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Dakshinamoorthy A, Asmita A, Senapati S. Comprehending the Structure, Dynamics, and Mechanism of Action of Drug-Resistant HIV Protease. ACS OMEGA 2023; 8:9748-9763. [PMID: 36969469 PMCID: PMC10034783 DOI: 10.1021/acsomega.2c08279] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Since the emergence of the Human Immunodeficiency Virus (HIV) in the 1980s, strategies to combat HIV-AIDS are continuously evolving. Among the many tested targets to tackle this virus, its protease enzyme (PR) was proven to be an attractive option that brought about numerous research publications and ten FDA-approved drugs to inhibit the PR activity. However, the drug-induced mutations in the enzyme made these small molecule inhibitors ineffective with prolonged usage. The research on HIV PR, therefore, remains a thrust area even today. Through this review, we reiterate the importance of understanding the various structural and functional components of HIV PR in redesigning the structure-based small molecule inhibitors. We also discuss at length the currently available FDA-approved drugs and how these drug molecules induced mutations in the enzyme structure. We then recapitulate the reported mechanisms on how these drug-resistant variants remain sufficiently active to cleave the natural substrates. We end with the future scope covering the recently proposed strategies that show promise to deal with the mutations.
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Sanusi ZK, Lawal MM, Govender T, Baijnath S, Naicker T, Maguire GEM, Honarparvar B, Kruger HG. Concerted hydrolysis mechanism of HIV-1 natural substrate against subtypes B and C-SA PR: insight through molecular dynamics and hybrid QM/MM studies. Phys Chem Chem Phys 2020; 22:2530-2539. [PMID: 31942584 DOI: 10.1039/c9cp05639d] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It is well known that understanding the catalytic mechanism of HIV-1 PR is the rationale on which its inhibitors were developed; therefore, a better understanding of the mechanism of natural substrate hydrolysis is important. Herein, the reaction mechanism of HIV-1 natural substrates with subtypes B and common mutant in South Africa (subtype C-SA) protease were studied through transition state modelling, using a general acid-general base (GA-GB) one-step concerted process. The activation free energies of enzyme-substrate complexes were compared based on their rate of hydrolysis using a two-layered ONIOM (B3LYP/6-31++G(d,p):AMBER) method. We expanded our computational model to obtain a better understanding of the mechanism of hydrolysis as well as how the enzyme recognises or chooses the cleavage site of the scissile bonds. Using this model, a potential substrate-based inhibitor could be developed with better potency. The calculated activation energies of natural substrates in our previous study correlated well with experimental data. A similar trend was observed for the Gag and Gag-Pol natural substrates in the present work for both enzyme complexes except for the PR-RT substrate. Natural bond orbital (NBO) analysis was also applied to determine the extent of charge transfer within the QM part of both enzymes considered and the PR-RT natural substrate. The result of this study shows that the method can be utilized as a dependable computational technique to rationalize lead compounds against specific targets.
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Affiliation(s)
- Zainab K Sanusi
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
| | - Monsurat M Lawal
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
| | | | - Sooraj Baijnath
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
| | - Tricia Naicker
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
| | - Glenn E M Maguire
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa. and School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Bahareh Honarparvar
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
| | - Hendrik G Kruger
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
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Henes M, Kosovrasti K, Lockbaum GJ, Leidner F, Nachum GS, Nalivaika EA, Bolon DN, Yilmaz NK, Schiffer CA, Whitfield TW. Molecular Determinants of Epistasis in HIV-1 Protease: Elucidating the Interdependence of L89V and L90M Mutations in Resistance. Biochemistry 2019; 58:3711-3726. [PMID: 31386353 PMCID: PMC6941756 DOI: 10.1021/acs.biochem.9b00446] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Protease inhibitors have the highest potency among antiviral therapies against HIV-1 infections, yet the virus can evolve resistance. Darunavir (DRV), currently the most potent Food and Drug Administration-approved protease inhibitor, retains potency against single-site mutations. However, complex combinations of mutations can confer resistance to DRV. While the interdependence between mutations within HIV-1 protease is key for inhibitor potency, the molecular mechanisms that underlie this control remain largely unknown. In this study, we investigated the interdependence between the L89V and L90M mutations and their effects on DRV binding. These two mutations have been reported to be positively correlated with one another in HIV-1 patient-derived protease isolates, with the presence of one mutation making the probability of the occurrence of the second mutation more likely. The focus of our investigation is a patient-derived isolate, with 24 mutations that we call "KY"; this variant includes the L89V and L90M mutations. Three additional KY variants with back-mutations, KY(V89L), KY(M90L), and the KY(V89L/M90L) double mutation, were used to experimentally assess the individual and combined effects of these mutations on DRV inhibition and substrate processing. The enzymatic assays revealed that the KY(V89L) variant, with methionine at residue 90, is highly resistant, but its catalytic function is compromised. When a leucine to valine mutation at residue 89 is present simultaneously with the L90M mutation, a rescue of catalytic efficiency is observed. Molecular dynamics simulations of these DRV-bound protease variants reveal how the L90M mutation induces structural changes throughout the enzyme that undermine the binding interactions.
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Affiliation(s)
- Mina Henes
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Klajdi Kosovrasti
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Gordon J. Lockbaum
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Florian Leidner
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Gily S. Nachum
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Ellen A. Nalivaika
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Daniel N.A. Bolon
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Nese Kurt Yilmaz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Celia A. Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA,Corresponding Author Celia A. Schiffer: Phone: +1 508 856 8008; , Troy W. Whitfield: Phone: +1 508 856 4401;
| | - Troy W. Whitfield
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA,Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA,Corresponding Author Celia A. Schiffer: Phone: +1 508 856 8008; , Troy W. Whitfield: Phone: +1 508 856 4401;
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Accelerating pharmaceutical structure-guided drug design: a successful model. Drug Discov Today 2018; 24:377-381. [PMID: 30448353 DOI: 10.1016/j.drudis.2018.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 10/23/2018] [Accepted: 11/11/2018] [Indexed: 11/22/2022]
Abstract
The impact and value of structure-based drug design to pharmaceutical discovery across the industry are now undeniable, with many break-through therapies on the market that are structure based in nature. Enabling the structural research is the Industrial Macromolecular Crystallography Association-Collaborative Access Team (IMCA-CAT), formed over 25 years ago as a world-class research facility at the synchrotron at Argonne National Laboratory. What makes IMCA-CAT unique is the strategy of the founding consortium to comprehensively provide for the evolving needs of industry in one facility. This includes year-round high-quality data, capabilities that match target portfolios, throughput and capacity that are never limiting, and unfailing security. Here, we illuminate the unique capabilities offered by IMCA-CAT and instruct how all industrial organizations can access this facility.
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Chalcone scaffolds as anti-infective agents: structural and molecular target perspectives. Eur J Med Chem 2015; 101:496-524. [PMID: 26188621 DOI: 10.1016/j.ejmech.2015.06.052] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/27/2015] [Accepted: 06/28/2015] [Indexed: 12/11/2022]
Abstract
In recent years, widespread outbreak of numerous infectious diseases across the globe has created havoc among the population. Particularly, the inhabitants of tropical and sub-tropical regions are mainly affected by these pathogens. Several natural and (semi) synthetic chalcones deserve the credit of being potential anti-infective candidates that inhibit various parasitic, malarial, bacterial, viral, and fungal targets like cruzain-1/2, trypanopain-Tb, trans-sialidase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fumarate reductase, falcipain-1/2, β-hematin, topoisomerase-II, plasmepsin-II, lactate dehydrogenase, protein kinases (Pfmrk and PfPK5), and sorbitol-induced hemolysis, DEN-1 NS3, H1N1, HIV (Integrase/Protease), protein tyrosine phosphatase A/B (Ptp-A/B), FtsZ, FAS-II, lactate/isocitrate dehydrogenase, NorA efflux pump, DNA gyrase, fatty acid synthase, chitin synthase, and β-(1,3)-glucan synthase. In this review, a comprehensive study (from Jan. 1982 to May 2015) of the structural features of anti-infective chalcones, their mechanism of actions (MOAs) and structure activity relationships (SARs) have been highlighted. With the knowledge of molecular targets, structural insights and SARs, this review may be helpful for (medicinal) chemists to design more potent, safe, selective and cost effective anti-infective agents.
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De Conto V, Braz ASK, Perahia D, Scott LPB. Recovery of the wild type atomic flexibility in the HIV-1 protease double mutants. J Mol Graph Model 2015; 59:107-16. [PMID: 25948548 DOI: 10.1016/j.jmgm.2015.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 04/09/2015] [Accepted: 04/17/2015] [Indexed: 02/04/2023]
Abstract
The emergence of drug resistant mutations due to the selective pressure exerted by antiretrovirals, including protease inhibitors (PIs), remains a major problem in the treatment of AIDS. During PIs therapy, the occurrence of primary mutations in the wild type HIV-1 protease reduces both the affinity for the inhibitors and the viral replicative capacity compared to the wild type (WT) protein, but additional mutations compensate for this reduced viral fitness. To investigate this phenomenon from the structural point of view, we combined Molecular Dynamics and Normal Mode Analysis to analyze and compare the variations of the flexibility of C-alpha atoms and the differences in hydrogen bond (h-bond) network between the WT and double mutants. In most cases, the flexibility profile of the double mutants was more often similar to that of the WT than to that of the related single base mutants. All single mutants showed a significant alteration in h-bond formation compared to WT. Most of the significant changes occur in the border between the flap and cantilever regions. We found that all the considered double mutants have their h-bond pattern significantly altered in comparison to the respective single base mutants affecting their flexibility profile that becomes more similar to that of WT. This WT flexibility restoration in the double mutants appears as an important factor for the HIV-1 fitness recovery observed in patients.
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Affiliation(s)
- Valderes De Conto
- Laboratório de Biologia Computacional e Bioinformática, Universidade Federal do ABC, Santo André, SP, Brazil
| | - Antônio S K Braz
- Laboratório de Biologia Computacional e Bioinformática, Universidade Federal do ABC, Santo André, SP, Brazil
| | - David Perahia
- Laboratoire de Biologie et Pharmacologie Appliquée (LBPA), Ecole Normale Supérieure de Cachan, Cachan, France
| | - Luis P B Scott
- Laboratório de Biologia Computacional e Bioinformática, Universidade Federal do ABC, Santo André, SP, Brazil; Laboratoire de Biologie et Pharmacologie Appliquée (LBPA), Ecole Normale Supérieure de Cachan, Cachan, France.
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8
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Variable context Markov chains for HIV protease cleavage site prediction. Biosystems 2009; 96:246-50. [DOI: 10.1016/j.biosystems.2009.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 03/03/2009] [Accepted: 03/12/2009] [Indexed: 11/19/2022]
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Moyle G. Drug Evaluation: Anti-infectives: Saquinavir: A review of its development, pharmacological properties and clinical use. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.5.2.155] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Kovalevsky AY, Chumanevich AA, Liu F, Louis JM, Weber IT. Caught in the Act: the 1.5 A resolution crystal structures of the HIV-1 protease and the I54V mutant reveal a tetrahedral reaction intermediate. Biochemistry 2007; 46:14854-64. [PMID: 18052235 DOI: 10.1021/bi700822g] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
HIV-1 protease (PR) is the target for several important antiviral drugs used in AIDS therapy. The drugs bind inside the active site cavity of PR where normally the viral polyprotein substrate is bound and hydrolyzed. We report two high-resolution crystal structures of wild-type PR (PRWT) and the multi-drug-resistant variant with the I54V mutation (PRI54V) in complex with a peptide at 1.46 and 1.50 A resolution, respectively. The peptide forms a gem-diol tetrahedral reaction intermediate (TI) in the crystal structures. Distinctive interactions are observed for the TI binding in the active site cavity of PRWT and PRI54V. The mutant PRI54V/TI complex has lost water-mediated hydrogen bond interactions with the amides of Ile50 and Ile50' in the flap. Hence, the structures provide insight into the mechanism of drug resistance arising from this mutation. The structures also illustrate an intermediate state in the hydrolysis reaction. One of the gem-diol hydroxide groups in the PRWT complex forms a very short (2.3 A) hydrogen bond with the outer carboxylate oxygen of Asp25. Quantum chemical calculations based on this TI structure are consistent with protonation of the inner carboxylate oxygen of Asp25', in contrast to several theoretical studies. These TI complexes and quantum calculations are discussed in relation to the chemical mechanism of the peptide bond hydrolysis catalyzed by PR.
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Affiliation(s)
- Andrey Y Kovalevsky
- Department of Biology and Chemistry, Molecular Basis of Disease Program, Georgia State University, Atlanta, Georgia 30303, USA
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Marmey P, Rojas-Mendoza A, de Kochko A, Beachy RN, Fauquet CM. Characterization of the protease domain of Rice tungro bacilliform virus responsible for the processing of the capsid protein from the polyprotein. Virol J 2005; 2:33. [PMID: 15831103 PMCID: PMC1087892 DOI: 10.1186/1743-422x-2-33] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Accepted: 04/14/2005] [Indexed: 11/21/2022] Open
Abstract
Background Rice tungro bacilliform virus (RTBV) is a pararetrovirus, and a member of the family Caulimoviridae in the genus Badnavirus. RTBV has a long open reading frame that encodes a large polyprotein (P3). Pararetroviruses show similarities with retroviruses in molecular organization and replication. P3 contains a putative movement protein (MP), the capsid protein (CP), the aspartate protease (PR) and the reverse transcriptase (RT) with a ribonuclease H activity. PR is a member of the cluster of retroviral proteases and serves to proteolytically process P3. Previous work established the N- and C-terminal amino acid sequences of CP and RT, processing of RT by PR, and estimated the molecular mass of PR by western blot assays. Results A molecular mass of a protein that was associated with virions was determined by in-line HPLC electrospray ionization mass spectral analysis. Comparison with retroviral proteases amino acid sequences allowed the characterization of a putative protease domain in this protein. Structural modelling revealed strong resemblance with retroviral proteases, with overall folds surrounding the active site being well conserved. Expression in E. coli of putative domain was affected by the presence or absence of the active site in the construct. Analysis of processing of CP by PR, using pulse chase labelling experiments, demonstrated that the 37 kDa capsid protein was dependent on the presence of the protease in the constructs. Conclusion The findings suggest the characterization of the RTBV protease domain. Sequence analysis, structural modelling, in vitro expression studies are evidence to consider the putative domain as being the protease domain. Analysis of expression of different peptides corresponding to various domains of P3 suggests a processing of CP by PR. This work clarifies the organization of the RTBV polyprotein, and its processing by the RTBV protease.
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Affiliation(s)
- Philippe Marmey
- IRD, UMR «DGPC», B.P. 64501, 34394 Montpellier cedex 5, France
| | - Ana Rojas-Mendoza
- Protein Design Group, Centro Nacional de Biotecnologia, Campus Universidad Autonoma Cantoblanco, 28049 Madrid, Spain
| | | | - Roger N Beachy
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA
| | - Claude M Fauquet
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA
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Maguire MF, Guinea R, Griffin P, Macmanus S, Elston RC, Wolfram J, Richards N, Hanlon MH, Porter DJT, Wrin T, Parkin N, Tisdale M, Furfine E, Petropoulos C, Snowden BW, Kleim JP. Changes in human immunodeficiency virus type 1 Gag at positions L449 and P453 are linked to I50V protease mutants in vivo and cause reduction of sensitivity to amprenavir and improved viral fitness in vitro. J Virol 2002; 76:7398-406. [PMID: 12097552 PMCID: PMC136352 DOI: 10.1128/jvi.76.15.7398-7406.2002] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) Gag protease cleavage sites (CS) undergo sequence changes during the development of resistance to several protease inhibitors (PIs). We have analyzed the association of sequence variation at the p7/p1 and p1/p6 CS in conjunction with amprenavir (APV)-specific protease mutations following PI combination therapy with APV. Querying a central resistance data repository resulted in the detection of significant associations (P < 0.001) between the presence of APV protease signature mutations and Gag L449F (p1/p6 LP1'F) and P453L (p1/p6 PP5'L) CS changes. In population-based sequence analyses the I50V mutant was invariably linked to either L449F or P453L. Clonal analysis revealed that both CS mutations were never present in the same genome. Sequential plasma samples from one patient revealed a transition from I50V M46L P453L viruses at early time points to I50V M46I L449F viruses in later samples. Various combinations of the protease and Gag mutations were introduced into the HXB2 laboratory strain of HIV-1. In both single- and multiple-cycle assay systems and in the context of I50V, the L449F and P453L changes consistently increased the 50% inhibitory concentration of APV, while the CS changes alone had no measurable effect on inhibitor sensitivity. The decreased in vitro fitness of the I50V mutant was only partially improved by addition of either CS change (I50V M46I L449F mutant replicative capacity approximately 16% of that of wild-type virus). Western blot analysis of Pr55 Gag precursor cleavage products from infected-cell cultures indicated accumulation of uncleaved Gag p1-p6 in all I50V viruses without coexisting CS changes. Purified I50V protease catalyzed cleavage of decapeptides incorporating the L449F or P453L change 10-fold and 22-fold more efficiently than cleavage of the wild-type substrate, respectively. HIV-1 protease CS changes are selected during PI therapy and can have effects on both viral fitness and phenotypic resistance to PIs.
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Affiliation(s)
- Michael F Maguire
- Department of Clinical Virology, GlaxoSmithKline Research and Development, Stevenage SG1 2NY, United Kingdom
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Dash C, Rao M. Interactions of a novel inhibitor from an extremophilic Bacillus sp. with HIV-1 protease: implications for the mechanism of inactivation. J Biol Chem 2001; 276:2487-93. [PMID: 11042202 DOI: 10.1074/jbc.m005662200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The active site cleft of the HIV-1 protease (PR) is bound by two identical conformationally mobile loops known as flaps, which are important for substrate binding and catalysis. The present article reports, for the first time, an HIV-1 PR inhibitor, ATBI, from an extremophilic Bacillus sp. The inhibitor is found to be a hydrophilic peptide with Mr of 1147, and an amino acid sequence of Ala-Gly-Lys-Lys-Asp-Asp-Asp-Asp-Pro-Pro-Glu. Sequence homology exhibited no similarity with the reported peptidic inhibitors of HIV-1 PR. Investigation of the kinetics of the enzyme-inhibitor interactions revealed that ATBI is a noncompetitive and tight binding inhibitor with the IC(50) and K(i) values 18.0 and 17.8 nm, respectively. The binding of the inhibitor with the enzyme and the subsequent induction of the localized conformational changes in the flap region of the HIV-1 PR were monitored by exploiting the intrinsic fluorescence of the surface exposed Trp-42 residues, which are present at the proximity of the flaps. We have demonstrated by fluorescence and circular dichroism studies that ATBI binds in the active site of the HIV-1 PR and thereby leads to the inactivation of the enzyme. Based on our results, we propose that the inactivation is due to the reorganization of the flaps impairing its flexibility leading toward inaccessibility of the substrate to the active site of the enzyme.
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Affiliation(s)
- C Dash
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India
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15
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Côté HC, Brumme ZL, Harrigan PR. Human immunodeficiency virus type 1 protease cleavage site mutations associated with protease inhibitor cross-resistance selected by indinavir, ritonavir, and/or saquinavir. J Virol 2001; 75:589-94. [PMID: 11134271 PMCID: PMC113954 DOI: 10.1128/jvi.75.2.589-594.2001] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the prevalence of cleavage site mutations, both within and outside the gag region, in 28 protease inhibitor (PI) cross-resistant patients treated with indinavir, ritonavir, and/or saquinavir compared to control patients treated with reverse transcriptase inhibitors. Three human immunodeficiency virus protease cleavage sites within gag (p2/NC, NC/p1, and NC/TFP) showed considerable in vivo evolution before and after therapy with indinavir, ritonavir, and/or saquinavir. Another gag cleavage site (p1/p6(gag)) showed a trend compared to matched controls. The other eight recognized cleavage sites showed relatively little difference between PI-resistant cases and controls. An A-->V substitution at the P2 position of the NC/p1 and NC/TFP cleavage sites was the most common (29%) change selected by the PIs used in this study.
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Affiliation(s)
- H C Côté
- British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, British Columbia, Canada V6Z 1Y6
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16
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Robinson BS, Riccardi KA, Gong YF, Guo Q, Stock DA, Blair WS, Terry BJ, Deminie CA, Djang F, Colonno RJ, Lin PF. BMS-232632, a highly potent human immunodeficiency virus protease inhibitor that can be used in combination with other available antiretroviral agents. Antimicrob Agents Chemother 2000; 44:2093-9. [PMID: 10898681 PMCID: PMC90019 DOI: 10.1128/aac.44.8.2093-2099.2000] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BMS-232632 is an azapeptide human immunodeficiency virus type 1 (HIV-1) protease (Prt) inhibitor that exhibits potent anti-HIV activity with a 50% effective concentration (EC(50)) of 2.6 to 5.3 nM and an EC(90) of 9 to 15 nM in cell culture. Proof-of-principle studies indicate that BMS-232632 blocks the cleavage of viral precursor proteins in HIV-infected cells, proving that it functions as an HIV Prt inhibitor. Comparative studies showed that BMS-232632 is generally more potent than the five currently approved HIV-1 Prt inhibitors. Furthermore, BMS-232632 is highly selective for HIV-1 Prt and exhibits cytotoxicity only at concentrations 6,500- to 23, 000-fold higher than that required for anti-HIV activity. To assess the potential of this inhibitor when used in combination with other antiretrovirals, BMS-232632 was evaluated for anti-HIV activity in two-drug combination studies. Combinations of BMS-232632 with either stavudine, didanosine, lamivudine, zidovudine, nelfinavir, indinavir, ritonavir, saquinavir, or amprenavir in HIV-infected peripheral blood mononuclear cells yielded additive to moderately synergistic antiviral effects. Importantly, combinations of drug pairs did not result in antagonistic anti-HIV activity or enhanced cytotoxic effects at the highest concentrations used for antiviral evaluation. Our results suggest that BMS-232632 may be an effective HIV-1 inhibitor that may be utilized in a variety of different drug combinations.
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Affiliation(s)
- B S Robinson
- Department of Virology and Non-Clinical Biostatistics, Bristol-Myers Squibb Company, Wallingford, Connecticut 06492, USA
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Short GF, Laikhter AL, Lodder M, Shayo Y, Arslan T, Hecht SM. Probing the S1/S1' substrate binding pocket geometry of HIV-1 protease with modified aspartic acid analogues. Biochemistry 2000; 39:8768-81. [PMID: 10913288 DOI: 10.1021/bi000214t] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aspartates 25 and 125, the active site residues of HIV-1 protease, participate functionally in proteolysis by what is believed to be a general acid-general base mechanism. However, the structural role that these residues may play in the formation and maintenance of the neighboring S1/S1' substrate binding pockets remains largely unstudied. Because the active site aspartic acids are essential for catalysis, alteration of these residues to any other naturally occurring amino acid by conventional site-directed mutagenesis renders the protease inactive, and hence impossible to characterize functionally. To investigate whether Asp-25 and Asp-125 may also play a structural role that influences substrate processing, a series of active site protease mutants has been produced in a cell-free protein synthesizing system via readthrough of mRNA nonsense (UAG) codons by chemically misacylated suppressor tRNAs. The suppressor tRNAs were activated with the unnatural aspartic acid analogues erythro-beta-methylaspartic acid, threo-beta-methylaspartic acid, or beta,beta-dimethylaspartic acid. On the basis of the specific activity measurements of the mutants that were produced, the introduction of the beta-methyl moiety was found to alter protease function to varying extents depending upon its orientation. While a beta-methyl group in the erythro orientation was the least deleterious to the specific activity of the protease, a beta-methyl group in the threo orientation, present in the modified proteins containing threo-beta-methylaspartate and beta,beta-dimethylaspartate, resulted in specific activities between 0 and 45% of that of the wild type depending upon the substrate and the substituted active site position. Titration studies of pH versus specific activity and inactivation studies, using an aspartyl protease specific suicide inhibitor, demonstrated that the mutant proteases maintained bell-shaped pH profiles, as well as suicide-inhibitor susceptibilities that are characteristic of aspartyl proteases. A molecular dynamics simulation of the beta-substituted aspartates in position 25 of HIV-1 protease indicated that the threo-beta-methyl moiety may partially obstruct the adjacent S1' binding pocket, and also cause reorganization within the pocket, especially with regard to residues Val-82 and Ile-84. This finding, in conjunction with the biochemical studies, suggests that the active site aspartate residues are in proximity to the S1/S1' binding pocket and may be spatially influenced by the residues presented in these pockets upon substrate binding. It thus seems possible that the catalytic residues cooperatively interact with the residues that constitute the S1/S1' binding pockets and can be repositioned during substrate binding to orient the active site carboxylates with respect to the scissile amide bond, a process that likely affects the facility of proteolysis.
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Affiliation(s)
- G F Short
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22901, USA
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Abstract
Although the human immunodeficiency virus (HIV) protease inhibitors are highly effective, they are characterized by low and/or variable bioavailability with limited penetration into the central nervous system (CNS). Their clinical use is limited by patient compliance and by drug-drug interactions. The effect of drug solubility on their oral absorption has been investigated but further evaluation of this relationship is required. First pass metabolism appears to be significant for the HIV protease inhibitors and they are extensively metabolized by cytochrome P450 (CYP) 3A4. Recent studies suggest that these drugs are substrates for the P-glycoprotein efflux pump, which can limit their intestinal absorption and their transport across the blood-brain barrier. Drugs inducing or inhibiting CYP3A4 and/or P-glycoprotein may influence the bioavailability of the HIV protease inhibitors. The low bioavailability, variable absorption and drug-drug interactions of the HIV protease inhibitors may be related to the variability of cytochrome P450 and P-glycoprotein expression and to possible CYP3A4/P-glycoprotein interactions. To improve oral HIV protease inhibitor therapy, it is essential to mechanistically characterize the cell specific, tissue specific and regional intestinal dependencies of drug transport, secretory transport, metabolism and P-glycoprotein/CPY3A4 interactions. This report reviews the physicochemical characteristics and pharmacokinetics of the HIV protease inhibitors while considering the relationships between their hepatic and intestinal metabolism, low bioavailability, variable absorption and drug-drug interactions.
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Boden D, Markowitz M. Resistance to human immunodeficiency virus type 1 protease inhibitors. Antimicrob Agents Chemother 1998; 42:2775-83. [PMID: 9797203 PMCID: PMC105943 DOI: 10.1128/aac.42.11.2775] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- D Boden
- Aaron Diamond AIDS Research Center, New York, New York 10016, USA
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20
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Carrillo A, Stewart KD, Sham HL, Norbeck DW, Kohlbrenner WE, Leonard JM, Kempf DJ, Molla A. In vitro selection and characterization of human immunodeficiency virus type 1 variants with increased resistance to ABT-378, a novel protease inhibitor. J Virol 1998; 72:7532-41. [PMID: 9696850 PMCID: PMC109995 DOI: 10.1128/jvi.72.9.7532-7541.1998] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABT-378, a new human immunodeficiency virus type 1 (HIV-1) protease inhibitor which is significantly more active than ritonavir in cell culture, is currently under investigation for the treatment of AIDS. Development of viral resistance to ABT-378 in vitro was studied by serial passage of HIV-1 (pNL4-3) in MT-4 cells. Selection of viral variants with increasing concentrations of ABT-378 revealed a sequential appearance of mutations in the protease gene: I84V-L10F-M46I-T91S-V32I-I47V. Further selection at a 3.0 microM inhibitor concentration resulted in an additional change at residue 47 (V47A), as well as reversion at residue 32 back to the wild-type sequence. The 50% effective concentration of ABT-378 against passaged virus containing these additional changes was 338-fold higher than that against wild-type virus. In addition to changes in the protease gene, sequence analysis of passaged virus revealed mutations in the p1/p6 (P1' residue Leu to Phe) and p7/p1 (P2 residue Ala to Val) gag proteolytic processing sites. The p1/p6 mutation appeared in several clones derived from early passages and was present in all clones obtained from passage P11 (0.42 microM ABT-378) onward. The p7/p1 mutation appeared very late during the selection process and was strongly associated with the emergence of the additional change at residue 47 (V47A) and the reversion at residue 32 back to the wild-type sequence. Furthermore, this p7/p1 mutation was present in all clones obtained from passage P17 (3.0 microM ABT-378) onward and always occurred in conjunction with the p1/p6 mutation. Full-length molecular clones containing protease mutations observed very late during the selection process were constructed and found to be viable only in the presence of both the p7/p1 and p1/p6 cleavage-site mutations. This suggests that mutation of these gag proteolytic cleavage sites is required for the growth of highly resistant HIV-1 selected by ABT-378 and supports recent work demonstrating that mutations in the p7/p1/p6 region play an important role in conferring resistance to protease inhibitors (L. Doyon et al., J. Virol. 70:3763-3769, 1996; Y. M. Zhang et al., J. Virol. 71:6662-6670, 1997).
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Affiliation(s)
- A Carrillo
- Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, Illinois 60064, USA.
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21
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Shao W, Everitt L, Manchester M, Loeb DD, Hutchison CA, Swanstrom R. Sequence requirements of the HIV-1 protease flap region determined by saturation mutagenesis and kinetic analysis of flap mutants. Proc Natl Acad Sci U S A 1997; 94:2243-8. [PMID: 9122179 PMCID: PMC20072 DOI: 10.1073/pnas.94.6.2243] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/24/1996] [Indexed: 02/04/2023] Open
Abstract
The retroviral proteases (PRs) have a structural feature called the flap, which consists of a short anti-parallel beta-sheet with a turn. The flap extends over the substrate binding cleft and must be flexible to allow entry and exit of the polypeptide substrates and products. We analyzed the sequence requirements of the amino acids within the flap region (positions 46-56) of the HIV-1 PR. The phenotypes of 131 substitution mutants were determined using a bacterial expression system. Four of the mutant PRs with mutations in different regions of the flap were selected for kinetic analysis. Our phenotypic analysis, considered in the context of published structures of the HIV-1 PR with a bound substrate analogs, shows that: (i) Met-46 and Phe-53 participate in hydrophobic interactions on the solvent-exposed face of the flap; (ii) Ile-47, Ile-54, and Val-56 participate in hydrophobic interactions on the inner face of the flap; (iii) Ile-50 has hydrophobic interactions at the distance of both the delta and gamma carbons; (iv) the three glycine residues in the beta-turn of the flap are virtually intolerant of substitutions. Among these mutant PRs, we have identified changes in both kcat and Km. These results establish the nature of the side chain requirements at each position in the flap and document a role for the flap in both substrate binding and catalysis.
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Affiliation(s)
- W Shao
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 27599, USA
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Böhm HJ, Klebe G. Was läßt sich aus der molekularen Erkennung in Protein-Ligand-Komplexen für das Design neuer Wirkstoffe lernen? Angew Chem Int Ed Engl 1996. [DOI: 10.1002/ange.19961082205] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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23
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Martin JA, Redshaw S, Thomas GJ. Inhibitors of HIV proteinase. PROGRESS IN MEDICINAL CHEMISTRY 1995; 32:239-87. [PMID: 8577919 DOI: 10.1016/s0079-6468(08)70455-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- J A Martin
- Roche Products Ltd., Welwyn Garden City, Herts, UK
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Abstract
The HIV-1 protease is becoming one of the most important proteins in medicine. It is perhaps the most attractive target for development of an anti-HIV-1 therapeutic drug. Given its pre-eminent position in biomedical research, many aspects of the protease are currently coming under close scrutiny. Protease is available from recombinant sources, and numerous structures of the enzyme (with and without bound inhibitors) have now been determined by crystallographic methods, enabling the full utilization of mutational analysis in the study of protease function. In addition, the selection of HIV-1 mutants with reduced sensitivity to protease inhibitors is further complementing research on this enzyme.
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Affiliation(s)
- R Swanstrom
- Department of Biochemistry and Biophysics, UNC Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill 27599-7295
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25
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Identification of temperature-sensitive mutants of the human immunodeficiency virus type 1 protease through saturation mutagenesis. Amino acid side chain requirements for temperature sensitivity. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37342-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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26
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Chapter 14. HIV Protease Inhibitors. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1994. [DOI: 10.1016/s0065-7743(08)60727-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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