1
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Structural Insights on Retroviral DNA Integration: Learning from Foamy Viruses. Viruses 2019; 11:v11090770. [PMID: 31443391 PMCID: PMC6784120 DOI: 10.3390/v11090770] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 12/28/2022] Open
Abstract
Foamy viruses (FV) are retroviruses belonging to the Spumaretrovirinae subfamily. They are non-pathogenic viruses endemic in several mammalian hosts like non-human primates, felines, bovines, and equines. Retroviral DNA integration is a mandatory step and constitutes a prime target for antiretroviral therapy. This activity, conserved among retroviruses and long terminal repeat (LTR) retrotransposons, involves a viral nucleoprotein complex called intasome. In the last decade, a plethora of structural insights on retroviral DNA integration arose from the study of FV. Here, we review the biochemistry and the structural features of the FV integration apparatus and will also discuss the mechanism of action of strand transfer inhibitors.
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2
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Park JH, Yun JH, Shi Y, Han J, Li X, Jin Z, Kim T, Park J, Park S, Liu H, Lee W. Non-Cryogenic Structure and Dynamics of HIV-1 Integrase Catalytic Core Domain by X-ray Free-Electron Lasers. Int J Mol Sci 2019; 20:E1943. [PMID: 31010024 PMCID: PMC6514806 DOI: 10.3390/ijms20081943] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/17/2019] [Accepted: 04/19/2019] [Indexed: 12/22/2022] Open
Abstract
HIV-1 integrase (HIV-1 IN) is an enzyme produced by the HIV-1 virus that integrates genetic material of the virus into the DNA of infected human cells. HIV-1 IN acts as a key component of the Retroviral Pre-Integration Complex (PIC). Protein dynamics could play an important role during the catalysis of HIV-1 IN; however, this process has not yet been fully elucidated. X-ray free electron laser (XFEL) together with nuclear magnetic resonance (NMR) could provide information regarding the dynamics during this catalysis reaction. Here, we report the non-cryogenic crystal structure of HIV-1 IN catalytic core domain at 2.5 Å using microcrystals in XFELs. Compared to the cryogenic structure at 2.1 Å using conventional synchrotron crystallography, there was a good agreement between the two structures, except for a catalytic triad formed by Asp64, Asp116, and Glu152 (DDE) and the lens epithelium-derived growth factor binding sites. The helix III region of the 140-153 residues near the active site and the DDE triad show a higher dynamic profile in the non-cryogenic structure, which is comparable to dynamics data obtained from NMR spectroscopy in solution state.
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Affiliation(s)
- Jae-Hyun Park
- Structural Biochemistry & Molecular Biophysics Laboratory, Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea.
| | - Ji-Hye Yun
- Structural Biochemistry & Molecular Biophysics Laboratory, Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea.
| | - Yingchen Shi
- Complex Systems Division, Beijing Computational Science Research Center, Beijing 100193, China.
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
| | - Jeongmin Han
- Structural Biochemistry & Molecular Biophysics Laboratory, Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea.
| | - Xuanxuan Li
- Complex Systems Division, Beijing Computational Science Research Center, Beijing 100193, China.
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
| | - Zeyu Jin
- Structural Biochemistry & Molecular Biophysics Laboratory, Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea.
| | - Taehee Kim
- Structural Biochemistry & Molecular Biophysics Laboratory, Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea.
| | - Jaehyun Park
- Pohang Accelerator Laboratory, Pohang 37673, Korea.
| | - Sehan Park
- Pohang Accelerator Laboratory, Pohang 37673, Korea.
| | - Haiguang Liu
- Complex Systems Division, Beijing Computational Science Research Center, Beijing 100193, China.
| | - Weontae Lee
- Structural Biochemistry & Molecular Biophysics Laboratory, Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea.
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3
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Singer CM, Joy D, Jacobs DJ, Nesmelova IV. Rigidity and flexibility characteristics of DD[E/D]-transposases Mos1 and Sleeping Beauty. Proteins 2018; 87:313-325. [PMID: 30582767 DOI: 10.1002/prot.25653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 12/06/2018] [Accepted: 12/19/2018] [Indexed: 11/05/2022]
Abstract
DD[E/D]-transposases catalyze the multistep reaction of cut-and-paste DNA transposition. Structurally, several DD[E/D]-transposases have been characterized, revealing a multi-domain structure with the catalytic domain possessing the RNase H-like structural motif that brings three catalytic residues (D, D, and E or D) into close proximity for the catalysis. However, the dynamic behavior of DD[E/D]-transposases during transposition remains poorly understood. Here, we analyze the rigidity and flexibility characteristics of two representative DD[E/D]-transposases Mos1 and Sleeping Beauty (SB) using the minimal distance constraint model (mDCM). We find that the catalytic domain of both transposases is globally rigid, with the notable exception of the clamp loop being flexible in the DNA-unbound form. Within this globally rigid structure, the central β-sheet of the RNase H-like motif is much less rigid in comparison to its surrounding α-helices, forming a cage-like structure. The comparison of the original SB transposase to its hyperactive version SB100X reveals the region where the change in flexibility/rigidity correlates with increased activity. This region is found to be within the RNase H-like structural motif and comprise the loop leading from beta-strand B3 to helix H1, helices H1 and H2, which are located on the same side of the central beta-sheet, and the loop between helix H3 and beta-strand B5. We further identify the RKEN214-217DAVQ mutations of the set of hyperactive mutations within the catalytic domain of SB transposase to be the driving factor that induces change in residue-pair rigidity correlations within SB transposase. Given that a signature RNase H-like structural motif is found in DD[E/D]-transposases and, more broadly, in a large superfamily of polynucleotidyl transferases, our results are relevant to these proteins as well.
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Affiliation(s)
- Christopher M Singer
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina
| | - Diana Joy
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina
| | - Donald J Jacobs
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina.,Center for Biomedical Engineering, University of North Carolina, Charlotte, North Carolina
| | - Irina V Nesmelova
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina.,Center for Biomedical Engineering, University of North Carolina, Charlotte, North Carolina
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4
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Wagstaff KM, Headey S, Telwatte S, Tyssen D, Hearps AC, Thomas DR, Tachedjian G, Jans DA. Molecular dissection of an inhibitor targeting the HIV integrase dependent preintegration complex nuclear import. Cell Microbiol 2018; 21:e12953. [PMID: 30216959 PMCID: PMC6585680 DOI: 10.1111/cmi.12953] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 08/26/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022]
Abstract
Human immunodeficiency virus (HIV) continues to be a major contributor to morbidity and mortality worldwide, particularly in developing nations where high cost and logistical issues severely limit the use of current HIV therapeutics. This, combined HIV's high propensity to develop resistance, means that new antiviral agents against novel targets are still urgently required. We previously identified novel anti-HIV agents directed against the nuclear import of the HIV integrase (IN) protein, which plays critical roles in the HIV lifecycle inside the cell nucleus, as well as in transporting the HIV preintegration complex (PIC) into the nucleus. Here we investigate the structure activity relationship of a series of these compounds for the first time, including a newly identified anti-IN compound, budesonide, showing that the extent of binding to the IN core domain correlates directly with the ability of the compound to inhibit IN nuclear transport in a permeabilised cell system. Importantly, compounds that inhibited the nuclear transport of IN were found to significantly decrease HIV viral replication, even in a dividing cell system. Significantly, budesonide or its analogue flunisolide, were able to effect a significant reduction in the presence of specific nuclear forms of the HIV DNA (2-LTR circles), suggesting that the inhibitors work though blocking IN, and potentially PIC, nuclear import. The work presented here represents a platform for further development of these specific inhibitors of HIV replication with therapeutic and prophylactic potential.
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Affiliation(s)
- Kylie M Wagstaff
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Stephen Headey
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Parkville, Australia
| | | | - David Tyssen
- Life Science Division, Burnet Institute, Melbourne, Australia
| | - Anna C Hearps
- Life Science Division, Burnet Institute, Melbourne, Australia.,Department of Infectious Diseases, Melbourne University, Melbourne, Australia
| | - David R Thomas
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | | | - David A Jans
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
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5
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Northfield SE, Wielens J, Headey SJ, Williams-Noonan BJ, Mulcair M, Scanlon MJ, Parker MW, Thompson PE, Chalmers DK. Cyclic Hexapeptide Mimics of the LEDGF Integrase Recognition Loop in Complex with HIV-1 Integrase. ChemMedChem 2018; 13:1555-1565. [PMID: 29862651 DOI: 10.1002/cmdc.201800129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/21/2018] [Indexed: 12/18/2022]
Abstract
The p75 splice variant of lens epithelium-derived growth factor (LEDGF) is a 75 kDa protein, which is recruited by the human immunodeficiency virus (HIV) to tether the pre-integration complex to the host chromatin and promote integration of proviral DNA into the host genome. We designed a series of small cyclic peptides that are structural mimics of the LEDGF binding domain, which interact with integrase as potential binding inhibitors. Herein we present the X-ray crystal structures, NMR studies, SPR analysis, and conformational studies of four cyclic peptides bound to the HIV-1 integrase core domain. Although the X-ray studies show that the peptides closely mimic the LEDGF binding loop, the measured affinities of the peptides are in the low millimolar range. Computational analysis using conformational searching and free energy calculations suggest that the low affinity of the peptides is due to mismatch between the low-energy solution and bound conformations.
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Affiliation(s)
- Susan E Northfield
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Jerome Wielens
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia.,ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria, 3065, Australia
| | - Stephen J Headey
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Billy J Williams-Noonan
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Mark Mulcair
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Michael W Parker
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria, 3065, Australia.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Philip E Thompson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia
| | - David K Chalmers
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria, 3052, Australia
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6
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Ammar FF, Hobaika Z, Abdel-Azeim S, Zargarian L, Maroun RG, Fermandjian S. A targeted DNA substrate mechanism for the inhibition of HIV-1 integrase by inhibitors with antiretroviral activity. FEBS Open Bio 2016; 6:234-50. [PMID: 27239438 PMCID: PMC4821353 DOI: 10.1002/2211-5463.12025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/25/2015] [Accepted: 12/16/2015] [Indexed: 12/21/2022] Open
Abstract
We recently reported that viral DNA could be the primary target of raltegravir (RAL), an efficient anti‐HIV‐1 drug, which acts by inhibiting integrase. To elucidate this mechanism, we conducted a comparative analysis of RAL and TB11, a diketoacid abandoned as an anti‐HIV‐1 drug for its weak efficiency and marked toxicity, and tested the effects of the catalytic cofactor Mg2+ (5 mm) on drug‐binding properties. We used circular dichroism and fluorescence to determine drug affinities for viral DNA long terminal repeats (LTRs) and peptides derived from the integrase active site and DNA retardation assays to assess drug intercalation into DNA base pairs. We found that RAL bound more tightly to LTR ends than did TB11 (a diketo acid bearing an azido group) and that Mg2+ significantly increased the affinity of both RAL and TB11. We also observed a good relationship between drug binding with processed LTR and strand transfer inhibition. This unusual type of inhibition was caused by Mg2+‐assisted binding of drugs to DNA substrate, rather than to enzyme. Notably, while RAL bound exclusively to the cleavable/cleaved site, TB11 further intercalated into DNA base pairs and interacted with the integrase‐derived peptides. These unwanted binding sites explain the weaker bioavailability and higher toxicity of TB11 compared with the more effective RAL.
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Affiliation(s)
- Farah F Ammar
- Centre d'Analyses et de Recherche UR EGFEM Faculté des Sciences Université Saint-Joseph Beirut Lebanon; LBPA, UMR8113 du CNRS Ecole Normale Supérieure de Cachan Cedex Cachan France
| | - Zeina Hobaika
- Centre d'Analyses et de Recherche UR EGFEM Faculté des Sciences Université Saint-Joseph Beirut Lebanon
| | - Safwat Abdel-Azeim
- LBPA, UMR8113 du CNRS Ecole Normale Supérieure de Cachan Cedex Cachan France
| | - Loussinée Zargarian
- LBPA, UMR8113 du CNRS Ecole Normale Supérieure de Cachan Cedex Cachan France
| | - Richard G Maroun
- Centre d'Analyses et de Recherche UR EGFEM Faculté des Sciences Université Saint-Joseph Beirut Lebanon
| | - Serge Fermandjian
- LBPA, UMR8113 du CNRS Ecole Normale Supérieure de Cachan Cedex Cachan France; Chemistry and Biology, Nucleo(s)tides and Immunology for Therapy UMR8601 CNRS Paris Cedex 06 France
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7
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Production of unstable proteins through the formation of stable core complexes. Nat Commun 2016; 7:10932. [PMID: 26983699 PMCID: PMC4800440 DOI: 10.1038/ncomms10932] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 02/02/2016] [Indexed: 11/30/2022] Open
Abstract
Purification of proteins that participate in large transient complexes is impeded by low amounts, heterogeneity, instability and poor solubility. To circumvent these difficulties we set up a methodology that enables the production of stable complexes for structural and functional studies. This procedure is benchmarked and applied to two challenging protein families: the human steroid nuclear receptors (SNR) and the HIV-1 pre-integration complex. In the context of transcriptional regulation studies, we produce and characterize the ligand-binding domains of the glucocorticoid nuclear receptor and the oestrogen receptor beta in complex with a TIF2 (transcriptional intermediary factor 2) domain containing the three SNR-binding motifs. In the context of retroviral integration, we demonstrate the stabilization of the HIV-1 integrase by formation of complexes with partner proteins and DNA. This procedure provides a powerful research tool for structural and functional studies of proteins participating in non-covalent macromolecular complexes. Flexible or disordered domains often hinder the purification of proteins involved in functional interactions. Here the authors describe an approach that enables the production of stable and functional complexes of otherwise unstable proteins in quantities sufficient for structural and functional studies.
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8
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Janowska MK, Wu KP, Baum J. Unveiling transient protein-protein interactions that modulate inhibition of alpha-synuclein aggregation by beta-synuclein, a pre-synaptic protein that co-localizes with alpha-synuclein. Sci Rep 2015; 5:15164. [PMID: 26477939 PMCID: PMC4609965 DOI: 10.1038/srep15164] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 09/11/2015] [Indexed: 01/18/2023] Open
Abstract
Pathology in Parkinson’s disease is linked to self-association of α-Synuclein (αS) into pathogenic oligomeric species and highly ordered amyloid fibrils. Developing effective therapeutic strategies against this debilitating disease is critical and βS, a pre-synaptic protein that co-localizes with αS, can act as an inhibitor of αS assembly. Despite the potential importance of βS as an inhibitor of αS, the nature, location and specificity of the molecular interactions between these two proteins is unknown. Here we use NMR paramagnetic relaxation enhancement experiments, to demonstrate that βS interacts directly with αS in a transient dimer complex with high specificity and weak affinity. Inhibition of αS by βS arises from transient αS/βS heterodimer species that exist primarily in head- to- tail configurations while αS aggregation arises from a more heterogeneous and weaker range of transient interactions that include both head-to-head and head-to-tail configurations. Our results highlight that intrinsically disordered proteins can interact directly with one another at low affinity and that the transient interactions that drive inhibition versus aggregation are distinct by virtue of their plasticity and specificity.
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Affiliation(s)
- Maria K Janowska
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
| | - Kuen-Phon Wu
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
| | - Jean Baum
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
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9
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Nettles WL, Song H, Farquhar ER, Fitzkee NC, Emerson JP. Characterization of the Copper(II) Binding Sites in Human Carbonic Anhydrase II. Inorg Chem 2015; 54:5671-80. [PMID: 26010488 PMCID: PMC4482258 DOI: 10.1021/acs.inorgchem.5b00057] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Human carbonic anhydrase (CA) is a well-studied, robust, mononuclear Zn-containing metalloprotein that serves as an excellent biological ligand system to study the thermodynamics associated with metal ion coordination chemistry in aqueous solution. The apo form of human carbonic anhydrase II (CA) binds 2 equiv of copper(II) with high affinity. The Cu(2+) ions bind independently forming two noncoupled type II copper centers in CA (CuA and CuB). However, the location and coordination mode of the CuA site in solution is unclear, compared to the CuB site that has been well-characterized. Using paramagnetic NMR techniques and X-ray absorption spectroscopy we identified an N-terminal Cu(2+) binding location and collected information on the coordination mode of the CuA site in CA, which is consistent with a four- to five-coordinate N-terminal Cu(2+) binding site reminiscent to a number of N-terminal copper(II) binding sites including the copper(II)-amino terminal Cu(2+) and Ni(2+) and copper(II)-β-amyloid complexes. Additionally, we report a more detailed analysis of the thermodynamics associated with copper(II) binding to CA. Although we are still unable to fully deconvolute Cu(2+) binding data to the high-affinity CuA site, we derived pH- and buffer-independent values for the thermodynamics parameters K and ΔH associated with Cu(2+) binding to the CuB site of CA to be 2 × 10(9) and -17.4 kcal/mol, respectively.
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Affiliation(s)
- Whitnee L. Nettles
- Mississippi State University: Department of Chemistry Box 9573 Mississippi State University Mississippi State, MS 39762-9573
| | - He Song
- Mississippi State University: Department of Chemistry Box 9573 Mississippi State University Mississippi State, MS 39762-9573
| | - Erik R. Farquhar
- Case Western Reserve University Center for Synchrotron Biosciences, National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Nicholas C. Fitzkee
- Mississippi State University: Department of Chemistry Box 9573 Mississippi State University Mississippi State, MS 39762-9573
| | - Joseph P. Emerson
- Mississippi State University: Department of Chemistry Box 9573 Mississippi State University Mississippi State, MS 39762-9573
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10
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Wolkowicz U, Morris ER, Robson M, Trubitsyna M, Richardson JM. Structural basis of Mos1 transposase inhibition by the anti-retroviral drug Raltegravir. ACS Chem Biol 2014; 9:743-51. [PMID: 24397848 PMCID: PMC3977574 DOI: 10.1021/cb400791u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/07/2014] [Indexed: 11/28/2022]
Abstract
DNA transposases catalyze the movement of transposons around genomes by a cut-and-paste mechanism related to retroviral integration. Transposases and retroviral integrases share a common RNaseH-like domain with a catalytic DDE/D triad that coordinates the divalent cations required for DNA cleavage and integration. The anti-retroviral drugs Raltegravir and Elvitegravir inhibit integrases by displacing viral DNA ends from the catalytic metal ions. We demonstrate that Raltegravir, but not Elvitegravir, binds to Mos1 transposase in the presence of Mg(2+) or Mn(2+), without the requirement for transposon DNA, and inhibits transposon cleavage and DNA integration in biochemical assays. Crystal structures at 1.7 Å resolution show Raltegravir, in common with integrases, coordinating two Mg(2+) or Mn(2+) ions in the Mos1 active site. However, in the absence of transposon ends, the drug adopts an unusual, compact binding mode distinct from that observed in the active site of the prototype foamy virus integrase.
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Affiliation(s)
- Urszula
M. Wolkowicz
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Elizabeth R. Morris
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Michael Robson
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Maryia Trubitsyna
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Julia M. Richardson
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
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11
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Maillot B, Lévy N, Eiler S, Crucifix C, Granger F, Richert L, Didier P, Godet J, Pradeau-Aubreton K, Emiliani S, Nazabal A, Lesbats P, Parissi V, Mely Y, Moras D, Schultz P, Ruff M. Structural and functional role of INI1 and LEDGF in the HIV-1 preintegration complex. PLoS One 2013; 8:e60734. [PMID: 23593299 PMCID: PMC3623958 DOI: 10.1371/journal.pone.0060734] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 03/01/2013] [Indexed: 02/07/2023] Open
Abstract
Integration of the HIV-1 cDNA into the human genome is catalyzed by the viral integrase (IN) protein. Several studies have shown the importance of cellular cofactors that interact with integrase and affect viral integration and infectivity. In this study, we produced a stable complex between HIV-1 integrase, viral U5 DNA, the cellular cofactor LEDGF/p75 and the integrase binding domain of INI1 (INI1-IBD), a subunit of the SWI/SNF chromatin remodeling factor. The stoichiometry of the IN/LEDGF/INI1-IBD/DNA complex components was found to be 4/2/2/2 by mass spectrometry and Fluorescence Correlation Spectroscopy. Functional assays showed that INI1-IBD inhibits the 3′ processing reaction but does not interfere with specific viral DNA binding. Integration assays demonstrate that INI1-IBD decreases the amount of integration events but inhibits by-product formation such as donor/donor or linear full site integration molecules. Cryo-electron microscopy locates INI1-IBD within the cellular DNA binding site of the IN/LEDGF complex, constraining the highly flexible integrase in a stable conformation. Taken together, our results suggest that INI1 could stabilize the PIC in the host cell, by maintaining integrase in a stable constrained conformation which prevents non-specific interactions and auto integration on the route to its integration site within nucleosomes, while LEDGF organizes and stabilizes an active integrase tetramer suitable for specific vDNA integration. Moreover, our results provide the basis for a novel type of integrase inhibitor (conformational inhibitor) representing a potential new strategy for use in human therapy.
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Affiliation(s)
- Benoit Maillot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Nicolas Lévy
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Sylvia Eiler
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Corinne Crucifix
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Florence Granger
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Ludovic Richert
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, UDS, Faculté de Pharmacie, Illkirch, France
| | - Pascal Didier
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, UDS, Faculté de Pharmacie, Illkirch, France
| | - Julien Godet
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, UDS, Faculté de Pharmacie, Illkirch, France
| | - Karine Pradeau-Aubreton
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Stéphane Emiliani
- Institut Cochin, Université Paris Descartes, CNRS (UMR8104), INSERM (U567), Paris, France
| | | | - Paul Lesbats
- Laboratoire de Microbiologie Fondamentale et Pathogénicité, CNRS (UMR5234), Université de Bordeaux 2, Bordeaux, France
| | - Vincent Parissi
- Laboratoire de Microbiologie Fondamentale et Pathogénicité, CNRS (UMR5234), Université de Bordeaux 2, Bordeaux, France
| | - Yves Mely
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, UDS, Faculté de Pharmacie, Illkirch, France
| | - Dino Moras
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Patrick Schultz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
| | - Marc Ruff
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Biologie Structurale intégrative, Université de Strasbourg, U596 INSERM, UMR7104 CNRS, Illkirch, France
- * E-mail:
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12
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Abstract
Though lacking a well-defined three-dimensional structure, intrinsically unstructured proteins are ubiquitous in nature. These molecules play crucial roles in many cellular processes, especially signaling and regulation. Surprisingly, even enzyme catalysis can tolerate substantial disorder. This observation contravenes conventional wisdom but is relevant to an understanding of how protein dynamics modulates enzyme function. This chapter reviews properties and characteristics of disordered proteins, emphasizing examples of enzymes that lack defined structures, and considers implications of structural disorder for catalytic efficiency and evolution.
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13
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Serrao E, Thys W, Demeulemeester J, Al-Mawsawi LQ, Christ F, Debyser Z, Neamati N. A symmetric region of the HIV-1 integrase dimerization interface is essential for viral replication. PLoS One 2012; 7:e45177. [PMID: 23028829 PMCID: PMC3445459 DOI: 10.1371/journal.pone.0045177] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/17/2012] [Indexed: 01/06/2023] Open
Abstract
HIV-1 integrase (IN) is an important target for contemporary antiretroviral drug design research. Historically, efforts at inactivating the enzyme have focused upon blocking its active site. However, it has become apparent that new classes of allosteric inhibitors will be necessary to advance the antiretroviral field in light of the emergence of viral strains resistant to contemporary clinically used IN drugs. In this study we have characterized the importance of a close network of IN residues, distant from the active site, as important for the obligatory multimerization of the enzyme and viral replication as a whole. Specifically, we have determined that the configuration of six residues within a highly symmetrical region at the IN dimerization interface, composed of a four-tiered aromatic interaction flanked by two salt bridges, significantly contributes to proper HIV-1 replication. Additionally, we have utilized a quantitative luminescence assay to examine IN oligomerization and have determined that there is a very low tolerance for amino acid substitutions along this region. Even conservative residue substitutions negatively impacted IN multimerization, resulting in an inactive viral enzyme and a non-replicative virus. We have shown that there is a very low tolerance for amino acid variation at the symmetrical dimeric interface region characterized in this study, and therefore drugs designed to target the amino acid network detailed here could be expected to yield a significantly reduced number of drug-resistant escape mutations compared to contemporary clinically-evaluated antiretrovirals.
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Affiliation(s)
- Erik Serrao
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California, United States of America
| | - Wannes Thys
- Laboratory for Molecular Virology and Gene Therapy, Division of Molecular Medicine, Katholieke Universiteit Leuven, Flanders, Belgium
| | - Jonas Demeulemeester
- Laboratory for Molecular Virology and Gene Therapy, Division of Molecular Medicine, Katholieke Universiteit Leuven, Flanders, Belgium
| | - Laith Q. Al-Mawsawi
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California, United States of America
| | - Frauke Christ
- Laboratory for Molecular Virology and Gene Therapy, Division of Molecular Medicine, Katholieke Universiteit Leuven, Flanders, Belgium
| | - Zeger Debyser
- Laboratory for Molecular Virology and Gene Therapy, Division of Molecular Medicine, Katholieke Universiteit Leuven, Flanders, Belgium
| | - Nouri Neamati
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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14
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Abstract
Integrase (IN) is a clinically validated target for the treatment of human immunodeficiency virus infections and raltegravir exhibits remarkable clinical activity. The next most advanced IN inhibitor is elvitegravir. However, mutant viruses lead to treatment failure and mutations within the IN coding sequence appear to confer cross-resistance. The characterization of those mutations is critical for the development of second generation IN inhibitors to overcome resistance. This review focuses on IN resistance based on structural and biochemical data, and on the role of the IN flexible loop i.e., between residues G140-G149 in drug action and resistance.
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Affiliation(s)
| | | | | | - Yves Pommier
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-301-496-5944; Fax: +1-301-402-0752
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15
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Ammar FF, Abdel-Azeim S, Zargarian L, Hobaika Z, Maroun RG, Fermandjian S. Unprocessed viral DNA could be the primary target of the HIV-1 integrase inhibitor raltegravir. PLoS One 2012; 7:e40223. [PMID: 22768342 PMCID: PMC3388078 DOI: 10.1371/journal.pone.0040223] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 06/02/2012] [Indexed: 12/18/2022] Open
Abstract
Integration of HIV DNA into host chromosome requires a 3'-processing (3'-P) and a strand transfer (ST) reactions catalyzed by virus integrase (IN). Raltegravir (RAL), commonly used in AIDS therapy, belongs to the family of IN ST inhibitors (INSTIs) acting on IN-viral DNA complexes (intasomes). However, studies show that RAL fails to bind IN alone, but nothing has been reported on the behaviour of RAL toward free viral DNA. Here, we assessed whether free viral DNA could be a primary target for RAL, assuming that the DNA molecule is a receptor for a huge number of pharmacological agents. Optical spectroscopy, molecular dynamics and free energy calculations, showed that RAL is a tight binder of both processed and unprocessed LTR (long terminal repeat) ends. Complex formation involved mainly van der Waals forces and was enthalpy driven. Dissociation constants (Kds) revealed that RAL affinity for unbound LTRs was stronger than for bound LTRs. Moreover, Kd value for binding of RAL to LTRs and IC50 value (half concentration for inhibition) were in same range, suggesting that RAL binding to DNA and ST inhibition are correlated events. Accommodation of RAL into terminal base-pairs of unprocessed LTR is facilitated by an extensive end fraying that lowers the RAL binding energy barrier. The RAL binding entails a weak damping of fraying and correlatively of 3'-P inhibition. Noteworthy, present calculated RAL structures bound to free viral DNA resemble those found in RAL-intasome crystals, especially concerning the contacts between the fluorobenzyl group and the conserved 5'C(4)pA(3)3' step. We propose that RAL inhibits IN, in binding first unprocessed DNA. Similarly to anticancer drug poisons acting on topoisomerases, its interaction with DNA does not alter the cut, but blocks the subsequent joining reaction. We also speculate that INSTIs having viral DNA rather IN as main target could induce less resistance.
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Affiliation(s)
- Farah F. Ammar
- LBPA, UMR8113 du CNRS, Ecole Normale Supérieure de Cachan, Cedex, Cachan, France
- Unité de Biochimie, Département SVT, Faculté des Sciences, Université Saint-Joseph, CST-Mar Roukoz, Beyrouth, Liban
| | - Safwat Abdel-Azeim
- LBPA, UMR8113 du CNRS, Ecole Normale Supérieure de Cachan, Cedex, Cachan, France
| | - Loussinée Zargarian
- LBPA, UMR8113 du CNRS, Ecole Normale Supérieure de Cachan, Cedex, Cachan, France
| | - Zeina Hobaika
- Unité de Biochimie, Département SVT, Faculté des Sciences, Université Saint-Joseph, CST-Mar Roukoz, Beyrouth, Liban
| | - Richard G. Maroun
- Unité de Biochimie, Département SVT, Faculté des Sciences, Université Saint-Joseph, CST-Mar Roukoz, Beyrouth, Liban
| | - Serge Fermandjian
- LBPA, UMR8113 du CNRS, Ecole Normale Supérieure de Cachan, Cedex, Cachan, France
- * E-mail:
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16
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Huang M, Grant GH, Richards WG. Binding modes of diketo-acid inhibitors of HIV-1 integrase: a comparative molecular dynamics simulation study. J Mol Graph Model 2011; 29:956-64. [PMID: 21531158 PMCID: PMC3101338 DOI: 10.1016/j.jmgm.2011.04.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/30/2011] [Accepted: 04/01/2011] [Indexed: 11/18/2022]
Abstract
HIV-1 integrase (IN) has become an attractive target since drug resistance against HIV-1 reverse transcriptase (RT) and protease (PR) has appeared. Diketo acid (DKA) inhibitors are potent and selective inhibitors of HIV-1 IN: however the action mechanism is not well understood. Here, to study the inhibition mechanism of DKAs we performed 10 ns comparative molecular dynamics simulations on HIV-1 IN bound with three most representative DKA inhibitors: Shionogi inhibitor, S-1360 and two Merck inhibitors L-731,988 and L-708,906. Our simulations show that the acidic part of S-1360 formed salt bridge and cation-π interactions with Lys159. In addition, the catalytic Glu152 in S-1360 was pushed away from the active site to form an ion-pair interaction with Arg199. The Merck inhibitors can maintain either one or both of these ion-pair interaction features. The difference in potencies of the DKA inhibitors is thus attributed to the different binding modes at the catalytic site. Such structural information at atomic level, not only demonstrates the action modes of DKA inhibitors but also provides a novel starting point for structural-based design of HIV-1 IN inhibitors.
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Affiliation(s)
- Meilan Huang
- School of Chemistry and Chemical Engineering, David Keir Building, Queens University Belfast, Stranmillis Road, Belfast BT95AG, UK.
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17
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Abstract
OBJECTIVE In this study, we characterized elvitegravir activity in the context of raltegravir resistance mutations. DESIGN Using site-directed mutagenesis, we generated recombinant integrase proteins and viruses harboring raltegravir resistance mutation to assess the biochemical and cellular activity of elvitegravir in the presence of such mutants. METHODS Recombinant proteins were used in gel-based assays. Antiviral data were obtained with reporter viruses in a single-round infection using a luciferase-based assay. RESULTS Although main raltegravir resistance pathways involving mutations at integrase position 148 and 155 confer cross-resistance to elvitegravir, elvitegravir remains fully active against the Y143R mutant integrase and virus particles. CONCLUSION In addition to favorable pharmacokinetics compared to raltegravir, our findings provide the rationale for using elvitegravir in patients failing raltegravir because of the integrase mutation Y143.
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18
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Sgourakis NG, Lange OF, DiMaio F, André I, Fitzkee NC, Rossi P, Montelione GT, Bax A, Baker D. Determination of the structures of symmetric protein oligomers from NMR chemical shifts and residual dipolar couplings. J Am Chem Soc 2011; 133:6288-98. [PMID: 21466200 PMCID: PMC3080108 DOI: 10.1021/ja111318m] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Symmetric protein dimers, trimers, and higher-order cyclic oligomers play key roles in many biological processes. However, structural studies of oligomeric systems by solution NMR can be difficult due to slow tumbling of the system and the difficulty in identifying NOE interactions across protein interfaces. Here, we present an automated method (RosettaOligomers) for determining the solution structures of oligomeric systems using only chemical shifts, sparse NOEs, and domain orientation restraints from residual dipolar couplings (RDCs) without a need for a previously determined structure of the monomeric subunit. The method integrates previously developed Rosetta protocols for solving the structures of monomeric proteins using sparse NMR data and for predicting the structures of both nonintertwined and intertwined symmetric oligomers. We illustrated the performance of the method using a benchmark set of nine protein dimers, one trimer, and one tetramer with available experimental data and various interface topologies. The final converged structures are found to be in good agreement with both experimental data and previously published high-resolution structures. The new approach is more readily applicable to large oligomeric systems than conventional structure-determination protocols, which often require a large number of NOEs, and will likely become increasingly relevant as more high-molecular weight systems are studied by NMR.
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Affiliation(s)
- Nikolaos G Sgourakis
- Department of Biochemistry, University of Washington, Seattle, Washington 98195-7350, USA
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Rhodes DI, Peat TS, Vandegraaff N, Jeevarajah D, Le G, Jones ED, Smith JA, Coates JAV, Winfield LJ, Thienthong N, Newman J, Lucent D, Ryan JH, Savage GP, Francis CL, Deadman JJ. Structural basis for a new mechanism of inhibition of HIV-1 integrase identified by fragment screening and structure-based design. Antivir Chem Chemother 2011; 21:155-68. [PMID: 21602613 DOI: 10.3851/imp1716] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND HIV-1 integrase is a clinically validated therapeutic target for the treatment of HIV-1 infection, with one approved therapeutic currently on the market. This enzyme represents an attractive target for the development of new inhibitors to HIV-1 that are effective against the current resistance mutations. METHODS A fragment-based screening method employing surface plasmon resonance and NMR was initially used to detect interactions between integrase and fragments. The binding sites of the fragments were elucidated by crystallography and the structural information used to design and synthesize improved ligands. RESULTS The location of binding of fragments to the catalytic core of integrase was found to be in a previously undescribed binding site, adjacent to the mobile loop. Enzyme assays confirmed that formation of enzyme-fragment complexes inhibits the catalytic activity of integrase and the structural data was utilized to further develop these fragments into more potent novel enzyme inhibitors. CONCLUSIONS We have defined a new site in integrase as a valid region for the structure-based design of allosteric integrase inhibitors. Using a structure-based design process we have improved the activity of the initial fragments 45-fold.
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20
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Fitzkee NC, Torchia DA, Bax A. Measuring rapid hydrogen exchange in the homodimeric 36 kDa HIV-1 integrase catalytic core domain. Protein Sci 2011; 20:500-12. [PMID: 21213249 DOI: 10.1002/pro.582] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 10/07/2010] [Indexed: 11/12/2022]
Abstract
Measurements of rapid hydrogen exchange (HX) of water with protein amide sites contain valuable information on protein structure and function, but current NMR methods for measuring HX rates are limited in their applicability to large protein systems. An alternate method for measuring rapid HX is presented that is well-suited for larger proteins, and we apply the method to the deuterated, homodimeric 36 kDa HIV-1 integrase catalytic core domain (CCD). Using long mixing times for water-amide magnetization exchange at multiple pH values, HX rates spanning more than four orders of magnitude were measured, as well as NOE cross-relaxation rates to nearby exchangeable protons. HX protection factors for the CCD are found to be large (>10(4)) for residues along the dimer interface, but much smaller in many other regions. Notably, the catalytic helix (residues 152-167) exhibits low HX protection at both ends, indicative of fraying at both termini as opposed to just the N-terminal end, as originally thought. Residues in the LEDGF/p75 binding pocket also show marginal stability, with protection factors in the 10-100 range (∼1.4-2.7 kcal/mol). Additionally, elevated NOE cross-relaxation rates are identified and, as expected, correspond to proximity of the amide proton to a rapidly exchanging proton, typically from an OH side chain. Indirect NOE transfer between H(2) O and the amide proton of I141, a residue in the partially disordered active site of the enzyme, suggests its proximity to the side chain of S147, an interaction seen in the DNA-bound form for a homologous integrase.
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Affiliation(s)
- Nicholas C Fitzkee
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA
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21
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Wielens J, Headey SJ, Deadman JJ, Rhodes DI, Le GT, Parker MW, Chalmers DK, Scanlon MJ. Fragment-based design of ligands targeting a novel site on the integrase enzyme of human immunodeficiency virus 1. ChemMedChem 2010; 6:258-61. [PMID: 21275048 DOI: 10.1002/cmdc.201000483] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Indexed: 01/24/2023]
Affiliation(s)
- Jerome Wielens
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Australia
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22
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Fitzkee NC, Bax A. Facile measurement of ¹H-¹5N residual dipolar couplings in larger perdeuterated proteins. JOURNAL OF BIOMOLECULAR NMR 2010; 48:65-70. [PMID: 20694505 PMCID: PMC2950907 DOI: 10.1007/s10858-010-9441-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 07/22/2010] [Indexed: 05/11/2023]
Abstract
We present a simple method, ARTSY, for extracting ¹J(NH) couplings and ¹H-¹⁵N RDCs from an interleaved set of two-dimensional ¹H-¹⁵N TROSY-HSQC spectra, based on the principle of quantitative J correlation. The primary advantage of the ARTSY method over other methods is the ability to measure couplings without scaling peak positions or altering the narrow line widths characteristic of TROSY spectra. Accuracy of the method is demonstrated for the model system GB3. Application to the catalytic core domain of HIV integrase, a 36 kDa homodimer with unfavorable spectral characteristics, demonstrates its practical utility. Precision of the RDC measurement is limited by the signal-to-noise ratio, S/N, achievable in the 2D TROSY-HSQC spectrum, and is approximately given by 30/(S/N) Hz.
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Affiliation(s)
- Nicholas C Fitzkee
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
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