γ), causing long-term severe drug toxicity. The goal of this work is to understand the discrimination mechanism of different NRTI analogues by RT. Crystal structures and kinetic experiments are essential for the rational design of new molecules that are able to bind selectively to RT and not Pol γ. Structural comparison of NRTI-binding modes with both RT and Pol γ enzymes highlights key amino acids that are responsible for the difference in affinity of these drugs to their targets. Therefore, the long-term goal of this research is to develop safer, next generation therapeutics that can overcome off-target toxicity.
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Affiliation(s)
- Nicole Bertoletti
- Department of PharmacologyYale University School of MedicineNew HavenConnecticut
| | - Albert H. Chan
- Department of PharmacologyYale University School of MedicineNew HavenConnecticut
| | - Raymond F. Schinazi
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Center for AIDS ResearchEmory University School of MedicineAtlantaGeorgia
| | - Y. Whitney Yin
- Department of Pharmacology and ToxicologyUniversity of Texas Medical BranchGalvestonTexas
- Sealy Center for Structural BiologyUniversity of Texas Medical BranchGalvestonTexas
| | - Karen S. Anderson
- Department of PharmacologyYale University School of MedicineNew HavenConnecticut
- Department of Molecular Biophysics and BiochemistryYale University School of MedicineNew HavenConnecticut
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10
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Agnello S, Brand M, Chellat MF, Gazzola S, Riedl R. A Structural View on Medicinal Chemistry Strategies against Drug Resistance. Angew Chem Int Ed Engl 2019; 58:3300-3345. [PMID: 29846032 DOI: 10.1002/anie.201802416] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/24/2018] [Indexed: 12/31/2022]
Abstract
The natural phenomenon of drug resistance is a widespread issue that hampers the performance of drugs in many major clinical indications. Antibacterial and antifungal drugs are affected, as well as compounds for the treatment of cancer, viral infections, or parasitic diseases. Despite the very diverse set of biological targets and organisms involved in the development of drug resistance, the underlying molecular mechanisms have been identified to understand the emergence of resistance and to overcome this detrimental process. Detailed structural information on the root causes for drug resistance is nowadays frequently available, so next-generation drugs can be designed that are anticipated to suffer less from resistance. This knowledge-based approach is essential for fighting the inevitable occurrence of drug resistance.
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Affiliation(s)
- Stefano Agnello
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
| | - Michael Brand
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
| | - Mathieu F Chellat
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
| | - Silvia Gazzola
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
| | - Rainer Riedl
- Institute of Chemistry and Biotechnology, Center for Organic and Medicinal Chemistry, Zurich University of Applied Sciences (ZHAW), Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
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11
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Agnello S, Brand M, Chellat MF, Gazzola S, Riedl R. Eine strukturelle Evaluierung medizinalchemischer Strategien gegen Wirkstoffresistenzen. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201802416] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Stefano Agnello
- Institut für Chemie und Biotechnologie; FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
| | - Michael Brand
- Institut für Chemie und Biotechnologie; FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
| | - Mathieu F. Chellat
- Institut für Chemie und Biotechnologie; FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
| | - Silvia Gazzola
- Institut für Chemie und Biotechnologie; FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
| | - Rainer Riedl
- Institut für Chemie und Biotechnologie; FS Organische Chemie und Medizinalchemie; Zürcher Hochschule für Angewandte Wissenschaften (ZHAW); Einsiedlerstrasse 31 CH-8820 Wädenswil Schweiz
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12
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Yasutake Y, Hattori SI, Tamura N, Matsuda K, Kohgo S, Maeda K, Mitsuya H. Active-site deformation in the structure of HIV-1 RT with HBV-associated septuple amino acid substitutions rationalizes the differential susceptibility of HIV-1 and HBV against 4'-modified nucleoside RT inhibitors. Biochem Biophys Res Commun 2019; 509:943-948. [PMID: 30648556 DOI: 10.1016/j.bbrc.2019.01.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 01/05/2019] [Indexed: 12/29/2022]
Abstract
Nucleoside analogue reverse transcriptase (RT) inhibitors (NRTIs) are major antiviral agents against hepatitis B virus (HBV) and human immunodeficiency virus type-1 (HIV-1). However, the notorious insoluble property of HBV RT has prevented atomic-resolution structural studies and rational anti-HBV drug design. Here, we created HIV-1 RT mutants containing HBV-mimicking sextuple or septuple amino acid substitutions at the nucleoside-binding site (N-site) and verified that these mutants retained the RT activity. The most active RT mutant, HIV-1 RT7MC, carrying Q151M/G112S/D113A/Y115F/F116Y/F160L/I159L was successfully crystallized, and its three-dimensional structure was determined in complex with DNA:dGTP/entecavir-triphosphate (ETV-TP), a potent anti-HBV guanosine analogue RT inhibitor, at a resolution of 2.43 Å and 2.60 Å, respectively. The structures reveal significant positional rearrangements of the amino acid side-chains at the N-site, elucidating the mechanism underlying the differential susceptibility of HIV-1 and HBV against recently reported 4'-modified NRTIs.
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Affiliation(s)
- Yoshiaki Yasutake
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, 062-8517, Japan; Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), AIST, Sapporo, 062-8517, Japan.
| | - Shin-Ichiro Hattori
- National Center for Global Health and Medicine Research Institute (NCGM), Tokyo, 162-8655, Japan
| | - Noriko Tamura
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, 062-8517, Japan
| | - Kouki Matsuda
- National Center for Global Health and Medicine Research Institute (NCGM), Tokyo, 162-8655, Japan
| | - Satoru Kohgo
- National Center for Global Health and Medicine Research Institute (NCGM), Tokyo, 162-8655, Japan; Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, 860-0082, Japan
| | - Kenji Maeda
- National Center for Global Health and Medicine Research Institute (NCGM), Tokyo, 162-8655, Japan.
| | - Hiroaki Mitsuya
- National Center for Global Health and Medicine Research Institute (NCGM), Tokyo, 162-8655, Japan; Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA; Department of Clinical Sciences, Kumamoto University Hospital, Kumamoto, 860-8556, Japan
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13
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Malik O, Khamis H, Rudnizky S, Kaplan A. The mechano-chemistry of a monomeric reverse transcriptase. Nucleic Acids Res 2018; 45:12954-12962. [PMID: 29165701 PMCID: PMC5728418 DOI: 10.1093/nar/gkx1168] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/08/2017] [Indexed: 01/28/2023] Open
Abstract
Retroviral reverse transcriptase catalyses the synthesis of an integration-competent dsDNA molecule, using as a substrate the viral RNA. Using optical tweezers, we follow the Murine Leukemia Virus reverse transcriptase as it performs strand-displacement polymerization on a template under mechanical force. Our results indicate that reverse transcriptase functions as a Brownian ratchet, with dNTP binding as the rectifying reaction of the ratchet. We also found that reverse transcriptase is a relatively passive enzyme, able to polymerize on structured templates by exploiting their thermal breathing. Finally, our results indicate that the enzyme enters the recently characterized backtracking state from the pre-translocation complex.
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Affiliation(s)
- Omri Malik
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Hadeel Khamis
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Faculty of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Sergei Rudnizky
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ariel Kaplan
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.,Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
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14
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Kankanala J, Kirby KA, Huber AD, Casey MC, Wilson DJ, Sarafianos SG, Wang Z. Design, synthesis and biological evaluations of N-Hydroxy thienopyrimidine-2,4-diones as inhibitors of HIV reverse transcriptase-associated RNase H. Eur J Med Chem 2017; 141:149-161. [PMID: 29031062 DOI: 10.1016/j.ejmech.2017.09.054] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 09/13/2017] [Accepted: 09/25/2017] [Indexed: 11/29/2022]
Abstract
Human immunodeficiency virus (HIV) reverse transcriptase (RT) associated ribonuclease H (RNase H) is the only HIV enzymatic function not targeted by current antiviral drugs. Although various chemotypes have been reported to inhibit HIV RNase H, few have shown significant antiviral activities. We report herein the design, synthesis and biological evaluation of a novel N-hydroxy thienopyrimidine-2,3-dione chemotype (11) which potently and selectively inhibited RNase H with considerable potency against HIV-1 in cell culture. Current structure-activity-relationship (SAR) identified analogue 11d as a nanomolar inhibitor of RNase H (IC50 = 0.04 μM) with decent antiviral potency (EC50 = 7.4 μM) and no cytotoxicity (CC50 > 100 μM). In extended biochemical assays compound 11d did not inhibit RT polymerase (pol) while inhibiting integrase strand transfer (INST) with 53 fold lower potency (IC50 = 2.1 μM) than RNase H inhibition. Crystallographic and molecular modeling studies confirmed the RNase H active site binding mode.
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Affiliation(s)
- Jayakanth Kankanala
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Karen A Kirby
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Andrew D Huber
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Mary C Casey
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Daniel J Wilson
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Stefan G Sarafianos
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA; Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Zhengqiang Wang
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA.
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15
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Li A, Ziehr JL, Johnson KA. A new general method for simultaneous fitting of temperature and concentration dependence of reaction rates yields kinetic and thermodynamic parameters for HIV reverse transcriptase specificity. J Biol Chem 2017; 292:6695-6702. [PMID: 28255091 DOI: 10.1074/jbc.m116.760827] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 02/21/2017] [Indexed: 11/06/2022] Open
Abstract
Recent studies have demonstrated the dominant role of induced fit in enzyme specificity of HIV reverse transcriptase and many other enzymes. However, relevant thermodynamic parameters are lacking, and equilibrium thermodynamic methods are of no avail because the key parameters can only be determined by kinetic measurement. By modifying KinTek Explorer software, we present a new general method for globally fitting data collected over a range of substrate concentrations and temperatures and apply it to HIV reverse transcriptase. Fluorescence stopped-flow methods were used to record the kinetics of enzyme conformational changes that monitor nucleotide binding and incorporation. The nucleotide concentration dependence was measured at temperatures ranging from 5 to 37 °C, and the raw data were fit globally to derive a single set of rate constants at 37 °C and a set of activation enthalpy terms to account for the kinetics at all other temperatures. This comprehensive analysis afforded thermodynamic parameters for nucleotide binding (Kd , ΔG, ΔH, and ΔS at 37 °C) and kinetic parameters for enzyme conformational changes and chemistry (rate constants and activation enthalpy). Comparisons between wild-type enzyme and a mutant resistant to nucleoside analogs used to treat HIV infections reveal that the ground state binding is weaker and the activation enthalpy for the conformational change step is significantly larger for the mutant. Further studies to explore the structural underpinnings of the observed thermodynamics and kinetics of the conformational change step may help to design better analogs to treat HIV infections and other diseases. Our new method is generally applicable to enzyme and chemical kinetics.
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Affiliation(s)
- An Li
- From the Institute for Cell and Molecular Biology, Molecular Biosciences Department, University of Texas at Austin, Austin, Texas 78712
| | - Jessica L Ziehr
- From the Institute for Cell and Molecular Biology, Molecular Biosciences Department, University of Texas at Austin, Austin, Texas 78712
| | - Kenneth A Johnson
- From the Institute for Cell and Molecular Biology, Molecular Biosciences Department, University of Texas at Austin, Austin, Texas 78712
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16
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Menéndez-Arias L, Sebastián-Martín A, Álvarez M. Viral reverse transcriptases. Virus Res 2016; 234:153-176. [PMID: 28043823 DOI: 10.1016/j.virusres.2016.12.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 12/19/2016] [Accepted: 12/24/2016] [Indexed: 12/11/2022]
Abstract
Reverse transcriptases (RTs) play a major role in the replication of Retroviridae, Metaviridae, Pseudoviridae, Hepadnaviridae and Caulimoviridae. RTs are enzymes that are able to synthesize DNA using RNA or DNA as templates (DNA polymerase activity), and degrade RNA when forming RNA/DNA hybrids (ribonuclease H activity). In retroviruses and LTR retrotransposons (Metaviridae and Pseudoviridae), the coordinated action of both enzymatic activities converts single-stranded RNA into a double-stranded DNA that is flanked by identical sequences known as long terminal repeats (LTRs). RTs of retroviruses and LTR retrotransposons are active as monomers (e.g. murine leukemia virus RT), homodimers (e.g. Ty3 RT) or heterodimers (e.g. human immunodeficiency virus type 1 (HIV-1) RT). RTs lack proofreading activity and display high intrinsic error rates. Besides, high recombination rates observed in retroviruses are promoted by poor processivity that causes template switching, a hallmark of reverse transcription. HIV-1 RT inhibitors acting on its polymerase activity constitute the backbone of current antiretroviral therapies, although novel drugs, including ribonuclease H inhibitors, are still necessary to fight HIV infections. In Hepadnaviridae and Caulimoviridae, reverse transcription leads to the formation of nicked circular DNAs that will be converted into episomal DNA in the host cell nucleus. Structural and biochemical information on their polymerases is limited, although several drugs inhibiting HIV-1 RT are known to be effective against the human hepatitis B virus polymerase. In this review, we summarize current knowledge on reverse transcription in the five virus families and discuss available biochemical and structural information on RTs, including their biosynthesis, enzymatic activities, and potential inhibition.
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Affiliation(s)
- Luis Menéndez-Arias
- Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, c/Nicolás Cabrera, 1, Campus de Cantoblanco, 28049 Madrid, Spain.
| | - Alba Sebastián-Martín
- Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, c/Nicolás Cabrera, 1, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Mar Álvarez
- Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, c/Nicolás Cabrera, 1, Campus de Cantoblanco, 28049 Madrid, Spain
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17
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Sharaf NG, Brereton AE, Byeon IJL, Karplus PA, Gronenborn AM. NMR structure of the HIV-1 reverse transcriptase thumb subdomain. JOURNAL OF BIOMOLECULAR NMR 2016; 66:273-280. [PMID: 27858311 PMCID: PMC5218889 DOI: 10.1007/s10858-016-0077-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/09/2016] [Indexed: 06/06/2023]
Abstract
The solution NMR structure of the isolated thumb subdomain of HIV-1 reverse transcriptase (RT) has been determined. A detailed comparison of the current structure with dozens of the highest resolution crystal structures of this domain in the context of the full-length enzyme reveals that the overall structures are very similar, with only two regions exhibiting local conformational differences. The C-terminal capping pattern of the αH helix is subtly different, and the loop connecting the αI and αJ helices in the p51 chain of the full-length p51/p66 heterodimeric RT differs from our NMR structure due to unique packing interactions in mature RT. Overall, our data show that the thumb subdomain folds independently and essentially the same in isolation as in its natural structural context.
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Affiliation(s)
- Naima G Sharaf
- Department of Structural Biology and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh, School of Medicine, Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA, 15260, USA
| | - Andrew E Brereton
- Department of Biochemistry and Biophysics, 2011 Ag & Life Sciences Bldg, Oregon State University, Corvallis, OR, 97331, USA
| | - In-Ja L Byeon
- Department of Structural Biology and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh, School of Medicine, Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA, 15260, USA
| | - P Andrew Karplus
- Department of Biochemistry and Biophysics, 2011 Ag & Life Sciences Bldg, Oregon State University, Corvallis, OR, 97331, USA
| | - Angela M Gronenborn
- Department of Structural Biology and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh, School of Medicine, Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA, 15260, USA.
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18
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Li A, Gong S, Johnson KA. Rate-limiting Pyrophosphate Release by HIV Reverse Transcriptase Improves Fidelity. J Biol Chem 2016; 291:26554-26565. [PMID: 27777304 DOI: 10.1074/jbc.m116.753152] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/20/2016] [Indexed: 11/06/2022] Open
Abstract
Previous measurements of the rates of polymerization and pyrophosphate release with DNA templates showed that pyrophosphate (PPi) dissociation was fast after nucleotide incorporation so that it did not contribute to enzyme specificity (kcat/Km). Here, kinetic parameters governing nucleotide incorporation and PPi release were determined using an RNA template. Compared with a DNA template of the same sequence, the rate of chemistry increased by up to 10-fold (250 versus 24 s-1), whereas the rate of PPi release decreased to approximately 58 s-1 so that PPi release became the rate-limiting step. During processive nucleotide incorporation, the first nucleotide (TTP) was incorporated at a fast rate (152 s-1), whereas the rates of incorporation of remaining nucleotides (CGTCG) were much slower with an average rate of 24 s-1, suggesting that sequential incorporation events were limited by the relatively slow PPi release step. The accompanying paper shows that slow PPi release allows polymerization and RNase H to occur at comparable rates. Although PPi release is the rate-determining step, it is not the specificity-determining step for correct incorporation based on our current estimates of the rate of reversal of the chemistry step (3 s-1). In contrast, during misincorporation, PPi release became extremely slow, which we estimated to be ∼0.002 s-1 These studies establish the mechanistic basis for DNA polymerase fidelity during reverse transcription and provide a free energy profile. We correct previous underestimates of discrimination by including the slow PPi release step. Our current estimate of 2.4 × 106 is >20-fold greater than estimated previously.
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Affiliation(s)
- An Li
- From the University of Texas at Austin, Institute for Cell and Molecular Biology, Department of Molecular Biosciences, Austin, Texas 78712
| | - Shanzhong Gong
- From the University of Texas at Austin, Institute for Cell and Molecular Biology, Department of Molecular Biosciences, Austin, Texas 78712
| | - Kenneth A Johnson
- From the University of Texas at Austin, Institute for Cell and Molecular Biology, Department of Molecular Biosciences, Austin, Texas 78712
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19
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Das K, Balzarini J, Miller MT, Maguire AR, DeStefano JJ, Arnold E. Conformational States of HIV-1 Reverse Transcriptase for Nucleotide Incorporation vs Pyrophosphorolysis-Binding of Foscarnet. ACS Chem Biol 2016; 11:2158-64. [PMID: 27192549 DOI: 10.1021/acschembio.6b00187] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
HIV-1 reverse transcriptase (RT) catalytically incorporates individual nucleotides into a viral DNA strand complementing an RNA or DNA template strand; the polymerase active site of RT adopts multiple conformational and structural states while performing this task. The states associated are dNTP binding at the N site, catalytic incorporation of a nucleotide, release of a pyrophosphate, and translocation of the primer 3'-end to the P site. Structural characterization of each of these states may help in understanding the molecular mechanisms of drug activity and resistance and in developing new RT inhibitors. Using a 38-mer DNA template-primer aptamer as the substrate mimic, we crystallized an RT/dsDNA complex that is catalytically active, yet translocation-incompetent in crystals. The ability of RT to perform dNTP binding and incorporation in crystals permitted obtaining a series of structures: (I) RT/DNA (P-site), (II) RT/DNA/AZTTP ternary, (III) RT/AZT-terminated DNA (N-site), and (IV) RT/AZT-terminated DNA (N-site)/foscarnet complexes. The stable N-site complex permitted the binding of foscarnet as a pyrophosphate mimic. The Mg(2+) ions dissociated after catalytic addition of AZTMP in the pretranslocated structure III, whereas ions A and B had re-entered the active site to bind foscarnet in structure IV. The binding of foscarnet involves chelation with the Mg(2+) (B) ion and interactions with K65 and R72. The analysis of interactions of foscarnet and the recently discovered nucleotide-competing RT inhibitor (NcRTI) α-T-CNP in two different conformational states of the enzyme provides insights for developing new classes of polymerase active site RT inhibitors.
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Affiliation(s)
- Kalyan Das
- Center
for Advanced Biotechnology and Medicine (CABM), Department of Chemistry
and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States
| | - Jan Balzarini
- Rega
Institute for Medical Research and Department of Microbiology and
Immunology, KU Leuven, B-3000 Leuven, Belgium
| | - Matthew T. Miller
- Center
for Advanced Biotechnology and Medicine (CABM), Department of Chemistry
and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States
| | - Anita R. Maguire
- Department
of Chemistry and School of Pharmacy, Analytical and Biological Chemistry
Research Facility, Synthesis and Solid State Pharmaceutical Centre, University College Cork, Cork, Ireland
| | - Jeffrey J. DeStefano
- Department
of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, Maryland, United States
| | - Eddy Arnold
- Center
for Advanced Biotechnology and Medicine (CABM), Department of Chemistry
and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States
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20
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Structural basis of HIV inhibition by translocation-defective RT inhibitor 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA). Proc Natl Acad Sci U S A 2016; 113:9274-9. [PMID: 27489345 DOI: 10.1073/pnas.1605223113] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is the most potent nucleoside analog inhibitor of HIV reverse transcriptase (RT). It retains a 3'-OH yet acts as a chain-terminating agent by diminishing translocation from the pretranslocation nucleotide-binding site (N site) to the posttranslocation primer-binding site (P site). Also, facile misincorporation of EFdA-monophosphate (MP) results in difficult-to-extend mismatched primers. To understand the high potency and unusual inhibition mechanism of EFdA, we solved RT crystal structures (resolutions from 2.4 to 2.9 Å) that include inhibition intermediates (i) before inhibitor incorporation (catalytic complex, RT/DNA/EFdA-triphosphate), (ii) after incorporation of EFdA-MP followed by dT-MP (RT/DNAEFdA-MP(P)• dT-MP(N) ), or (iii) after incorporation of two EFdA-MPs (RT/DNAEFdA-MP(P)• EFdA-MP(N) ); (iv) the latter was also solved with EFdA-MP mismatched at the N site (RT/DNAEFdA-MP(P)• EFdA-MP(*N) ). We report that the inhibition mechanism and potency of EFdA stem from interactions of its 4'-ethynyl at a previously unexploited conserved hydrophobic pocket in the polymerase active site. The high resolution of the catalytic complex structure revealed a network of ordered water molecules at the polymerase active site that stabilize enzyme interactions with nucleotide and DNA substrates. Finally, decreased translocation results from favorable interactions of primer-terminating EFdA-MP at the pretranslocation site and unfavorable posttranslocation interactions that lead to observed localized primer distortions.
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21
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Abstract
The enzyme reverse transcriptase (RT) was discovered in retroviruses almost 50 years ago. The demonstration that other types of viruses, and what are now called retrotransposons, also replicated using an enzyme that could copy RNA into DNA came a few years later. The intensity of the research in both the process of reverse transcription and the enzyme RT was greatly stimulated by the recognition, in the mid-1980s, that human immunodeficiency virus (HIV) was a retrovirus and by the fact that the first successful anti-HIV drug, azidothymidine (AZT), is a substrate for RT. Although AZT monotherapy is a thing of the past, the most commonly prescribed, and most successful, combination therapies still involve one or both of the two major classes of anti-RT drugs. Although the basic mechanics of reverse transcription were worked out many years ago, and the first high-resolution structures of HIV RT are now more than 20 years old, we still have much to learn, particularly about the roles played by the host and viral factors that make the process of reverse transcription much more efficient in the cell than in the test tube. Moreover, we are only now beginning to understand how various host factors that are part of the innate immunity system interact with the process of reverse transcription to protect the host-cell genome, the host cell, and the whole host, from retroviral infection, and from unwanted retrotransposition.
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22
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Nakamura A, Tamura N, Yasutake Y. Structure of the HIV-1 reverse transcriptase Q151M mutant: insights into the inhibitor resistance of HIV-1 reverse transcriptase and the structure of the nucleotide-binding pocket of Hepatitis B virus polymerase. Acta Crystallogr F Struct Biol Commun 2015; 71:1384-90. [PMID: 26527265 PMCID: PMC4631587 DOI: 10.1107/s2053230x15017896] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 09/24/2015] [Indexed: 02/08/2023] Open
Abstract
Hepatitis B virus polymerase (HBV Pol) is an important target for anti-HBV drug development; however, its low solubility and stability in vitro has hindered detailed structural studies. Certain nucleotide reverse transcriptase (RT) inhibitors (NRTIs) such as tenofovir and lamivudine can inhibit both HBV Pol and Human immunodeficiency virus 1 (HIV-1) RT, leading to speculation on structural and mechanistic analogies between the deoxynucleotide triphosphate (dNTP)-binding sites of these enzymes. The Q151M mutation in HIV-1 RT, located at the dNTP-binding site, confers resistance to various NRTIs, while maintaining sensitivity to tenofovir and lamivudine. The residue corresponding to Gln151 is strictly conserved as a methionine in HBV Pol. Therefore, the structure of the dNTP-binding pocket of the HIV-1 RT Q151M mutant may reflect that of HBV Pol. Here, the crystal structure of HIV-1 RT Q151M, determined at 2.6 Å resolution, in a new crystal form with space group P321 is presented. Although the structure of HIV-1 RT Q151M superimposes well onto that of HIV-1 RT in a closed conformation, a slight movement of the β-strands (β2-β3) that partially create the dNTP-binding pocket was observed. This movement might be caused by the introduction of the bulky thioether group of Met151. The structure also highlighted the possibility that the hydrogen-bonding network among amino acids and NRTIs is rearranged by the Q151M mutation, leading to a difference in the affinity of NRTIs for HIV-1 RT and HBV Pol.
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Affiliation(s)
- Akiyoshi Nakamura
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira, Sapporo, Hokkaido 062-8517, Japan
| | - Noriko Tamura
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira, Sapporo, Hokkaido 062-8517, Japan
| | - Yoshiaki Yasutake
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira, Sapporo, Hokkaido 062-8517, Japan
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23
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The Nucleoside Analog BMS-986001 Shows Greater In Vitro Activity against HIV-2 than against HIV-1. Antimicrob Agents Chemother 2015; 59:7437-46. [PMID: 26392486 DOI: 10.1128/aac.01326-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 09/11/2015] [Indexed: 02/07/2023] Open
Abstract
Treatment options for individuals infected with human immunodeficiency virus type 2 (HIV-2) are restricted by the intrinsic resistance of the virus to nonnucleoside reverse transcriptase inhibitors (NNRTIs) and the reduced susceptibility of HIV-2 to several protease inhibitors (PIs) used in antiretroviral therapy (ART). In an effort to identify new antiretrovirals for HIV-2 treatment, we evaluated the in vitro activity of the investigational nucleoside analog BMS-986001 (2',3'-didehydro-3'-deoxy-4'-ethynylthymidine; also known as censavudine, festinavir, OBP-601, 4'-ethynyl stavudine, or 4'-ethynyl-d4T). In single-cycle assays, BMS-986001 inhibited HIV-2 isolates from treatment-naive individuals, with 50% effective concentrations (EC50s) ranging from 30 to 81 nM. In contrast, EC50s for group M and O isolates of HIV-1 ranged from 450 to 890 nM. Across all isolates tested, the average EC50 for HIV-2 was 9.5-fold lower than that for HIV-1 (64 ± 18 nM versus 610 ± 200 nM, respectively; mean ± standard deviation). BMS-986001 also exhibited full activity against HIV-2 variants whose genomes encoded the single amino acid changes K65R and Q151M in reverse transcriptase, whereas the M184V mutant was 15-fold more resistant to the drug than the parental HIV-2ROD9 strain. Taken together, our findings show that BMS-986001 is an effective inhibitor of HIV-2 replication. To our knowledge, BMS-986001 is the first nucleoside analog that, when tested against a diverse collection of HIV-1 and HIV-2 isolates, exhibits more potent activity against HIV-2 than against HIV-1 in culture.
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24
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Yamada K, Wahba AS, Bernatchez JA, Ilina T, Martínez-Montero S, Habibian M, Deleavey GF, Götte M, Parniak MA, Damha MJ. Nucleotide Sugar Pucker Preference Mitigates Excision by HIV-1 RT. ACS Chem Biol 2015; 10:2024-33. [PMID: 26131619 DOI: 10.1021/acschembio.5b00263] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of DNA primers containing nucleotides with various sugar pucker conformations at the 3'-terminus were chemically synthesized by solid-phase synthesis. The ability of wild-type (WT) HIV-1 reverse transcriptase (RT) and AZT-resistant (AZTr) RT to excise the 3'-terminal nucleotide was assessed. Nucleosides with a preference for the North conformation were more refractory to excision by both WT-RT and AZTr-RT. We found that DNA primers that contain North puckered-nucleotides at the 3'-terminus can also affect the translocation status of the RT/template/primer complex, which provides an underlying mechanism to avoid being excised. Together, these results point to a correlation between the sugar conformation of the 3'-terminal nucleotide, the precise position of HIV-1 RT on its nucleic acid substrate, and, in turn, its catalytic function. Nucleotide sugar conformation is therefore an important parameter in defining the susceptibility to RT-catalyzed phosphorolytic excision.
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Affiliation(s)
- Ken Yamada
- Department
of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Alexander S. Wahba
- Department
of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Jean A. Bernatchez
- Department
of Biochemistry, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec H3G1Y6, Canada
| | - Tatiana Ilina
- Department
of Microbiology and Molecular Genetics, School of Medicine, University of Pittsburgh, 450 Technology Drive, Pittsburgh, Pennsylvania 15219-3143, United States
| | - Saúl Martínez-Montero
- Department
of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Maryam Habibian
- Department
of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Glen F. Deleavey
- Department
of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Matthias Götte
- Department
of Biochemistry, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec H3G1Y6, Canada
- Department
of Microbiology and Immunology, McGill University, 3775 University, Montreal, Quebec H3A 2B4, Canada
| | - Michael A. Parniak
- Department
of Microbiology and Molecular Genetics, School of Medicine, University of Pittsburgh, 450 Technology Drive, Pittsburgh, Pennsylvania 15219-3143, United States
| | - Masad J. Damha
- Department
of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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25
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Analysis of the Zidovudine Resistance Mutations T215Y, M41L, and L210W in HIV-1 Reverse Transcriptase. Antimicrob Agents Chemother 2015; 59:7184-96. [PMID: 26324274 DOI: 10.1128/aac.05069-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 08/23/2015] [Indexed: 01/01/2023] Open
Abstract
Although anti-human immunodeficiency virus type 1 (HIV-1) therapies have become more sophisticated and more effective, drug resistance continues to be a major problem. Zidovudine (azidothymidine; AZT) was the first nucleoside reverse transcriptase (RT) inhibitor (NRTI) approved for the treatment of HIV-1 infections and is still being used, particularly in the developing world. This drug targets the conversion of single-stranded RNA to double-stranded DNA by HIV-1 RT. However, resistance to the drug quickly appeared both in viruses replicating in cells in culture and in patients undergoing AZT monotherapy. The primary resistance pathway selects for mutations of T215 that change the threonine to either a tyrosine or a phenylalanine (T215Y/F); this resistance pathway involves an ATP-dependent excision mechanism. The pseudo-sugar ring of AZT lacks a 3' OH; RT incorporates AZT monophosphate (AZTMP), which blocks the end of the viral DNA primer. AZT-resistant forms of HIV-1 RT use ATP in an excision reaction to unblock the 3' end of the primer strand, allowing its extension by RT. The T215Y AZT resistance mutation is often accompanied by two other mutations, M41L and L210W. In this study, the roles of these mutations, in combination with T215Y, were examined to determine whether they affect polymerization and excision by HIV-1 RT. The M41L mutation appears to help restore the DNA polymerization activity of RT containing the T215Y mutation and also enhances AZTMP excision. The L210W mutation plays a similar role, but it enhances excision by RTs that carry the T215Y mutation when ATP is present at a low concentration.
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Schneider A, Schweimer K, Rösch P, Wöhrl BM. AZT resistance alters enzymatic properties and creates an ATP-binding site in SFVmac reverse transcriptase. Retrovirology 2015; 12:21. [PMID: 25808094 PMCID: PMC4359774 DOI: 10.1186/s12977-015-0147-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 01/27/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The replication of simian foamy virus from macaques can be inhibited by the nucleoside reverse transcriptase inhibitor azidothymidine (AZT, zidovudine). Four substitutions in the protease-reverse transcriptase (PR-RT) protein (K211I, I224T, S345T, E350K) are necessary to obtain highly AZT resistant and fully replication competent virus. AZT resistance is based on the excision of the incorporated AZTMP in the presence of ATP. I224T is a polymorphism which is not essential for AZT resistance per se, but is important for regaining efficient replication of the resistant virus. RESULTS We constructed PR-RT enzymes harboring one to four amino acid substitutions to analyze them biochemically and to determine their ability to remove the incorporated AZTMP. S345T is the only single substitution variant exhibiting significant AZTMP excision activity. Although K211I alone showed no AZTMP excision activity, excision efficiency doubled when K211I was present in combination with S345T and E350K. K211I also decreased nucleotide binding affinity and increased fidelity. NMR titration experiments revealed that a truncated version of the highly AZT resistant mt4 variant, comprising only the fingers-palm subdomains was able to bind ATP with a KD-value of ca. 7.6 mM, whereas no ATP binding could be detected in the corresponding wild type protein. We could show by NMR spectroscopy that S345T is responsible for ATP binding, probably by making a tryptophan residue accessible. CONCLUSION Although AZT resistance in SFVmac is based on excision of the incorporated AZTMP like in HIV-1, the functions of the resistance substitutions in SFVmac PR-RT appear to be different. No mutation resulting in an aromatic residue like F/Y215 in HIV, which is responsible for π-π-stacking interactions with ATP, is present in SFVmac. Instead, S345T is responsible for creating an ATP binding site, probably by making an already existing tryptophan more accessible, which in turn can interact with ATP. This is in contrast to HIV-1 RT, in which an ATP binding site is present in the WT RT but differs from that of the AZT resistant enzyme.
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A cell-based strategy to assess intrinsic inhibition efficiencies of HIV-1 reverse transcriptase inhibitors. Antimicrob Agents Chemother 2014; 59:838-48. [PMID: 25403670 DOI: 10.1128/aac.04163-14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
During HIV-1 reverse transcription, there are increasing opportunities for nucleos(t)ide (NRTI) or nonnucleoside (NNRTI) reverse transcriptase (RT) inhibitors to stop elongation of the nascent viral DNA (vDNA). In addition, RT inhibitors appear to influence the kinetics of vDNA synthesis differently. While cell-free kinetic inhibition constants have provided detailed mechanistic insight, these assays are dependent on experimental conditions that may not mimic the cellular milieu. Here we describe a novel cell-based strategy to provide a measure of the intrinsic inhibition efficiencies of clinically relevant RT inhibitors on a per-stop-site basis. To better compare inhibition efficiencies among HIV-1 RT inhibitors that can stop reverse transcription at any number of different stop sites, their basic probability, p, of getting stopped at any potential stop site was determined. A relationship between qPCR-derived 50% effective inhibitory concentrations (EC50s) and this basic probability enabled determination of p by successive approximation. On a per-stop-site basis, tenofovir (TFV) exhibited 1.4-fold-greater inhibition efficiency than emtricitabine (FTC), and as a class, both NRTIs exhibited an 8- to 11-fold greater efficiency than efavirenz (EFV). However, as more potential stops sites were considered, the probability of reverse transcription failing to reach the end of the template approached equivalence between both classes of RT inhibitors. Overall, this novel strategy provides a quantitative measure of the intrinsic inhibition efficiencies of RT inhibitors in the natural cellular milieu and thus may further understanding of drug efficacy. This approach also has applicability for understanding the impact of viral polymerase-based inhibitors (alone or in combination) in other virus systems.
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Bernatchez JA, Paul R, Tchesnokov EP, Ngure M, Beilhartz GL, Berghuis AM, Lavoie R, Li L, Auger A, Melnyk RA, Grobler JA, Miller MD, Hazuda DJ, Hecht SM, Götte M. Derivatives of mesoxalic acid block translocation of HIV-1 reverse transcriptase. J Biol Chem 2014; 290:1474-84. [PMID: 25355312 DOI: 10.1074/jbc.m114.614305] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The pyrophosphate mimic and broad spectrum antiviral phosphonoformic acid (PFA, foscarnet) was shown to freeze the pre-translocational state of the reverse transcriptase (RT) complex of the human immunodeficiency virus type 1 (HIV-1). However, PFA lacks a specificity domain, which is seen as a major reason for toxic side effects associated with the clinical use of this drug. Here, we studied the mechanism of inhibition of HIV-1 RT by the 4-chlorophenylhydrazone of mesoxalic acid (CPHM) and demonstrate that this compound also blocks RT translocation. Hot spots for inhibition with PFA or CPHM occur at template positions with a bias toward pre-translocation. Mutations at active site residue Asp-185 compromise binding of both compounds. Moreover, divalent metal ions are required for the formation of ternary complexes with either of the two compounds. However, CPHM contains both an anchor domain that likely interacts with the catalytic metal ions and a specificity domain. Thus, although the inhibitor binding sites may partly overlap, they are not identical. The K65R mutation in HIV-1 RT, which reduces affinity to PFA, increases affinity to CPHM. Details with respect to the binding sites of the two inhibitors are provided on the basis of mutagenesis studies, structure-activity relationship analyses with newly designed CPHM derivatives, and in silico docking experiments. Together, these findings validate the pre-translocated complex of HIV-1 RT as a specific target for the development of novel classes of RT inhibitors.
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Affiliation(s)
- Jean A Bernatchez
- From the Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Rakesh Paul
- the Biodesign Institute and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287
| | - Egor P Tchesnokov
- the Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Marianne Ngure
- the Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Greg L Beilhartz
- the Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Albert M Berghuis
- From the Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada, the Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Rico Lavoie
- Merck Research Laboratories, West Point, Pennsylvania 19486-8000, and
| | - Lianhai Li
- Merck Research Laboratories, West Point, Pennsylvania 19486-8000, and
| | - Anick Auger
- Merck Research Laboratories, West Point, Pennsylvania 19486-8000, and
| | - Roman A Melnyk
- Merck Research Laboratories, West Point, Pennsylvania 19486-8000, and
| | - Jay A Grobler
- Merck Research Laboratories, West Point, Pennsylvania 19486-8000, and
| | - Michael D Miller
- Merck Research Laboratories, West Point, Pennsylvania 19486-8000, and
| | - Daria J Hazuda
- Merck Research Laboratories, West Point, Pennsylvania 19486-8000, and
| | - Sidney M Hecht
- the Biodesign Institute and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287
| | - Matthias Götte
- From the Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada, the Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada, the Department of Medicine, Division of Experimental Medicine, McGill University, Quebec H3A 1A3, Canada
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Novel high-throughput screen identifies an HIV-1 reverse transcriptase inhibitor with a unique mechanism of action. Biochem J 2014; 462:425-32. [PMID: 24969820 DOI: 10.1042/bj20140365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
HIV-1 resistance to zidovudine [AZT (azidothymidine)] is associated with selection of the mutations M41L, D67N, K70R, L210W, T215F/Y and K219Q/E in RT (reverse transcriptase). These mutations decrease HIV-1 susceptibility to AZT by augmenting RT's ability to excise the chain-terminating AZT-MP (AZT-monophosphate) moiety from the chain-terminated DNA primer. Although AZT-MP excision occurs at the enzyme's polymerase active site, it is mechanistically distinct from the DNA polymerase reaction. Consequently, this activity represents a novel target for drug discovery, and inhibitors that target this activity may increase the efficacy of nucleoside/nucleotide analogues, and may help to delay the onset of drug resistance. In the present study, we have developed a FRET (Förster resonance energy transfer)-based high-throughput screening assay for the AZT-MP excision activity of RT. This assay is sensitive and robust, and demonstrates a signal-to-noise ratio of 3.3 and a Z' factor of 0.69. We screened three chemical libraries (7265 compounds) using this assay, and identified APEX57219 {3,3'-[(3-carboxy-4-oxo-2,5-cyclohexadien-1-ylidene)methylene]bis[6-hydroxybenzoic acid]} as the most promising hit. APEX57219 displays a unique activity profile against wild-type and drug-resistant HIV-1 RT, and was found to inhibit virus replication at the level of reverse transcription. Mechanistic analyses revealed that APEX57219 blocked the interaction between RT and the nucleic acid substrate.
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Singh K, Flores JA, Kirby KA, Neogi U, Sonnerborg A, Hachiya A, Das K, Arnold E, McArthur C, Parniak M, Sarafianos SG. Drug resistance in non-B subtype HIV-1: impact of HIV-1 reverse transcriptase inhibitors. Viruses 2014; 6:3535-62. [PMID: 25254383 PMCID: PMC4189038 DOI: 10.3390/v6093535] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 09/09/2014] [Accepted: 09/09/2014] [Indexed: 01/20/2023] Open
Abstract
Human immunodeficiency virus (HIV) causes approximately 2.5 million new infections every year, and nearly 1.6 million patients succumb to HIV each year. Several factors, including cross-species transmission and error-prone replication have resulted in extraordinary genetic diversity of HIV groups. One of these groups, known as group M (main) contains nine subtypes (A-D, F-H and J-K) and causes ~95% of all HIV infections. Most reported data on susceptibility and resistance to anti-HIV therapies are from subtype B HIV infections, which are prevalent in developed countries but account for only ~12% of all global HIV infections, whereas non-B subtype HIV infections that account for ~88% of all HIV infections are prevalent primarily in low and middle-income countries. Although the treatments for subtype B infections are generally effective against non-B subtype infections, there are differences in response to therapies. Here, we review how polymorphisms, transmission efficiency of drug-resistant strains, and differences in genetic barrier for drug resistance can differentially alter the response to reverse transcriptase-targeting therapies in various subtypes.
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Affiliation(s)
- Kamalendra Singh
- Christopher Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
| | - Jacqueline A Flores
- Christopher Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
| | - Karen A Kirby
- Christopher Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
| | - Ujjwal Neogi
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Stockholm 141 86, Sweden.
| | - Anders Sonnerborg
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Stockholm 141 86, Sweden.
| | - Atsuko Hachiya
- Clinical Research Center, Department of Infectious Diseases and Immunology, National Hospital Organization, Nagoya Medical Center, Nagoya 460-0001, Japan.
| | - Kalyan Das
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ 08854, USA.
| | - Eddy Arnold
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ 08854, USA.
| | - Carole McArthur
- Department of Oral and Craniofacial Science , School of Dentistry, University of Missouri, Kansas City, MO 64108, USA.
| | - Michael Parniak
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
| | - Stefan G Sarafianos
- Christopher Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
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Michailidis E, Huber AD, Ryan EM, Ong YT, Leslie MD, Matzek KB, Singh K, Marchand B, Hagedorn AN, Kirby KA, Rohan LC, Kodama EN, Mitsuya H, Parniak MA, Sarafianos SG. 4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) inhibits HIV-1 reverse transcriptase with multiple mechanisms. J Biol Chem 2014; 289:24533-48. [PMID: 24970894 DOI: 10.1074/jbc.m114.562694] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a nucleoside analog that, unlike approved anti-human immunodeficiency virus type 1 (HIV-1) nucleoside reverse transcriptase inhibitors, has a 3'-OH and exhibits remarkable potency against wild-type and drug-resistant HIVs. EFdA triphosphate (EFdA-TP) is unique among nucleoside reverse transcriptase inhibitors because it inhibits HIV-1 reverse transcriptase (RT) with multiple mechanisms. (a) EFdA-TP can block RT as a translocation-defective RT inhibitor that dramatically slows DNA synthesis, acting as a de facto immediate chain terminator. Although non-translocated EFdA-MP-terminated primers can be unblocked, they can be efficiently converted back to the EFdA-MP-terminated form. (b) EFdA-TP can function as a delayed chain terminator, allowing incorporation of an additional dNTP before blocking DNA synthesis. In such cases, EFdA-MP-terminated primers are protected from excision. (c) EFdA-MP can be efficiently misincorporated by RT, leading to mismatched primers that are extremely hard to extend and are also protected from excision. The context of template sequence defines the relative contribution of each mechanism and affects the affinity of EFdA-MP for potential incorporation sites, explaining in part the lack of antagonism between EFdA and tenofovir. Changes in the type of nucleotide before EFdA-MP incorporation can alter its mechanism of inhibition from delayed chain terminator to immediate chain terminator. The versatility of EFdA in inhibiting HIV replication by multiple mechanisms may explain why resistance to EFdA is more difficult to emerge.
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Affiliation(s)
- Eleftherios Michailidis
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Andrew D Huber
- From the Christopher Bond Life Sciences Center and Departments of Veterinary Pathobiology and
| | - Emily M Ryan
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Yee T Ong
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Maxwell D Leslie
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Kayla B Matzek
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Kamalendra Singh
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Bruno Marchand
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Ariel N Hagedorn
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Karen A Kirby
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211
| | - Lisa C Rohan
- Magee-Womens Research Institute and Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Eiichi N Kodama
- Division of Emerging Infectious Diseases, Tohoku University, Sendai 980-8575, Japan
| | - Hiroaki Mitsuya
- Department of Internal Medicine, Kumamoto University, Kumamoto 860-8556, Japan, Experimental Retrovirology Section, HIV/AIDS Malignancy Branch, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Michael A Parniak
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15219
| | - Stefan G Sarafianos
- From the Christopher Bond Life Sciences Center and Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65211, Biochemistry, University of Missouri, Columbia, Missouri 65211,
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Xu C, Maxwell BA, Suo Z. Conformational dynamics of Thermus aquaticus DNA polymerase I during catalysis. J Mol Biol 2014; 426:2901-2917. [PMID: 24931550 DOI: 10.1016/j.jmb.2014.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 06/02/2014] [Accepted: 06/07/2014] [Indexed: 11/15/2022]
Abstract
Despite the fact that DNA polymerases have been investigated for many years and are commonly used as tools in a number of molecular biology assays, many details of the kinetic mechanism they use to catalyze DNA synthesis remain unclear. Structural and kinetic studies have characterized a rapid, pre-catalytic open-to-close conformational change of the Finger domain during nucleotide binding for many DNA polymerases including Thermus aquaticus DNA polymerase I (Taq Pol), a thermostable enzyme commonly used for DNA amplification in PCR. However, little has been performed to characterize the motions of other structural domains of Taq Pol or any other DNA polymerase during catalysis. Here, we used stopped-flow Förster resonance energy transfer to investigate the conformational dynamics of all five structural domains of the full-length Taq Pol relative to the DNA substrate during nucleotide binding and incorporation. Our study provides evidence for a rapid conformational change step induced by dNTP binding and a subsequent global conformational transition involving all domains of Taq Pol during catalysis. Additionally, our study shows that the rate of the global transition was greatly increased with the truncated form of Taq Pol lacking the N-terminal domain. Finally, we utilized a mutant of Taq Pol containing a de novo disulfide bond to demonstrate that limiting protein conformational flexibility greatly reduced the polymerization activity of Taq Pol.
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Affiliation(s)
- Cuiling Xu
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Brian A Maxwell
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Ohio State Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Zucai Suo
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.,Ohio State Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
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Schauer G, Leuba S, Sluis-Cremer N. Biophysical Insights into the Inhibitory Mechanism of Non-Nucleoside HIV-1 Reverse Transcriptase Inhibitors. Biomolecules 2013; 3:889-904. [PMID: 24970195 PMCID: PMC4030976 DOI: 10.3390/biom3040889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/22/2013] [Accepted: 10/22/2013] [Indexed: 12/16/2022] Open
Abstract
HIV-1 reverse transcriptase (RT) plays a central role in HIV infection. Current United States Federal Drug Administration (USFDA)-approved antiretroviral therapies can include one of five approved non-nucleoside RT inhibitors (NNRTIs), which are potent inhibitors of RT activity. Despite their crucial clinical role in treating and preventing HIV-1 infection, their mechanism of action remains elusive. In this review, we introduce RT and highlight major advances from experimental and computational biophysical experiments toward an understanding of RT function and the inhibitory mechanism(s) of NNRTIs.
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Affiliation(s)
- Grant Schauer
- Program in Molecular Biophysics and Structural Biology, Hillman Cancer Center, University of Pittsburgh, 5117 Centre Ave., Pittsburgh, PA 15213, USA.
| | - Sanford Leuba
- Program in Molecular Biophysics and Structural Biology, Hillman Cancer Center, University of Pittsburgh, 5117 Centre Ave., Pittsburgh, PA 15213, USA.
| | - Nicolas Sluis-Cremer
- Department of Medicine, Division of Infectious Diseases, 3550 Terrace St., Pittsburgh, PA 15261, USA.
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Sirivolu VR, Vernekar SKV, Ilina T, Myshakina NS, Parniak MA, Wang Z. Clicking 3'-azidothymidine into novel potent inhibitors of human immunodeficiency virus. J Med Chem 2013; 56:8765-80. [PMID: 24102161 DOI: 10.1021/jm401232v] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
3'-Azidothymidine (AZT) was the first approved antiviral for the treatment of human immunodeficiency virus (HIV). Reported efforts in clicking the 3'-azido group of AZT have not yielded 1,2,3-triazoles active against HIV or any other viruses. We report herein the first AZT-derived 1,2,3-triazoles with submicromolar potencies against HIV-1. The observed antiviral activities from the cytopathic effect (CPE) based assay were confirmed through a single replication cycle assay. Structure-activity-relationship (SAR) studies revealed two structural features key to antiviral activity: a bulky aromatic ring and the 1,5-substitution pattern on the triazole. Biochemical analysis of the corresponding triphosphates showed lower ATP-mediated nucleotide excision efficiency compared to AZT, which along with molecular modeling suggests a mechanism of preferred translocation of triazoles into the P-site of HIV reverse transcriptase (RT). This mechanism is corroborated with the observed reduction of fold resistance of the triazole analogue to an AZT-resistant HIV variant (9-fold compared to 56-fold with AZT).
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Affiliation(s)
- Venkata Ramana Sirivolu
- Center for Drug Design, Academic Health Center, University of Minnesota , Minneapolis, Minnesota 55455, United States
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Monroe JI, El-Nahal WG, Shirts MR. Investigating the mutation resistance of nonnucleoside inhibitors of HIV-RT using multiple microsecond atomistic simulations. Proteins 2013; 82:130-44. [PMID: 23775803 DOI: 10.1002/prot.24346] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/17/2013] [Accepted: 05/31/2013] [Indexed: 11/06/2022]
Abstract
Inhibiting HIV reverse transcriptase through the use of nonnucleoside reverse transcriptase inhibitors (NNRTIs) has become an essential component in drug regimens for the treatment of HIV. Older NNRTIs, such as nevirapine, are structurally rigid, exhibiting decreased inhibitory function on development of common mutations in the NNRTI-binding pocket, which is located around 10 Å from the catalytically active binding site. The newer generation of drugs, such as rilpivirine, are more flexible and resistant to binding pocket mutations but the mechanism by which they actually inhibit protein function and avoid mutations is not well-understood. To this end, we have performed 2-2.4 µs simulations with explicit solvent in an isobaric-isothermal ensemble of six different systems: apo wild-type, apo K103N/Y181C mutant, nevirapine-bound wild-type, nevirapine-bound mutant, rilpivirine-bound wild type, and rilpivirine-bound mutant. Analysis of protein conformations, principal components of motion, and mutual information between residues points to an inhibitory mechanism in which the primer grip stretches away from the catalytic triad of aspartic acids necessary for polymerization of HIV-encoding DNA, but is still unable to reveal a specific structural mechanism behind mutation resistance.
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Affiliation(s)
- Jacob I Monroe
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia
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Seckler JM, Leioatts N, Miao H, Grossfield A. The interplay of structure and dynamics: insights from a survey of HIV-1 reverse transcriptase crystal structures. Proteins 2013; 81:1792-801. [PMID: 23720322 DOI: 10.1002/prot.24325] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/12/2013] [Accepted: 04/19/2013] [Indexed: 11/07/2022]
Abstract
HIV-1 reverse transcriptase (RT) is a critical drug target for HIV treatment, and understanding the exact mechanisms of its function and inhibition would significantly accelerate the development of new anti-HIV drugs. It is well known that structure plays a critical role in protein function, but for RT, structural information has proven to be insufficient-despite enormous effort-to explain the mechanism of inhibition and drug resistance of non-nucleoside RT inhibitors. We hypothesize that the missing link is dynamics, information about the motions of the system. However, many of the techniques that give the best information about dynamics, such as solution nuclear magnetic resonance and molecular dynamics simulations, cannot be easily applied to a protein as large as RT. As an alternative, we combine elastic network modeling with simultaneous hierarchical clustering of structural and dynamic data. We present an extensive survey of the dynamics of RT bound to a variety of ligands and with a number of mutations, revealing a novel mechanism for drug resistance to non-nucleoside RT inhibitors. Hydrophobic core mutations restore active-state motion to multiple functionally significant regions of HIV-1 RT. This model arises out of a combination of structural and dynamic information, rather than exclusively from one or the other.
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Affiliation(s)
- James M Seckler
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, New York
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Bec G, Meyer B, Gerard MA, Steger J, Fauster K, Wolff P, Burnouf D, Micura R, Dumas P, Ennifar E. Thermodynamics of HIV-1 reverse transcriptase in action elucidates the mechanism of action of non-nucleoside inhibitors. J Am Chem Soc 2013; 135:9743-52. [PMID: 23742167 DOI: 10.1021/ja4018418] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
HIV-1 reverse transcriptase (RT) is a heterodimeric enzyme that converts the genomic viral RNA into proviral DNA. Despite intensive biochemical and structural studies, direct thermodynamic data regarding RT interactions with its substrates are still lacking. Here we addressed the mechanism of action of RT and of non-nucleoside RT inhibitors (NNRTIs) by isothermal titration calorimetry (ITC). Using a new incremental-ITC approach, a step-by-step thermodynamic dissection of the RT polymerization activity showed that most of the driving force for DNA synthesis is provided by initial dNTP binding. Surprisingly, thermodynamic and kinetic data led to a reinterpretation of the mechanism of inhibition of NNRTIs. Binding of NNRTIs to preformed RT/DNA complexes is hindered by a kinetic barrier and NNRTIs mostly interact with free RT. Once formed, RT/NNRTI complexes bind DNA either in a seemingly polymerase-competent orientation or form high-affinity dead-end complexes, both RT/NNRTI/DNA complexes being unable to bind the incoming nucleotide substrate.
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Affiliation(s)
- Guillaume Bec
- Architecture et Réactivité des ARN, CNRS/Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg, France
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39
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Ehteshami M, Nijhuis M, Bernatchez JA, Ablenas CJ, McCormick S, de Jong D, Jochmans D, Götte M. Formation of a quaternary complex of HIV-1 reverse transcriptase with a nucleotide-competing inhibitor and its ATP enhancer. J Biol Chem 2013; 288:17336-46. [PMID: 23598281 DOI: 10.1074/jbc.m112.433441] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleotide-competing reverse transcriptase inhibitors were shown to bind reversibly to the nucleotide-binding site of the reverse transcriptase (RT) enzyme of human immunodeficiency virus type 1 (HIV-1). Here, we show that the presence of ATP can enhance the inhibitory effects of the prototype compound INDOPY-1. We employed a combination of cell-free and cell-based assays to shed light on the underlying molecular mechanism. Binding studies and site-specific footprinting experiments demonstrate the existence of a stable quaternary complex with HIV-1 RT, its nucleic acid substrate, INDOPY-1, and ATP. The complex is frozen in the post-translocational state that usually accommodates the incoming nucleotide substrate. Structure-activity relationship studies show that both the base and the phosphate moieties of ATP are elements that play important roles in enhancing the inhibitory effects of INDOPY-1. In vitro susceptibility measurements with mutant viruses containing amino acid substitutions K70G, V75T, L228R, and K219R in the putative ATP binding pocket revealed unexpectedly a hypersusceptible phenotype with respect to INDOPY-1. The same mutational cluster was previously shown to reduce susceptibility to the pyrophosphate analog phosphonoformic acid. However, in the absence of INDOPY-1, ATP can bind and act as a pyrophosphate donor under conditions that favor formation of the pre-translocated RT complex. We therefore conclude that the mutant enzyme facilitates simultaneous binding of INDOPY-1 and ATP to the post-translocated complex. Based on these data, we propose a model in which the bound ATP traps the inhibitor, which, in turn, compromises its dissociation.
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Affiliation(s)
- Maryam Ehteshami
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
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40
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NTP-mediated nucleotide excision activity of hepatitis C virus RNA-dependent RNA polymerase. Proc Natl Acad Sci U S A 2013; 110:E348-57. [PMID: 23307808 DOI: 10.1073/pnas.1214924110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Hepatitis C virus (HCV) RNA-dependent RNA polymerase replicates the viral genomic RNA and is a primary drug target for antiviral therapy. Previously, we described the purification of an active and stable polymerase-primer-template elongation complex. Here, we show that, unexpectedly, the polymerase elongation complex can use NTPs to excise the terminal nucleotide in nascent RNA. Mismatched ATP, UTP, or CTP could mediate excision of 3'-terminal CMP to generate the dinucleoside tetraphosphate products Ap(4)C, Up(4)C, and Cp(4)C, respectively. Pre-steady-state kinetic studies showed that the efficiency of NTP-mediated excision was highest with ATP. A chain-terminating inhibitor, 3'deoxy-CMP, could also be excised through this mechanism, suggesting important implications for nucleoside drug potency and resistance. The nucleotide excision reaction catalyzed by recombinant hepatitis C virus polymerase was 100-fold more efficient than the corresponding reaction observed with HIV reverse transcriptase.
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41
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Abstract
Reverse transcription and integration are the defining features of the Retroviridae; the common name "retrovirus" derives from the fact that these viruses use a virally encoded enzyme, reverse transcriptase (RT), to convert their RNA genomes into DNA. Reverse transcription is an essential step in retroviral replication. This article presents an overview of reverse transcription, briefly describes the structure and function of RT, provides an introduction to some of the cellular and viral factors that can affect reverse transcription, and discusses fidelity and recombination, two processes in which reverse transcription plays an important role. In keeping with the theme of the collection, the emphasis is on HIV-1 and HIV-1 RT.
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Affiliation(s)
- Wei-Shau Hu
- Viral Recombination Section, HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland 21702-1201, USA
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42
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Lwatula C, Garforth SJ, Prasad VR. Lys66 residue as a determinant of high mismatch extension and misinsertion rates of HIV-1 reverse transcriptase. FEBS J 2012; 279:4010-24. [PMID: 22925131 DOI: 10.1111/j.1742-4658.2012.08807.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 08/21/2012] [Accepted: 08/23/2012] [Indexed: 11/28/2022]
Abstract
A major factor contributing to the high mutation rate of HIV-1 reverse transcriptase (RT) is its high propensity for misincorporation. Misincorporation requires both deoxyribonucleotide triphosphate (dNTP) misinsertion and the subsequent extension of the mismatched terminus thus formed. We hypothesized that Lys66 is a determinant of mismatch extension based on its position near the primer terminus. This hypothesis was tested by steady-state kinetic studies using wild-type HIV-1 RT and four Lys66 substitution mutants: Lys66Arg, Lys66Ala, Lys66Asn and Lys66Thr. The mismatch extension efficiency was reduced for all mutants, with Lys66Ala, Lys66Asn and Lys66Thr showing a four- to six-fold reduction compared with wild-type HIV-1 RT. Surprisingly, the nonconservative substitutions also led to large decreases in misinsertion efficiency, ranging from as low as three-fold to values much higher than 23-fold. Thus, the Lys66Arg mutant was akin to wild-type HIV-1 RT, whereas all nonconservative mutants displayed significantly decreased efficiency for both events. Our results suggest that Lys66, much like Lys65, is a determinant of both dNTP misinsertion and mismatch extension efficiency. While Lys65 is known to contact the γ-phosphate of incoming dNTP, the Lys66 side chain is in the vicinity of the primer terminus. However, our results suggest that both residues have a similar influence on dNTP misinsertion and mispair extension efficiencies of HIV-1 RT. When we tested the mutants for susceptibility to selected nucleoside analog and non-nucleoside analog drugs, similarly to Lys65Arg, the Lys66Ala and Lys66Asn mutants displayed mild resistance to the nucleoside analog drug 3'-azido-3'-deoxythymidine-5'-triphosphate (AZTTP).
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Affiliation(s)
- Chisanga Lwatula
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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43
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Global Conformational Dynamics of HIV-1 Reverse Transcriptase Bound to Non-Nucleoside Inhibitors. BIOLOGY 2012; 1:222-44. [PMID: 24832224 PMCID: PMC4009785 DOI: 10.3390/biology1020222] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 11/16/2022]
Abstract
HIV-1 Reverse Transcriptase (RT) is a multifunctional enzyme responsible for the transcription of the RNA genome of the HIV virus into DNA suitable for incorporation within the DNA of human host cells. Its crucial role in the viral life cycle has made it one of the major targets for antiretroviral drug therapy. The Non-Nucleoside RT Inhibitor (NNRTI) class of drugs binds allosterically to the enzyme, affecting many aspects of its activity. We use both coarse grained network models and atomistic molecular dynamics to explore the changes in protein dynamics induced by NNRTI binding. We identify changes in the flexibility and conformation of residue Glu396 in the RNaseH primer grip which could provide an explanation for the acceleration in RNaseH cleavage rate observed experimentally in NNRTI bound HIV-1 RT. We further suggest a plausible path for conformational and dynamic changes to be communicated from the vicinity of the NNRTI binding pocket to the RNaseH at the other end of the enzyme.
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44
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Hachiya A, Marchand B, Kirby KA, Michailidis E, Tu X, Palczewski K, Ong YT, Li Z, Griffin DT, Schuckmann MM, Tanuma J, Oka S, Singh K, Kodama EN, Sarafianos SG. HIV-1 reverse transcriptase (RT) polymorphism 172K suppresses the effect of clinically relevant drug resistance mutations to both nucleoside and non-nucleoside RT inhibitors. J Biol Chem 2012; 287:29988-99. [PMID: 22761416 DOI: 10.1074/jbc.m112.351551] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Polymorphisms have poorly understood effects on drug susceptibility and may affect the outcome of HIV treatment. We have discovered that an HIV-1 reverse transcriptase (RT) polymorphism (RT(172K)) is present in clinical samples and in widely used laboratory strains (BH10), and it profoundly affects HIV-1 susceptibility to both nucleoside (NRTIs) and non-nucleoside RT inhibitors (NNRTIs) when combined with certain mutations. Polymorphism 172K significantly suppressed zidovudine resistance caused by excision (e.g. thymidine-associated mutations) and not by discrimination mechanism mutations (e.g. Q151M complex). Moreover, it attenuated resistance to nevirapine or efavirenz imparted by NNRTI mutations. Although 172K favored RT-DNA binding at an excisable pre-translocation conformation, it decreased excision by thymidine-associated mutation-containing RT. 172K affected DNA handling and decreased RT processivity without significantly affecting the k(cat)/K(m) values for dNTP. Surface plasmon resonance experiments revealed that RT(172K) decreased DNA binding by increasing the dissociation rate. Hence, the increased zidovudine susceptibility of RT(172K) results from its increased dissociation from the chain-terminated DNA and reduced primer unblocking. We solved a high resolution (2.15 Å) crystal structure of RT mutated at 172 and compared crystal structures of RT(172R) and RT(172K) bound to NNRTIs or DNA/dNTP. Our structural analyses highlight differences in the interactions between α-helix E (where 172 resides) and the active site β9-strand that involve the YMDD loop and the NNRTI binding pocket. Such changes may increase dissociation of DNA, thus suppressing excision-based NRTI resistance and also offset the effect of NNRTI resistance mutations thereby restoring NNRTI binding.
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Affiliation(s)
- Atsuko Hachiya
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO 65211, USA
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45
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Menéndez-Arias L. A structural frame for understanding the role of thymidine analogue resistance mutations in resistance to zidovudine and other nucleoside analogues. Antivir Ther 2012; 16:943-6. [PMID: 22024508 DOI: 10.3851/imp1889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The acquisition of resistance to nucleoside reverse transcriptase inhibitors (NRTIs) can be mediated by amino acid changes at the dNTP binding site that affect the catalytic efficiency of nucleotide analogue incorporation, or by mutations that, in the presence of a pyrophosphate donor, facilitate excision of 3'-terminal chain-terminating inhibitors from blocked primers. These mutations, known as thymidine analogue resistance mutations (TAMs) are M41L, D67N, K70R, L210W, T215F/Y and K219E/Q. Recently published crystal structures of wild-type and TAM-containing HIV-1 reverse transcriptases bound to double-stranded DNA and the excision product, azidothymidine adenosine dinucleoside tetraphosphate have shed light into the molecular mechanism of excision.
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Affiliation(s)
- Luis Menéndez-Arias
- Centro de Biología Molecular 'Severo Ochoa' (Consejo Superior de Investigaciones Científicas & Universidad Autónoma de Madrid), c/ Nicolás Cabrera 1, Campus de Cantoblanco, Madrid, Spain.
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46
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Michailidis E, Kirby KA, Hachiya A, Yoo W, Hong SP, Kim SO, Folk WR, Sarafianos SG. Antiviral therapies: focus on hepatitis B reverse transcriptase. Int J Biochem Cell Biol 2012; 44:1060-71. [PMID: 22531713 DOI: 10.1016/j.biocel.2012.04.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 04/04/2012] [Accepted: 04/05/2012] [Indexed: 12/20/2022]
Abstract
Hepatitis B virus (HBV) is the etiologic agent of mankind's most serious liver disease. While the availability of a vaccine has reduced the number of new HBV infections, the vaccine does not benefit the approximately 350 million people already chronically infected by the virus. Most of the drugs approved by the FDA for the treatment of hepatitis B target the reverse transcriptase (RT or P gene product) and are nucleoside RT inhibitors (NRTIs) that suppress viral replication. However, prolonged monotherapies directed against a single target result in the emergence of viral resistance. HBV genotypic differences affect NRTI resistance, and because the reading frames of the S (surface antigen) and P genes partially overlap, genomic differences that affect the surface of the virus may also alter the viral polymerase sequence, function and drug susceptibility. The scope of this review is to assess the effects of HBV genotypic variation on the development of drug resistance to NRTIs. Some RT residues that vary among different genotypes are in the vicinity of residues that mutate and give rise to NRTI resistance. Interactions between these amino acids can help explain the effect of HBV genotype on the development of NRTI resistance during antiviral therapies, and might help in the design of improved therapeutic strategies.
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Affiliation(s)
- Eleftherios Michailidis
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology & Immunology, University of Missouri, Columbia, MO 65211, USA
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47
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Figueras A, Miralles-Llumà R, Flores R, Rustullet A, Busqué F, Figueredo M, Font J, Alibés R, Maréchal JD. Synthesis, Anti-HIV Activity Studies, and in silico Rationalization of Cyclobutane-Fused Nucleosides. ChemMedChem 2012; 7:1044-56. [DOI: 10.1002/cmdc.201200059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Indexed: 12/22/2022]
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48
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Rubtsova M, Vasilkova D, Malyavko A, Naraikina Y, Zvereva M, Dontsova O. Telomere lengthening and other functions of telomerase. Acta Naturae 2012; 4:44-61. [PMID: 22872811 PMCID: PMC3408703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Telomerase is an enzyme that maintains the length of the telomere. The telomere length specifies the number of divisions a cell can undergo before it finally dies (i.e. the proliferative potential of cells). For example, telomerase is activated in embryonic cell lines and the telomere length is maintained at a constant level; therefore, these cells have an unlimited fission potential. Stem cells are characterized by a lower telomerase activity, which enables only partial compensation for the shortening of telomeres. Somatic cells are usually characterized by the absence of telomerase activity. Telomere shortening leads to the attainment of the Hayflick limit, the transition of cells to a state of senescence. The cells subsequently enter a state of crisis, accompanied by massive cell death. The surviving cells become cancer cells, which are capable both of dividing indefinitely and maintaining telomere length (usually with the aid of telomerase). Telomerase is a reverse transcriptase. It consists of two major components: telomerase RNA (TER) and reverse transcriptase (TERT). TER is a non-coding RNA, and it contains the region which serves as a template for telomere synthesis. An increasing number of articles focussing on the alternative functions of telomerase components have recently started appearing. The present review summarizes data on the structure, biogenesis, and functions of telomerase.
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Affiliation(s)
- M.P. Rubtsova
- Lomonosov Moscow State University, Chemistry Department
- Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State
University
| | | | - A.N. Malyavko
- Lomonosov Moscow State University, Chemistry Department
| | - Yu.V. Naraikina
- Lomonosov Moscow State University, Faculty of Bioengineering and
Bioinformatics
| | - M.I. Zvereva
- Lomonosov Moscow State University, Chemistry Department
- Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State
University
| | - O.A. Dontsova
- Lomonosov Moscow State University, Chemistry Department
- Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State
University
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49
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Structural and inhibition studies of the RNase H function of xenotropic murine leukemia virus-related virus reverse transcriptase. Antimicrob Agents Chemother 2012; 56:2048-61. [PMID: 22252812 DOI: 10.1128/aac.06000-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
RNase H inhibitors (RNHIs) have gained attention as potential HIV-1 therapeutics. Although several RNHIs have been studied in the context of HIV-1 reverse transcriptase (RT) RNase H, there is no information on inhibitors that might affect the RNase H activity of other RTs. We performed biochemical, virological, crystallographic, and molecular modeling studies to compare the RNase H function and inhibition profiles of the gammaretroviral xenotropic murine leukemia virus-related virus (XMRV) and Moloney murine leukemia virus (MoMLV) RTs to those of HIV-1 RT. The RNase H activity of XMRV RT is significantly lower than that of HIV-1 RT and comparable to that of MoMLV RT. XMRV and MoMLV, but not HIV-1 RT, had optimal RNase H activities in the presence of Mn²⁺ and not Mg²⁺. Using hydroxyl-radical footprinting assays, we demonstrated that the distance between the polymerase and RNase H domains in the MoMLV and XMRV RTs is longer than that in the HIV-1 RT by ∼3.4 Å. We identified one naphthyridinone and one hydroxyisoquinolinedione as potent inhibitors of HIV-1 and XMRV RT RNases H with 50% inhibitory concentrations ranging from ∼0.8 to 0.02 μM. Two acylhydrazones effective against HIV-1 RT RNase H were less potent against the XMRV enzyme. We also solved the crystal structure of an XMRV RNase H fragment at high resolution (1.5 Å) and determined the molecular details of the XMRV RNase H active site, thus providing a framework that would be useful for the design of antivirals that target RNase H.
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50
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Kirby TW, DeRose EF, Cavanaugh NA, Beard WA, Shock DD, Mueller GA, Wilson SH, London RE. Metal-induced DNA translocation leads to DNA polymerase conformational activation. Nucleic Acids Res 2011; 40:2974-83. [PMID: 22169953 PMCID: PMC3326329 DOI: 10.1093/nar/gkr1218] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Binding of the catalytic divalent ion to the ternary DNA polymerase β/gapped DNA/dNTP complex is thought to represent the final step in the assembly of the catalytic complex and is consequently a critical determinant of replicative fidelity. We have analyzed the effects of Mg2+ and Zn2+ on the conformational activation process based on NMR measurements of [methyl-13C]methionine DNA polymerase β. Unexpectedly, both divalent metals were able to produce a template base-dependent conformational activation of the polymerase/1-nt gapped DNA complex in the absence of a complementary incoming nucleotide, albeit with different temperature thresholds. This conformational activation is abolished by substituting Glu295 with lysine, thereby interrupting key hydrogen bonds necessary to stabilize the closed conformation. These and other results indicate that metal-binding can promote: translocation of the primer terminus base pair into the active site; expulsion of an unpaired pyrimidine, but not purine, base from the template-binding pocket; and motions of polymerase subdomains that close the active site. We also have performed pyrophosphorolysis studies that are consistent with predictions based on these results. These findings provide new insight into the relationships between conformational activation, enzyme activity and polymerase fidelity.
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Affiliation(s)
- Thomas W Kirby
- Laboratory of Structural Biology, NIEHS, Research Triangle Park, NC 27709, USA
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