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Aoki M, Aoki-Ogata H, Bulut H, Hayashi H, Takamune N, Kishimoto N, Tanaka H, Higashi-Kuwata N, Hattori SI, Das D, Venkateswara Rao K, Iwama K, Davis DA, Hasegawa K, Murayama K, Yarchoan R, Ghosh AK, Pau AK, Machida S, Misumi S, Mitsuya H. GRL-142 binds to and impairs HIV-1 integrase nuclear localization signal and potently suppresses highly INSTI-resistant HIV-1 variants. SCIENCE ADVANCES 2023; 9:eadg2955. [PMID: 37436982 PMCID: PMC10337902 DOI: 10.1126/sciadv.adg2955] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 06/08/2023] [Indexed: 07/14/2023]
Abstract
Nuclear localization signal (NLS) of HIV-1 integrase (IN) is implicated in nuclear import of HIV-1 preintegration complex (PIC). Here, we established a multiclass drug-resistant HIV-1 variant (HIVKGD) by consecutively exposing an HIV-1 variant to various antiretroviral agents including IN strand transfer inhibitors (INSTIs). HIVKGD was extremely susceptible to a previously reported HIV-1 protease inhibitor, GRL-142, with IC50 of 130 femtomolar. When cells were exposed to HIVKGD IN-containing recombinant HIV in the presence of GRL-142, significant decrease of unintegrated 2-LTR circular cDNA was observed, suggesting that nuclear import of PIC was severely compromised by GRL-142. X-ray crystallographic analyses revealed that GRL-142 interacts with NLS's putative sequence (DQAEHLK) and sterically blocks the nuclear transport of GRL-142-bound HIVKGD's PIC. Highly INSTI-resistant HIV-1 variants isolated from heavily INSTI-experienced patients proved to be susceptible to GRL-142, suggesting that NLS-targeting agents would serve as salvage therapy agents for highly INSTI-resistant variant-harboring individuals. The data should offer a new modality to block HIV-1 infectivity and replication and shed light on developing NLS inhibitors for AIDS therapy.
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Affiliation(s)
- Manabu Aoki
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Medical Technology, Kumamoto Health Science University, Kumamoto, Japan
- Department of Refractory Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
| | - Hiromi Aoki-Ogata
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Refractory Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
| | - Haydar Bulut
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Hironori Hayashi
- Department of Intelligent Network for Infection Control, Tohoku University Graduate School of Medicine, Miyagi, Japan
- Department of infectious Diseases, International Research Institute of Disaster Science, Tohoku University, Miyagi, Japan
| | - Nobutoki Takamune
- Department of Environmental and Molecular Health Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Naoki Kishimoto
- Department of Environmental and Molecular Health Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Hiroki Tanaka
- Department of Structural Virology, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
| | - Nobuyo Higashi-Kuwata
- Department of Refractory Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
| | - Shin-ichiro Hattori
- Department of Refractory Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
| | - Debananda Das
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | | | - Kazuya Iwama
- Department of Intelligent Network for Infection Control, Tohoku University Graduate School of Medicine, Miyagi, Japan
- Department of infectious Diseases, International Research Institute of Disaster Science, Tohoku University, Miyagi, Japan
| | - David A. Davis
- Viral Oncology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kazuya Hasegawa
- Structural Biology Division, Japan Synchrotron Radiation Research Institute, Hyogo, Japan
| | - Kazutaka Murayama
- Division of Biomedical Measurements and Diagnostics, Graduate School of Biomedical Engineering, Tohoku University, Miyagi, Japan
| | - Robert Yarchoan
- Viral Oncology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Arun K. Ghosh
- Departments of Chemistry and Medicinal Chemistry, Purdue University, West Lafayette, IN, USA
| | - Alice K. Pau
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Shinichi Machida
- Department of Structural Virology, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
| | - Shogo Misumi
- Department of Environmental and Molecular Health Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Hiroaki Mitsuya
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Refractory Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
- Division of Clinical Sciences, Kumamoto University Hospital, Kumamoto, Japan
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Song Y, Zhang H, Wang Y, Guo J, Tang S, Wang L, Peng K, Dong CS. Importin KPNA2 confers HIV-1 pre-integration complex nuclear import by interacting with the capsid protein. Antiviral Res 2022; 200:105289. [PMID: 35301060 DOI: 10.1016/j.antiviral.2022.105289] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/03/2022] [Accepted: 03/10/2022] [Indexed: 11/19/2022]
Abstract
For human immunodeficiency virus 1 (HIV-1) to infect non-dividing cells, pre-integration complex (PIC) must be transported into the nucleus within the replication cycle. We previously reported that the karyopherin β1 (KPNB1)-nucleoporin Pom121 pathway, related to the downstream process of PIC nuclear import, mediates efficient HIV-1 PIC nuclear import. Further, our earlier RNA transcriptome sequencing revealed that karyopherin α2 (KPNA2) was among the differentially expressed importin family members during monocyte to macrophage differentiation. Although PIC transport into the nucleus in HIV-1 has been widely studied, much remains to be understood about it. In this study, we confirmed our previous RNA sequencing results and found that HIV-1 replication was significantly lower in 293T cells with siRNA-mediated KPNA2 knockdown and higher in KPNA2-upregulated cells. Quantitative PCR indicated that viral replication was impaired during cDNA nuclear import. The N-terminal of the capsid protein p24 interacted with KPNA2, and KPNB1 participated in KPNA2-mediated PIC nuclear import. Disruption of the capsid-KPNA2 binding by overexpression of full-length p24 or p24 N-terminal impaired the PIC nuclear import. These results indicate that KPNA2 is an important upstream adaptor of the KPNB1-Pom121 axis, thereby mediating HIV-1 PIC nuclear transportation. KPNA2 is thus a potential target for HIV-1 antiviral treatment.
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Affiliation(s)
- Yanhui Song
- Center of Clinical Laboratory, The First Affiliated Hospital of Soochow University, Soochow University, China.
| | - Hongguang Zhang
- The Institutes of Biology and Medical Sciences, Soochow University, China
| | - Yinmiao Wang
- Center of Clinical Laboratory, The First Affiliated Hospital of Soochow University, Soochow University, China
| | - Jin Guo
- The Institutes of Biology and Medical Sciences, Soochow University, China
| | - Shengjie Tang
- The Institutes of Biology and Medical Sciences, Soochow University, China
| | - Lu Wang
- The Institutes of Biology and Medical Sciences, Soochow University, China
| | - Ke Peng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, China
| | - Chun-Sheng Dong
- The Institutes of Biology and Medical Sciences, Soochow University, China.
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Jia N, Zhang X, Li W, Chen D, Hu H. Phospholipid-Coated Guanosine Diphosphate Auxiliary CaP Active Nanoparticles Can Systematically Improve the Efficiency of Gene Therapy for Cancer Disease. ACS Biomater Sci Eng 2020; 6:2107-2116. [PMID: 33455334 DOI: 10.1021/acsbiomaterials.0c00316] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Endogenous active substance guanosine diphosphate (GDP) is involved in the physiological process of DNA transfection and expression in the cytoplasm by binding to Ran proteins. To substantially improve the gene delivery efficiency of nanoparticles, phospholipid-coated Ca(P-GDP)/pDNA/NLS hybrid nanoparticles were prepared using GDP as a common biophosphorus source based on the biological process of exogenous gene expression in the cells. This nanoparticle has a relative uniform particle size distribution and in vitro stability. The addition of GDP in nanoparticles significantly enhanced the gene expression efficiency with good biocompatibility. Moreover, an in vivo study further verified that hybrid nanoparticles were more effective in increasing the p53 gene expression, thus significantly inhibiting the tumor growth in the heterotopic tumor model of nude mice. These results demonstrated that phospholipid-coated Ca(P-GDP) nanoparticles were a potential nonviral gene vector to promote gene expression. The experimental results confirmed the feasibility of designing a delivery system based on active substances and provided a new solution to improve the transfection efficiency of gene drugs.
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Affiliation(s)
- Nan Jia
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang 110016, PR China
| | - Xirui Zhang
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang 110016, PR China
| | - Wenpan Li
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang 110016, PR China
| | - Dawei Chen
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang 110016, PR China
| | - Haiyang Hu
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang 110016, PR China
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Engelman AN. Multifaceted HIV integrase functionalities and therapeutic strategies for their inhibition. J Biol Chem 2019; 294:15137-15157. [PMID: 31467082 DOI: 10.1074/jbc.rev119.006901] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Antiretroviral inhibitors that are used to manage HIV infection/AIDS predominantly target three enzymes required for virus replication: reverse transcriptase, protease, and integrase. Although integrase inhibitors were the last among this group to be approved for treating people living with HIV, they have since risen to the forefront of treatment options. Integrase strand transfer inhibitors (INSTIs) are now recommended components of frontline and drug-switch antiretroviral therapy formulations. Integrase catalyzes two successive magnesium-dependent polynucleotidyl transferase reactions, 3' processing and strand transfer, and INSTIs tightly bind the divalent metal ions and viral DNA end after 3' processing, displacing from the integrase active site the DNA 3'-hydroxyl group that is required for strand transfer activity. Although second-generation INSTIs present higher barriers to the development of viral drug resistance than first-generation compounds, the mechanisms underlying these superior barrier profiles are incompletely understood. A separate class of HIV-1 integrase inhibitors, the allosteric integrase inhibitors (ALLINIs), engage integrase distal from the enzyme active site, namely at the binding site for the cellular cofactor lens epithelium-derived growth factor (LEDGF)/p75 that helps to guide integration into host genes. ALLINIs inhibit HIV-1 replication by inducing integrase hypermultimerization, which precludes integrase binding to genomic RNA and perturbs the morphogenesis of new viral particles. Although not yet approved for human use, ALLINIs provide important probes that can be used to investigate the link between HIV-1 integrase and viral particle morphogenesis. Herein, I review the mechanisms of retroviral integration as well as the promises and challenges of using integrase inhibitors for HIV/AIDS management.
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Affiliation(s)
- Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215 Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115
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Yadav P, Sur S, Desai D, Kulkarni S, Sharma V, Tandon V. Interaction of HIV-1 integrase with polypyrimidine tract binding protein and associated splicing factor (PSF) and its impact on HIV-1 replication. Retrovirology 2019; 16:12. [PMID: 31036027 PMCID: PMC6489298 DOI: 10.1186/s12977-019-0474-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 04/11/2019] [Indexed: 12/17/2022] Open
Abstract
Background The different interactions between viral proteins and cellular host proteins are required for efficient replication of HIV-1. Various reports implicated host cellular proteins as a key factor that either interact directly with HIV-1 integrase (IN) or get involved in the integration process of virus resulting in the modulation of integration step. Polypyrimidine tract binding protein and associated splicing factor (PSF) has diverse functions inside the cell such as transcriptional regulation, DNA repair, acts as nucleic acids binding protein and regulate replication and infectivity of different viruses. Results The protein binding study identified the association of host protein PSF with HIV-1 integrase. The siRNA knockdown (KD) of PSF resulted in increased viral replication in TZM-bl cells, suggesting PSF has negative influence on viral replication. The quantitative PCR of virus infected PSF knockdown TZM-bl cells showed more integrated DNA and viral cDNA as compared to control cells. We did not observe any significant difference between the amount of early reverse transcription products as well as infectivity of virus in the PSF KD and control TZM-bl cells. Molecular docking study supported the argument that PSF hinders the binding of viral DNA with IN. Conclusion In an attempt to study the host interacting protein of IN, we have identified a new interacting host protein PSF which is a splicing factor and elucidated its role in integration and viral replication. Experimental as well as in silico analysis inferred that the host protein causes not only change in the integration events but also targets the incoming viral DNA or the integrase-viral DNA complex. The role of PSF was also investigated at early reverse transcript production as well as late stages. The PSF is causing changes in integration events, but it does not over all make any changes in the virus infectivity. MD trajectory analyses provided a strong clue of destabilization of Integrase-viral DNA complex occurred due to PSF interaction with the conserved bases of viral DNA ends that are extremely crucial contact points with integrase and indispensable for integration. Thus our study emphasizes the negative influence of PSF on HIV-1 replication. Electronic supplementary material The online version of this article (10.1186/s12977-019-0474-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pooja Yadav
- Department of Chemistry, University of Delhi, Delhi, 110007, India
| | - Souvik Sur
- Special Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Dipen Desai
- National AIDS Research Institute, Pune, Maharashtra, 411026, India
| | - Smita Kulkarni
- National AIDS Research Institute, Pune, Maharashtra, 411026, India
| | - Vartika Sharma
- International Centre for Genetics Engineering and Biotechnology, New Delhi, 110067, India
| | - Vibha Tandon
- Special Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India.
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A Cas9 Ribonucleoprotein Platform for Functional Genetic Studies of HIV-Host Interactions in Primary Human T Cells. Cell Rep 2017; 17:1438-1452. [PMID: 27783955 DOI: 10.1016/j.celrep.2016.09.080] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 07/28/2016] [Accepted: 09/22/2016] [Indexed: 12/26/2022] Open
Abstract
New genetic tools are needed to understand the functional interactions between HIV and human host factors in primary cells. We recently developed a method to edit the genome of primary CD4+ T cells by electroporation of CRISPR/Cas9 ribonucleoproteins (RNPs). Here, we adapted this methodology to a high-throughput platform for the efficient, arrayed editing of candidate host factors. CXCR4 or CCR5 knockout cells generated with this method are resistant to HIV infection in a tropism-dependent manner, whereas knockout of LEDGF or TNPO3 results in a tropism-independent reduction in infection. CRISPR/Cas9 RNPs can furthermore edit multiple genes simultaneously, enabling studies of interactions among multiple host and viral factors. Finally, in an arrayed screen of 45 genes associated with HIV integrase, we identified several candidate dependency/restriction factors, demonstrating the power of this approach as a discovery platform. This technology should accelerate target validation for pharmaceutical and cell-based therapies to cure HIV infection.
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7
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Suttiprapa S, Rinaldi G, Tsai IJ, Mann VH, Dubrovsky L, Yan HB, Holroyd N, Huckvale T, Durrant C, Protasio AV, Pushkarsky T, Iordanskiy S, Berriman M, Bukrinsky MI, Brindley PJ. HIV-1 Integrates Widely throughout the Genome of the Human Blood Fluke Schistosoma mansoni. PLoS Pathog 2016; 12:e1005931. [PMID: 27764257 PMCID: PMC5072744 DOI: 10.1371/journal.ppat.1005931] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/13/2016] [Indexed: 11/18/2022] Open
Abstract
Schistosomiasis is the most important helminthic disease of humanity in terms of morbidity and mortality. Facile manipulation of schistosomes using lentiviruses would enable advances in functional genomics in these and related neglected tropical diseases pathogens including tapeworms, and including their non-dividing cells. Such approaches have hitherto been unavailable. Blood stream forms of the human blood fluke, Schistosoma mansoni, the causative agent of the hepatointestinal schistosomiasis, were infected with the human HIV-1 isolate NL4-3 pseudotyped with vesicular stomatitis virus glycoprotein. The appearance of strong stop and positive strand cDNAs indicated that virions fused to schistosome cells, the nucleocapsid internalized and the RNA genome reverse transcribed. Anchored PCR analysis, sequencing HIV-1-specific anchored Illumina libraries and Whole Genome Sequencing (WGS) of schistosomes confirmed chromosomal integration; >8,000 integrations were mapped, distributed throughout the eight pairs of chromosomes including the sex chromosomes. The rate of integrations in the genome exceeded five per 1,000 kb and HIV-1 integrated into protein-encoding loci and elsewhere with integration bias dissimilar to that of human T cells. We estimated ~ 2,100 integrations per schistosomulum based on WGS, i.e. about two or three events per cell, comparable to integration rates in human cells. Accomplishment in schistosomes of post-entry processes essential for HIV-1replication, including integrase-catalyzed integration, was remarkable given the phylogenetic distance between schistosomes and primates, the natural hosts of the genus Lentivirus. These enigmatic findings revealed that HIV-1 was active within cells of S. mansoni, and provided the first demonstration that HIV-1 can integrate into the genome of an invertebrate.
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Affiliation(s)
- Sutas Suttiprapa
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
- Department of Microbiology, Faculty of Science, Mahidol University, Phyathai, Rachthewee, Bangkok
- Department of Pathology, Faculty of Medicine, Khon Kaen University, Muang Khon Kaen, Thailand
| | - Gabriel Rinaldi
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Isheng J. Tsai
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Victoria H. Mann
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
| | - Larisa Dubrovsky
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
| | - Hong-bin Yan
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
- Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, The People's Republic of China
| | - Nancy Holroyd
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Thomas Huckvale
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Caroline Durrant
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Anna V. Protasio
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Tatiana Pushkarsky
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
| | - Sergey Iordanskiy
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, Virginia, United States of America
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Michael I. Bukrinsky
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
| | - Paul J. Brindley
- Department of Microbiology, Immunology & Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States of America
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Bai R, Zhang XJ, Li YL, Liu JP, Zhang HB, Xiao WL, Pu JX, Sun HD, Zheng YT, Liu LX. SJP-L-5, a novel small-molecule compound, inhibits HIV-1 infection by blocking viral DNA nuclear entry. BMC Microbiol 2015; 15:274. [PMID: 26630969 PMCID: PMC4667461 DOI: 10.1186/s12866-015-0605-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 11/24/2015] [Indexed: 11/15/2022] Open
Abstract
Background Small-molecule compounds that inhibit human immunodeficiency virus type 1 (HIV-1) infection can be used not only as drug candidates, but also as reagents to dissect the life cycle of the virus. Thus, it is desirable to have an arsenal of such compounds that inhibit HIV-1 infection by various mechanisms. Until now, only a few small-molecule compounds that inhibit nuclear entry of viral DNA have been documented. Results We identified a novel, small-molecule compound, SJP-L-5, that inhibits HIV-1 infection. SJP-L-5 is a nitrogen-containing, biphenyl compound whose synthesis was based on the dibenzocyclooctadiene lignan gomisin M2, an anti-HIV bioactive compound isolated from Schisandra micrantha A. C. Smith. SJP-L-5 displayed relatively low cytotoxicity (50 % cytoxicity concentrations were greater than 200 μg/ml) and high antiviral activity against a variety of HIV strains (50 % effective concentrations (EC50)) of HIV-1 laboratory-adapted strains ranged from 0.16–0.97 μg/ml; EC50s of primary isolates ranged from 1.96–5.33 μg/ml). Analyses of the viral DNA synthesis indicated that SJP-L-5 specifically blocks the entry of the HIV-1 pre-integration complex (PIC) into the nucleus. Further results implicated that SJP-L-5 inhibits the disassembly of HIV-1 particulate capsid in the cytoplasm of the infected cells. Conclusions SJP-L-5 is a novel small-molecule compound that inhibits HIV-1 nuclear entry by blocking the disassembly of the viral core. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0605-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ru Bai
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
| | - Xing-Jie Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and the Kunming Institute of Zoology of the Chinese Academy of Sciences, Kunming, 650223, P. R. China.
| | - Yan-Li Li
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
| | - Jing-Ping Liu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650204, P. R. China.
| | - Hong-Bin Zhang
- Key Laboratory of Medicinal Chemistry for Natural Resources, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091, P. R. China.
| | - Wei-Lie Xiao
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650204, P. R. China.
| | - Jian-Xin Pu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650204, P. R. China.
| | - Han-Dong Sun
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650204, P. R. China.
| | - Yong-Tang Zheng
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and the Kunming Institute of Zoology of the Chinese Academy of Sciences, Kunming, 650223, P. R. China.
| | - Li-Xin Liu
- Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
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9
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Ali MK, Kim J, Hamid FB, Shin CG. Knockdown of the host cellular protein transportin 3 attenuates prototype foamy virus infection. Biosci Biotechnol Biochem 2015; 79:943-51. [PMID: 25660973 DOI: 10.1080/09168451.2015.1008973] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Transportin 3 (TNPO3) is a member of the importin-ß superfamily proteins. Despite numerous studies, the exact molecular mechanism of TNPO3 in retroviral infection is still controversial. Here, we provide evidence for the role and mechanism of TNPO3 in the replication of prototype foamy virus (PFV). Our findings revealed that PFV infection was reduced 2-fold by knockdown (KD) of TNPO3. However, late stage of viral replication including transcription, translation, viral assembly, and release was not influenced. The differential cellular localization of PFV integrase (IN) in KD cells pinpointed a remarkable reduction of viral replication at the nuclear import step. We also found that TNPO3 interacted with PFV IN but not with Gag, suggesting that IN-TNPO3 interaction is important for nuclear import of PFV pre-integration complex. Our report enlightens the mechanism of PFV interaction with TNPO3 and support ongoing research on PFV as a promising safe vector for gene therapy.
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Affiliation(s)
- Md Khadem Ali
- a Department of Systems Biotechnology , Chung Ang University , Ansung , Republic of Korea
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10
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Levin A, Hayouka Z, Friedler A, Loyter A. Nucleocytoplasmic shuttling of HIV-1 integrase is controlled by the viral Rev protein. Nucleus 2014. [DOI: 10.4161/nucl.11300] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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11
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Haffar O, Bukrinsky M. Nuclear translocation as a novel target for anti-HIV drugs. Expert Rev Anti Infect Ther 2014; 3:41-50. [PMID: 15757456 DOI: 10.1586/14787210.3.1.41] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
During recent years, remarkable progress has been achieved in the treatment of patients infected with HIV. This progress involves not only the improvement of previously known drugs but also the introduction of new classes of anti-HIV agents. Currently, drugs targeting virus entry, reverse transcription, integration and maturation are either in clinical use or in the late stages of clinical development. Nonetheless, the high mutation rate of the virus and toxicity of the drugs, which become problematic during prolonged treatment regimens characteristic of anti-HIV therapy, drive the necessity to produce new drugs that will allow physicians to keep the virus at bay in patients on lifelong anti-HIV therapy. Ideally, such drugs would target a new step in the HIV life cycle, thus avoiding crossresistance with older compounds. One such new target for anti-HIV therapy is nuclear translocation--a process critical for HIV replication. In this article, the authors will review recent literature on the mechanisms of HIV nuclear import and will describe compounds that inhibit this step of HIV replication.
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Affiliation(s)
- Omar Haffar
- International Therapeutics, Inc., 600 Broadway Medical Center, Suite 510, Seattle, WA 98122, USA.
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Deng S, Zhou Y, Ouyang D, Xiong J, Zhang L, Tu C, Zhang K, Song Z, Zhang F. The effect of dexamethasone on lentiviral vector infection is associated with importin α. Biomed Rep 2013; 2:137-141. [PMID: 24649085 DOI: 10.3892/br.2013.194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 10/30/2013] [Indexed: 02/02/2023] Open
Abstract
Importin α (Imα) plays an important role during the shuttling of the HIV-1 preintegration complex (PIC) from the cytoplasm to the nucleus. Imα may bind to the glucocorticoid receptor (GR), which is localized to nucleus following hormone binding. However, it remains unclear whether the binding of dexamethasone (Dex) to GR affects the Imα redistribution and, thus, alters PIC import. In our study, 293T cells were transfected with the lentiviral vector (LV) carrying the luciferase (Luci) gene following Dex or RU486 pretreatment. The Luci activity (LucA) in the Dex or RU486 group was significantly higher compared to that in the control group (P≤0.01). The effects of Dex and RU486 were inhibited by the Imα inhibitor Bimax1 (P≤0.01), although the inhibitory effect of Bimax1 was alleviated by increasing the Dex dose. Furthermore, it was observed that the LucA in the 30-min Dex treatment group was lower compared to that in the 30-min Dex pretreatment group (P≤0.01). These results suggested that Dex may improve PIC import via increasing the cytoplasmic Imα levels. Kunming mice were transfected in vivo with the LV, either 30 min or 15 h following an intraperitoneal injection of Dex. The LucA in the liver of the 30-min group mice was significantly lower compared to that of the 15-h group mice (P≤0.01), suggesting that the effect of Dex on LV infection depends mainly on the suppression of immune and inflammatory responses in vivo. Taken together, our data indicated that the effect of Dex on LV infection may be associated with Imα, constituting a novel signaling pathway mediating the effects of Dex on HIV-1 infection.
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Affiliation(s)
- Shengchang Deng
- School of Medicine, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Ying Zhou
- School of Medicine, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Dong Ouyang
- Jiangxi Police College, Nanchang, Jiangxi 330103, P.R. China
| | - Junping Xiong
- School of Medicine, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Lei Zhang
- School of Medicine, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Changchun Tu
- School of Medicine, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Keping Zhang
- School of Medicine, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Zengliang Song
- Department of Neurosurgery, The Third People's Hospital of Nanchang, Nanchang, Jiangxi 330009, P.R. China
| | - Fanglin Zhang
- School of Medicine, Nanchang University, Nanchang, Jiangxi 330006, P.R. China
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Santos S, Obukhov Y, Nekhai S, Bukrinsky M, Iordanskiy S. Virus-producing cells determine the host protein profiles of HIV-1 virion cores. Retrovirology 2012; 9:65. [PMID: 22889230 PMCID: PMC3432596 DOI: 10.1186/1742-4690-9-65] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 07/15/2012] [Indexed: 11/10/2022] Open
Abstract
Background Upon HIV entry into target cells, viral cores are released and rearranged into reverse transcription complexes (RTCs), which support reverse transcription and also protect and transport viral cDNA to the site of integration. RTCs are composed of viral and cellular proteins that originate from both target and producer cells, the latter entering the target cell within the viral core. However, the proteome of HIV-1 viral cores in the context of the type of producer cells has not yet been characterized. Results We examined the proteomic profiles of the cores purified from HIV-1 NL4-3 virions assembled in Sup-T1 cells (T lymphocytes), PMA and vitamin D3 activated THP1 (model of macrophages, mMΦ), and non-activated THP1 cells (model of monocytes, mMN) and assessed potential involvement of identified proteins in the early stages of infection using gene ontology information and data from genome-wide screens on proteins important for HIV-1 replication. We identified 202 cellular proteins incorporated in the viral cores (T cells: 125, mMΦ: 110, mMN: 90) with the overlap between these sets limited to 42 proteins. The groups of RNA binding (29), DNA binding (17), cytoskeleton (15), cytoskeleton regulation (21), chaperone (18), vesicular trafficking-associated (12) and ubiquitin-proteasome pathway-associated proteins (9) were most numerous. Cores of the virions from SupT1 cells contained twice as many RNA binding proteins as cores of THP1-derived virus, whereas cores of virions from mMΦ and mMN were enriched in components of cytoskeleton and vesicular transport machinery, most probably due to differences in virion assembly pathways between these cells. Spectra of chaperones, cytoskeletal proteins and ubiquitin-proteasome pathway components were similar between viral cores from different cell types, whereas DNA-binding and especially RNA-binding proteins were highly diverse. Western blot analysis showed that within the group of overlapping proteins, the level of incorporation of some RNA binding (RHA and HELIC2) and DNA binding proteins (MCM5 and Ku80) in the viral cores from T cells was higher than in the cores from both mMΦ and mMN and did not correlate with the abundance of these proteins in virus producing cells. Conclusions Profiles of host proteins packaged in the cores of HIV-1 virions depend on the type of virus producing cell. The pool of proteins present in the cores of all virions is likely to contain factors important for viral functions. Incorporation ratio of certain RNA- and DNA-binding proteins suggests their more efficient, non-random packaging into virions in T cells than in mMΦ and mMN.
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Affiliation(s)
- Steven Santos
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University School of Medicine and Health Sciences, 2300 I Street NW, Ross Hall, Washington, DC 20037, USA
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Cellular cofactors of lentiviral integrase: from target validation to drug discovery. Mol Biol Int 2012; 2012:863405. [PMID: 22928108 PMCID: PMC3420096 DOI: 10.1155/2012/863405] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 06/03/2012] [Accepted: 06/27/2012] [Indexed: 01/30/2023] Open
Abstract
To accomplish their life cycle, lentiviruses make use of host proteins, the so-called cellular cofactors. Interactions between host cell and viral proteins during early stages of lentiviral infection provide attractive new antiviral targets. The insertion of lentiviral cDNA in a host cell chromosome is a step of no return in the replication cycle, after which the host cell becomes a permanent carrier of the viral genome and a producer of lentiviral progeny. Integration is carried out by integrase (IN), an enzyme playing also an important role during nuclear import. Plenty of cellular cofactors of HIV-1 IN have been proposed. To date, the lens epithelium-derived growth factor (LEDGF/p75) is the best studied cofactor of HIV-1 IN. Moreover, small molecules that block the LEDGF/p75-IN interaction have recently been developed for the treatment of HIV infection. The nuclear import factor transportin-SR2 (TRN-SR2) has been proposed as another interactor of HIV IN-mediating nuclear import of the virus. Using both proteins as examples, we will describe approaches to be taken to identify and validate novel cofactors as new antiviral targets. Finally, we will highlight recent advances in the design and the development of small-molecule inhibitors binding to the LEDGF/p75-binding pocket in IN (LEDGINs).
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15
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De Houwer S, Demeulemeester J, Thys W, Taltynov O, Zmajkovicova K, Christ F, Debyser Z. Identification of residues in the C-terminal domain of HIV-1 integrase that mediate binding to the transportin-SR2 protein. J Biol Chem 2012; 287:34059-68. [PMID: 22872638 DOI: 10.1074/jbc.m112.387944] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Transportin-SR2 (TRN-SR2 and TNPO3) is a cellular cofactor of HIV replication that has been implicated in the nuclear import of HIV. TRN-SR2 was originally identified in a yeast two-hybrid screen as an interaction partner of HIV integrase (IN) and in two independent siRNA screens as a cofactor of viral replication. We have now studied the interaction of TRN-SR2 and HIV IN in molecular detail and identified the TRN-SR2 interacting regions of IN. A weak interaction with the catalytic core domain (CCD) and a strong interaction with the C-terminal domain (CTD) of IN were detected. By dissecting the catalytic core domain (CCD) of IN into short structural fragments, we identified a peptide (INIP(1), amino acids (170)EHLKTAVQMAVFIHNFKRKGGI(191)) retaining the ability to interact with TRN-SR2. By dissecting the C-terminal domain (CTD) of IN, we could identify two interacting peptides (amino acids (214)QKQITKIQNFRVYYR(228) and (262)RRKVKIIRDYGK(273)) that come together in the CTD tertiary structure to form an exposed antiparallel β-sheet. Through site-specific mutagenesis, we defined the following sets of amino acids in IN as important for the interaction with TRN-SR2: Phe-185/Lys-186/Arg-187/Lys-188 in the CCD and Arg-262/Arg-263/Lys-264 and Lys-266/Arg-269 in the CTD. An HIV-1 strain carrying K266A/R269A in IN was replication-defective due to a block in reverse transcription, confounding the study of nuclear import. Insight into the IN/TRN-SR2 interaction interface is necessary to guide drug discovery efforts targeting the nuclear entry step of replication.
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Affiliation(s)
- Stephanie De Houwer
- Laboratory for Molecular Virology and Gene Therapy, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
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Levin A, Hayouka Z, Friedler A, Loyter A. Transportin 3 and importin α are required for effective nuclear import of HIV-1 integrase in virus-infected cells. Nucleus 2012; 1:422-31. [PMID: 21326825 DOI: 10.4161/nucl.1.5.12903] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 07/02/2010] [Accepted: 07/07/2010] [Indexed: 01/25/2023] Open
Abstract
Unlike other retroviruses, human immunodeficiency virus type-1 (HIV-1) can infect terminally differentiated cells, due to the ability of its pre-integration complex (PIC) to translocate via the host nuclear pore complex (NPC). The PIC Nuclear import has been suggested to be mediated by the viral integrase protein (IN), via either the importin α or transportin 3 (TNPO3/transportin-SR2) pathways.We show that in virus-infected cells, IN interacts with both importin α and TNPO3, simultaneously or separately, suggesting a multiple use of nuclear import pathways. Disruption of either the IN-importin α or IN-TNPO3 complexes in virus-infected cells by specific cell-permeable-peptides resulted in inhibition of IN and viral cDNA nuclear import. Here we show that peptides which disrupt either one of these complexes block virus infection, indicating involvement of both pathways in efficient viral replication. Formation of IN-importin α and IN-TNPO3 complexes has also been observed in IN-transfected cultured cells. Using specific peptides, we demonstrate that in transfected cells but not in virus infected cells the importin α pathway overrides that of TNPO3. The IN-importin α and IN-TNPO3 complexes were not observed in virus-infected Rev-expressing cells, indicating the Rev protein's ability to disrupt both complexes.Our work suggests that IN nuclear import requires the involvement of both importin α and TNPO3. The ability to inhibit nuclear import of the IN-DNA complex and consequently, virus infection by peptides that interrupt IN's interaction with either importin α or TNPO3 indicates that for efficient infection, nuclear import of IN should be mediated by both nuclear-import receptors.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
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HIVToolbox, an integrated web application for investigating HIV. PLoS One 2011; 6:e20122. [PMID: 21647445 PMCID: PMC3102074 DOI: 10.1371/journal.pone.0020122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 04/12/2011] [Indexed: 11/19/2022] Open
Abstract
Many bioinformatic databases and applications focus on a limited domain of knowledge federating links to information in other databases. This segregated data structure likely limits our ability to investigate and understand complex biological systems. To facilitate research, therefore, we have built HIVToolbox, which integrates much of the knowledge about HIV proteins and allows virologists and structural biologists to access sequence, structure, and functional relationships in an intuitive web application. HIV-1 integrase protein was used as a case study to show the utility of this application. We show how data integration facilitates identification of new questions and hypotheses much more rapid and convenient than current approaches using isolated repositories. Several new hypotheses for integrase were created as an example, and we experimentally confirmed a predicted CK2 phosphorylation site. Weblink: [http://hivtoolbox.bio-toolkit.com].
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Yadav SC, Kumari A, Yadav R. Development of peptide and protein nanotherapeutics by nanoencapsulation and nanobioconjugation. Peptides 2011; 32:173-87. [PMID: 20934475 DOI: 10.1016/j.peptides.2010.10.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 10/02/2010] [Accepted: 10/03/2010] [Indexed: 11/17/2022]
Abstract
The targeted delivery of therapeutic peptide by nanocarriers systems requires the knowledge of interactions of nanomaterials with the biological environment, peptide release, and stability of therapeutic peptides. Therapeutic application of nanoencapsulated peptides are increasing exponentially and >1000 peptides in nanoencapsulated form are in different clinical/trial phase. This review covers current scenario of therapeutic protein and peptides encapsulation on polymer to metallic nanocarriers including methods of protein encapsulation, peptide bioconjugation on nanoparticles, stability enhancement of encapsulated proteins and its biomedical applications.
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Affiliation(s)
- Subhash Chandra Yadav
- Nanobiology Lab, Biotechnology Division, Institute of Himalayan Bioresource Technology, Council of Scientific and Industrial Research, Palampur 176061 HP India.
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Zhang R, Mehla R, Chauhan A. Perturbation of host nuclear membrane component RanBP2 impairs the nuclear import of human immunodeficiency virus -1 preintegration complex (DNA). PLoS One 2010; 5:e15620. [PMID: 21179483 PMCID: PMC3001881 DOI: 10.1371/journal.pone.0015620] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Accepted: 11/15/2010] [Indexed: 12/12/2022] Open
Abstract
HIV-1 is a RNA virus that requires an intermediate DNA phase via reverse transcription (RT) step in order to establish productive infection in the host cell. The nascent viral DNA synthesized via RT step and the preformed viral proteins are assembled into pre-integration complex (PIC) in the cell cytoplasm. To integrate the viral DNA into the host genome, the PIC must cross cell nuclear membrane through the nuclear pore complex (NPC). RanBP2, also known as Nup358, is a major component of the cytoplasmic filaments that emanates from the nuclear pore complex and has been implicated in various nucleo-cytoplasmic transport pathways including those for HIV Rev-protein. We sought to investigate the role of RanBP2 in HIV-1 replication. In our investigations, we found that RanBP2 depletion via RNAi resulted in profound inhibition of HIV-1 infection and played a pivotal role in the nuclear entry of HIV DNA. More precisely, there was a profound decline in 2-LTR DNA copies (marker for nuclear entry of HIV DNA) and an unchanged level of viral reverse transcription in RanBP2-ablated HIV-infected cells compared to RanBP3-depleted or non-specific siRNA controls. We further demonstrated that the function of Rev was unaffected in RanBP2-depleted latently HIV infected cells (reactivated). We also serendipitously found that RanBP2 depletion inhibited the global ectopic gene expression. In conclusion, RanBP2 is a host factor that is involved in the nuclear import of HIV-1 PIC (DNA), but is not critical to the nuclear export of the viral mRNAs or nucleo-cytoplasmic shuttling of Rev. RanBP2 could be a potential target for efficient inhibition of HIV.
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Affiliation(s)
- Ruonan Zhang
- Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, United States of America
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20
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Chook YM, Süel KE. Nuclear import by karyopherin-βs: recognition and inhibition. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1593-606. [PMID: 21029754 DOI: 10.1016/j.bbamcr.2010.10.014] [Citation(s) in RCA: 300] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 10/06/2010] [Accepted: 10/19/2010] [Indexed: 01/24/2023]
Abstract
Proteins in the karyopherin-β family mediate the majority of macromolecular transport between the nucleus and the cytoplasm. Eleven of the 19 known human karyopherin-βs and 10 of the 14S. cerevisiae karyopherin-βs mediate nuclear import through recognition of nuclear localization signals or NLSs in their cargos. This receptor-mediated process is essential to cellular viability as proteins are translated in the cytoplasm but many have functional roles in the nucleus. Many known karyopherin-β-cargo interactions were discovered through studies of the individual cargos rather than the karyopherins, and this information is thus widely scattered in the literature. We consolidate information about cargos that are directly recognized by import-karyopherin-βs and review common characteristics or lack thereof among cargos of different import pathways. Knowledge of karyopherin-β-cargo interactions is also critical for the development of nuclear import inhibitors and the understanding of their mechanisms of inhibition. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.
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Affiliation(s)
- Yuh Min Chook
- Department of Pharmacology, University of Texas Southerwestern Medical Center, Dallas, TX 75206, USA.
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Iordanskiy S, Waltke M, Feng Y, Wood C. Subtype-associated differences in HIV-1 reverse transcription affect the viral replication. Retrovirology 2010; 7:85. [PMID: 20939905 PMCID: PMC2964588 DOI: 10.1186/1742-4690-7-85] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 10/12/2010] [Indexed: 01/08/2023] Open
Abstract
Background The impact of the products of the pol gene, specifically, reverse transcriptase (RT) on HIV-1 replication, evolution, and acquisition of drug resistance has been thoroughly characterized for subtype B. For subtype C, which accounts of almost 60% of HIV cases worldwide, much less is known. It has been reported that subtype C HIV-1 isolates have a lower replication capacity than B; however, the basis of these differences remains unclear. Results We analyzed the impact of the pol gene products from HIV-1 B and C subtypes on the maturation of HIV virions, accumulation of reverse transcription products, integration of viral DNA, frequency of point mutations in provirus and overall viral replication. Recombinant HIV-1 viruses of B and C subtypes comprising the pol fragments encoding protease, integrase and either the whole RT or a chimeric RT from different isolates of the C and B subtypes, were used for infection of cells expressing CXCR4 or CCR5 co-receptors. The viruses carrying different fragments of pol from the isolates of B and C subtypes did not reveal differences in Gag and GagPol processing and viral RNA incorporation into the virions. However, the presence of the whole RT from subtype C, or the chimeric RT containing either the polymerase or the connection and RNase H domains from C isolates, caused significantly slower viral replication regardless of B or C viral backbone. Subtype C RT carrying viruses displayed lower levels of accumulation of strong-stop cDNA in permeabilized virions during endogenous reverse transcription, and decreased accumulation of both strong-stop and positive strand reverse transcription products in infected cells and in isolated reverse transcription complexes. This decreased accumulation correlated with lower levels of viral DNA integration in cells infected with viruses carrying the whole RT or RT domains from subtype C isolates. The single viral genome assay analysis did not reveal significant differences in the frequency of point mutations between the RT from B or C subtypes. Conclusions These data suggest that the whole RT as well as distinct polymerase and connection-RNase H domains from subtype C HIV-1 confer a lower level of accumulation of reverse transcripts in the virions and reverse transcription complexes as compared to subtype B, resulting in a lower overall level of virus replication.
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Affiliation(s)
- Sergey Iordanskiy
- Nebraska Center for Virology, School of Biological Sciences, University of Nebraska-Lincoln, 4240 Fair Street, East Campus, Lincoln, NE 68583-0900 USA.
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Strategies to inhibit viral protein nuclear import: HIV-1 as a target. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1646-53. [PMID: 20719241 DOI: 10.1016/j.bbamcr.2010.07.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 07/16/2010] [Accepted: 07/29/2010] [Indexed: 12/22/2022]
Abstract
Nuclear import is a critical step in the life cycle of HIV-1. During the early (preintegration) stages of infection, HIV-1 has to transport its preintegration complex into the nucleus for integration into the host cell chromatin, while at the later (postintegration) stages viral regulatory proteins Tat and Rev need to get into the nucleus to stimulate transcription and regulate splicing and nuclear export of subgenomic and genomic RNAs. Given such important role of nuclear import in HIV-1 life cycle, this step presents an attractive target for antiviral therapeutic intervention. In this review, we describe the current state of our understanding of the interactions regulating nuclear import of the HIV-1 preintegration complex and describe current approaches to inhibit it. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.
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Bugatti A, Chiodelli P, Rosenbluh J, Loyter A, Rusnati M. BSA conjugates bearing multiple copies of the basic domain of HIV-1 Tat: Prototype for the development of multitarget inhibitors of extracellular Tat. Antiviral Res 2010; 87:30-9. [PMID: 20398703 DOI: 10.1016/j.antiviral.2010.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 03/02/2010] [Accepted: 04/06/2010] [Indexed: 11/19/2022]
Abstract
The transactivating factor (Tat) of HIV-1 is involved in AIDS progression and associated pathologies. Tat possesses a basic amino acid sequence implicated in heparan sulfate proteoglycan (HSPG)-mediated internalization, nuclear localization and transactivation by Tat and in the interaction of Tat with integrins and with the vascular endothelial growth factor receptor 2 (KDR) (kinase insert domain receptor). A BSA conjugate bearing an average of four copies of a peptide representing the basic domain/nuclear localization signal of Tat (BSA-Tat-NLS) inhibits transactivation by Tat exogenously added to cells but not by Tat endogenously produced after cell transfection with a tat cDNA, indicating that BSA-Tat-NLS does not interfere with Tat at an intracellular level. Surface plasmon resonance (SPR) experiments revealed that BSA-Tat-NLS binds to the HSPG analogue heparin. Accordingly, BSA-Tat-NLS binds to HSPGs of HL3T1 cell surface and inhibits HSPG-dependent Tat internalization. BSA-Tat-NLS retains its inhibitory potential when pre-incubated with HL3T1 cells before Tat administration, possibly by masking cell-surface HSPGs thus preventing Tat binding and internalization. SPR experiments revealed that BSA-Tat-NLS binds also to integrin alpha(v)beta(3) and KDR. Accordingly, it inhibits pro-angiogenic endothelial cell adhesion to Tat and motogenesis. In conclusion, BSA-Tat-NLS binds/masks three different cell-surface receptors of Tat inhibiting different biological activities. These data point to BSA-Tat-NLS as a prototype for the development of Tat-antagonists endowed with a multitargeted mechanism of action.
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Affiliation(s)
- Antonella Bugatti
- Department of Biomedical Science and Biotechnology, University of Brescia, Italy
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Levin A, Hayouka Z, Friedler A, Loyter A. Nucleocytoplasmic shuttling of HIV-1 integrase is controlled by the viral Rev protein. Nucleus 2010; 1:190-201. [PMID: 21326951 PMCID: PMC3030695 DOI: 10.4161/nucl.1.2.11300] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 01/13/2010] [Accepted: 01/14/2010] [Indexed: 01/21/2023] Open
Abstract
In the current study we show that the Rev protein of Human Immunodeficiency Virus type 1 (HIV-1) inhibits nuclear import and mediates nuclear export of the HIV-1 integrase (IN) protein, which catalyzes integration of the viral cDNA. Interaction between IN and Rev in virus infected cells, resulting in the formation of a Rev-IN complex, has been previously described by us. Here we show that nuclear import of the IN, is inhibited by early expressed Rev. No nuclear import of IN was observed when Rev-overexpressing cells were infected by wild-type HIV-1. Similarly, no translocation of IN into nuclei was observed in the presence of Rev-derived peptides. On the other hand, massive nuclear import was observed following infection by a ΔRev virus or in the presence of peptides that promote dissociation of the Rev-IN complex. Our results show that IN is only transiently present within the nuclei of infected cells. Treatment of infected cells with leptomycin B caused nuclear retention of the Rev-IN complex. Removal of the leptomycin from these treated cells resulted in nuclear export of both Rev and IN. On the other hand, disruption of the nuclear located Rev-IN complex resulted in export of only the Rev protein indicating Rev-mediated nuclear export of IN. Our results suggest the involvement of Rev in regulating the integration process by limiting the number of integration events per cell despite the presence of numerous copies of viral cDNA.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry; The Alexander Silberman Institute of Life Sciences
| | - Zvi Hayouka
- Institute of Chemistry; The Hebrew University of Jerusalem; Jerusalem, Israel
| | - Assaf Friedler
- Institute of Chemistry; The Hebrew University of Jerusalem; Jerusalem, Israel
| | - Abraham Loyter
- Department of Biological Chemistry; The Alexander Silberman Institute of Life Sciences
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Levin A, Armon-Omer A, Rosenbluh J, Melamed-Book N, Graessmann A, Waigmann E, Loyter A. Inhibition of HIV-1 integrase nuclear import and replication by a peptide bearing integrase putative nuclear localization signal. Retrovirology 2009; 6:112. [PMID: 19961612 PMCID: PMC3224947 DOI: 10.1186/1742-4690-6-112] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 12/05/2009] [Indexed: 02/08/2023] Open
Abstract
Background The integrase (IN) of human immunodeficiency virus type 1 (HIV-1) has been implicated in different steps during viral replication, including nuclear import of the viral pre-integration complex. The exact mechanisms underlying the nuclear import of IN and especially the question of whether it bears a functional nuclear localization signal (NLS) remain controversial. Results Here, we studied the nuclear import pathway of IN by using multiple in vivo and in vitro systems. Nuclear import was not observed in an importin α temperature-sensitive yeast mutant, indicating an importin α-mediated process. Direct interaction between the full-length IN and importin α was demonstrated in vivo using bimolecular fluorescence complementation assay (BiFC). Nuclear import studies in yeast cells, with permeabilized mammalian cells, or microinjected cultured mammalian cells strongly suggest that the IN bears a NLS domain located between residues 161 and 173. A peptide bearing this sequence -NLS-IN peptide- inhibited nuclear accumulation of IN in transfected cell-cycle arrested cells. Integration of viral cDNA as well as HIV-1 replication in viral cell-cycle arrested infected cells were blocked by the NLS-IN peptide. Conclusion Our present findings support the view that nuclear import of IN occurs via the importin α pathway and is promoted by a specific NLS domain. This import could be blocked by NLS-IN peptide, resulting in inhibition of viral infection, confirming the view that nuclear import of the viral pre-integration complex is mediated by viral IN.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Abstract
HIV-1 possesses an exquisite ability to infect cells independently from their cycling status by undergoing an active phase of nuclear import through the nuclear pore. This property has been ascribed to the presence of karyophilic elements present in viral nucleoprotein complexes, such as the matrix protein (MA); Vpr; the integrase (IN); and a cis-acting structure present in the newly synthesized DNA, the DNA flap. However, their role in nuclear import remains controversial at best. In the present study, we carried out a comprehensive analysis of the role of these elements in nuclear import in a comparison between several primary cell types, including stimulated lymphocytes, macrophages, and dendritic cells. We show that despite the fact that none of these elements is absolutely required for nuclear import, disruption of the central polypurine tract-central termination sequence (cPPT-CTS) clearly affects the kinetics of viral DNA entry into the nucleus. This effect is independent of the cell cycle status of the target cells and is observed in cycling as well as in nondividing primary cells, suggesting that nuclear import of viral DNA may occur similarly under both conditions. Nonetheless, this study indicates that other components are utilized along with the cPPT-CTS for an efficient entry of viral DNA into the nucleus.
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Integrase interacts with nucleoporin NUP153 to mediate the nuclear import of human immunodeficiency virus type 1. J Virol 2009; 83:6522-33. [PMID: 19369352 DOI: 10.1128/jvi.02061-08] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The ability to traverse an intact nuclear envelope and productively infect nondividing cells is a salient feature of human immunodeficiency virus type 1 (HIV-1) and other lentiviruses, but the viral factors and mechanism of nuclear entry have not been defined. HIV-1 integrase (IN) is implicated to play a role in the nuclear import of the virus, but the cellular pathway for IN trafficking and the role of IN in mediating the nuclear import of viral particles are unknown. Using a semipermeabilized cell assay, we observed that the nuclear import of IN was not the result of passive diffusion but occurred independently of cytosolic factors, metabolic energy, and the classical receptor-mediated, Ran-dependent import pathways. To determine if IN enters the nucleus by interacting with the nucleopore complex (NPC), we found that IN bound directly with the FxFG-rich C-terminal domain of nucleoporin 153 (NUP153C). When added in excess to the import assay, NUP153C inhibited the nuclear import of IN. Known binding partners of NUP153C competed with IN for binding with NUP153 and also inhibited the nuclear import of IN. In cultured cells, overexpression of NUP153C reduced the infectivity of an HIV-derived vector by interfering with the nuclear translocation of the viral cDNA. These results support a functional role for the IN-NUP153 interaction in HIV-1 replication and suggest that HIV-1 subviral particles gain access to the nucleus by interacting directly with the NPC via the binding of particle-associated IN to NUP153C.
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Merad H, Porumb H, Zargarian L, René B, Hobaika Z, Maroun RG, Mauffret O, Fermandjian S. An unusual helix turn helix motif in the catalytic core of HIV-1 integrase binds viral DNA and LEDGF. PLoS One 2009; 4:e4081. [PMID: 19119323 PMCID: PMC2607020 DOI: 10.1371/journal.pone.0004081] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Accepted: 12/04/2008] [Indexed: 01/29/2023] Open
Abstract
Background Integrase (IN) of the type 1 human immunodeficiency virus (HIV-1) catalyzes the integration of viral DNA into host cellular DNA. We identified a bi-helix motif (residues 149–186) in the crystal structure of the catalytic core (CC) of the IN-Phe185Lys variant that consists of the α4 and α5 helices connected by a 3 to 5-residue turn. The motif is embedded in a large array of interactions that stabilize the monomer and the dimer. Principal Findings We describe the conformational and binding properties of the corresponding synthetic peptide. This displays features of the protein motif structure thanks to the mutual intramolecular interactions of the α4 and α5 helices that maintain the fold. The main properties are the binding to: 1- the processing-attachment site at the LTR (long terminal repeat) ends of virus DNA with a Kd (dissociation constant) in the sub-micromolar range; 2- the whole IN enzyme; and 3- the IN binding domain (IBD) but not the IBD-Asp366Asn variant of LEDGF (lens epidermal derived growth factor) lacking the essential Asp366 residue. In our motif, in contrast to the conventional HTH (helix-turn-helix), it is the N terminal helix (α4) which has the role of DNA recognition helix, while the C terminal helix (α5) would rather contribute to the motif stabilization by interactions with the α4 helix. Conclusion The motif, termed HTHi (i, for inverted) emerges as a central piece of the IN structure and function. It could therefore represent an attractive target in the search for inhibitors working at the DNA-IN, IN-IN and IN-LEDGF interfaces.
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Affiliation(s)
- Hayate Merad
- LBPA, CNRS (UMR 8113)–Ecole Normale Supérieure de Cachan, Cachan, France
| | - Horea Porumb
- LBPA, CNRS (UMR 8113)–Ecole Normale Supérieure de Cachan, Cachan, France
| | - Loussiné Zargarian
- LBPA, CNRS (UMR 8113)–Ecole Normale Supérieure de Cachan, Cachan, France
| | - Brigitte René
- LBPA, CNRS (UMR 8113)–Ecole Normale Supérieure de Cachan, Cachan, France
| | - Zeina Hobaika
- LBPA, CNRS (UMR 8113)–Ecole Normale Supérieure de Cachan, Cachan, France
| | - Richard G. Maroun
- Département des Sciences de la Vie et de la Terre, Faculté des Sciences, Université Saint Joseph, CST-Mar Roukos, B. P. 1514, Beyrouth, Liban
| | - Olivier Mauffret
- LBPA, CNRS (UMR 8113)–Ecole Normale Supérieure de Cachan, Cachan, France
| | - Serge Fermandjian
- LBPA, CNRS (UMR 8113)–Ecole Normale Supérieure de Cachan, Cachan, France
- * E-mail:
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Christ F, Thys W, De Rijck J, Gijsbers R, Albanese A, Arosio D, Emiliani S, Rain JC, Benarous R, Cereseto A, Debyser Z. Transportin-SR2 imports HIV into the nucleus. Curr Biol 2008; 18:1192-202. [PMID: 18722123 DOI: 10.1016/j.cub.2008.07.079] [Citation(s) in RCA: 210] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 07/03/2008] [Accepted: 07/17/2008] [Indexed: 12/21/2022]
Abstract
BACKGROUND The human immunodeficiency virus type 1 (HIV-1) and other lentiviruses have the capacity to infect nondividing cells like macrophages. This requires import of the preintegration complex (PIC) through the nuclear pore. Although many cellular and viral determinants have been proposed, the mechanism leading to nuclear import is not yet understood. RESULTS Using yeast two-hybrid and pull-down, we identified and validated transportin-SR2 (TRN-SR2) as a bona fide binding partner of HIV-1 integrase. We confirmed the biological relevance of this interaction by RNAi. Depletion of TRN-SR2 interfered with the replication of HIV-1 and HIV-2 but not MoMLV in HeLaP4 cells. Knockdown of TRN-SR2 in primary macrophages likewise interfered with HIV-1 replication. Using Q-PCR, we pinpoint this block in replication to the early steps of the viral lifecycle. A reduction in 2-LTR formation suggests a block in PIC nuclear import upon siRNA-mediated knockdown. Different lines of evidence clearly proved that the late steps of viral replication are not affected. In an in vivo nuclear-import assay using labeled HIV-1 particles, the defect in nuclear import after depletion of TRN-SR2 was directly visualized. In comparison with control cell lines, the great majority of siRNA-treated cells did not contain any PIC in the nucleus. CONCLUSION Our data clearly demonstrate that TRN-SR2 is the nuclear-import factor of HIV.
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Affiliation(s)
- Frauke Christ
- Laboratory for Molecular Virology and Gene Therapy, KU Leuven and IRC, Kapucijnenvoer 33, B-3000 Leuven, Flanders, Belgium
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30
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Gabizon R, Mor M, Rosenberg MM, Britan L, Hayouka Z, Kotler M, Shalev DE, Friedler A. Using peptides to study the interaction between the p53 tetramerization domain and HIV-1 Tat. Biopolymers 2008; 90:105-16. [PMID: 18189286 DOI: 10.1002/bip.20919] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Peptides are valuable tools for studying protein-protein interactions, especially in cases of isolated protein domains and natively unfolded proteins. Here, we used peptides to quantitatively characterize the interaction between the natively unfolded HIV-1 Tat protein and the tetramerization domain of the cellular tumor suppressor protein p53. We used peptide mapping, fluorescence anisotropy, and NMR spectroscopy to perform a detailed structural and biophysical characterization of the interaction between the two proteins and elucidate its molecular mechanism, which have so far been studied using cell-based methods. We show that the p53 tetramerization domain, p53(326-355), binds directly to residues 1-35 and 47-57 in Tat. We have characterized the interaction between p53(326-355) and Tat(47-57) in detail. The p53 residues that are mainly involved in binding to Tat(47-57) are E343 and E349, which bind to the positively charged arginine-rich motif of Tat by a partly electrostatic mechanism. All oligomerization states of p53(326-355) bind Tat(47-57) without inhibiting p53 tetramerization, since the residues in p53(326-355) that bind Tat(47-57) face away from the tetramerization interface. We conclude that p53 is able to bind Tat as a transcriptionally active tetramer.
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Affiliation(s)
- Ronen Gabizon
- Institute of Chemistry, The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
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31
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An DG, Hyun U, Shin CG. Characterization of nuclear localization signals of the prototype foamy virus integrase. J Gen Virol 2008; 89:1680-1684. [PMID: 18559938 DOI: 10.1099/vir.0.83689-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
To analyse the potential karyophilic activity of prototype foamy viruses (PFVs), we expressed the PFV integrase (IN) and its mutants as fusion proteins with enhanced green fluorescence protein. The subcellular localization of the fusion proteins was investigated by fluorescence microscopy. The PFV IN was found to be karyophilic and targeted the fusion protein to the nucleus. Mutational analyses demonstrated that the PFV IN contains a potent but non-transferable nuclear localization signal (NLS) in its C-terminal domain and contains five arginine and lysine residues between amino acids 308 and 329 that are critical for its NLS function.
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Affiliation(s)
- Dog Gn An
- Department of Biotechnology, Chung-Ang University, Ansung, Kyungki 456-756, Republic of Korea
| | - Usok Hyun
- Department of Biotechnology, Chung-Ang University, Ansung, Kyungki 456-756, Republic of Korea
| | - Cha-Gyun Shin
- Department of Biotechnology, Chung-Ang University, Ansung, Kyungki 456-756, Republic of Korea
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32
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McLane LM, Pulliam KF, Devine SE, Corbett AH. The Ty1 integrase protein can exploit the classical nuclear protein import machinery for entry into the nucleus. Nucleic Acids Res 2008; 36:4317-26. [PMID: 18586821 PMCID: PMC2490736 DOI: 10.1093/nar/gkn383] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 05/29/2008] [Accepted: 05/30/2008] [Indexed: 12/26/2022] Open
Abstract
Like its retroviral relatives, the long terminal repeat retrotransposon Ty1 in the yeast Saccharomyces cerevisiae must traverse a permanently intact nuclear membrane for successful transposition and replication. For retrotransposition to occur, at least a subset of Ty1 proteins, including the Ty1 integrase, must enter the nucleus. Nuclear localization of integrase is dependent upon a C-terminal nuclear targeting sequence. However, the nuclear import machinery that recognizes this nuclear targeting signal has not been defined. We investigated the mechanism by which Ty1 integrase gains access to nuclear DNA as a model for how other retroelements, including retroviruses like HIV, may utilize cellular nuclear transport machinery to import their essential nuclear proteins. We show that Ty1 retrotransposition is significantly impaired in yeast mutants that alter the classical nuclear protein import pathway, including the Ran-GTPase, and the dimeric import receptor, importin-alpha/beta. Although Ty1 proteins are made and processed in these mutant cells, our studies reveal that an integrase reporter is not properly targeted to the nucleus in cells carrying mutations in the classical nuclear import machinery. Furthermore, we demonstrate that integrase coimmunoprecipitates with the importin-alpha transport receptor and directly binds to importin-alpha. Taken together, these data suggest Ty1 integrase can employ the classical nuclear protein transport machinery to enter the nucleus.
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Affiliation(s)
| | | | | | - Anita H. Corbett
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd, NE, Atlanta, GA 30322, USA
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33
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Armon-Omer A, Levin A, Hayouka Z, Butz K, Hoppe-Seyler F, Loya S, Hizi A, Friedler A, Loyter A. Correlation between shiftide activity and HIV-1 integrase inhibition by a peptide selected from a combinatorial library. J Mol Biol 2007; 376:971-82. [PMID: 18201721 DOI: 10.1016/j.jmb.2007.11.095] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 11/24/2007] [Accepted: 11/27/2007] [Indexed: 10/22/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) integrase (IN) protein is an emerging target for the development of anti-HIV drugs. We recently described a new approach for inhibiting IN by "shiftides"--peptides that inhibit the protein by shifting its oligomerization equilibrium from the active dimer to the inactive tetramer. In this study, we used the yeast two-hybrid system with the HIV-1 IN as a bait and a combinatorial peptide aptamer library as a prey to select peptides of 20 amino acids that specifically bind IN. Five non-homologous peptides, designated as IN-1 to IN-5, were selected. ELISA studies confirmed that IN binds the free peptides. All the five peptides interact with IN with comparable affinity (K(d approximately )10 microM), as was revealed by fluorescence anisotropy studies. Only one peptide, IN-1, inhibited the enzymatic activity of IN in vitro and the HIV-1 replication in cultured cells. In correlation, fluorescence anisotropy binding experiments revealed that of the five peptides, only the inhibitory IN-1 inhibited the DNA binding of IN. Analytical gel filtration experiments revealed that only the IN-1 and not the four other peptides shifted the oligomerization equilibrium of IN towards the tetramer. Thus, the results show a distinct correlation between the ability of the selected peptides to inhibit IN activity and that to shift its oligomerization equilibrium.
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Affiliation(s)
- Ayelet Armon-Omer
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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34
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Rosenbluh J, Hayouka Z, Loya S, Levin A, Armon-Omer A, Britan E, Hizi A, Kotler M, Friedler A, Loyter A. Interaction between HIV-1 Rev and integrase proteins: a basis for the development of anti-HIV peptides. J Biol Chem 2007; 282:15743-53. [PMID: 17403681 DOI: 10.1074/jbc.m609864200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human immunodeficiency virus 1 (HIV-1) Rev and integrase (IN) proteins are required within the nuclei of infected cells in the late and early phases of the viral replication cycle, respectively. Here we show using various biochemical methods, that these two proteins interact with each other in vitro and in vivo. Peptide mapping and fluorescence anisotropy showed that IN binds residues 1-30 and 49-74 of Rev. Following this observation, we identified two short Rev-derived peptides that inhibit the 3'-end processing and strand-transfer enzymatic activities of IN in vitro. The peptides bound IN in vitro, penetrated into cultured cells, and significantly inhibited HIV-1 in multinuclear activation of a galactosidase indicator (MAGI) and lymphoid cultured cells. Real time PCR analysis revealed that the inhibition of HIV-1 multiplication is due to inhibition of the catalytic activity of the viral IN. The present work describes novel anti-HIV-1 lead peptides that inhibit viral replication in cultured cells by blocking DNA integration in vivo.
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Affiliation(s)
- Joseph Rosenbluh
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, and Department of Organic Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
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35
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Ao Z, Huang G, Yao H, Xu Z, Labine M, Cochrane AW, Yao X. Interaction of human immunodeficiency virus type 1 integrase with cellular nuclear import receptor importin 7 and its impact on viral replication. J Biol Chem 2007; 282:13456-67. [PMID: 17360709 DOI: 10.1074/jbc.m610546200] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Similar to all other viruses, human immunodeficiency virus type 1 (HIV-1) depends heavily on cellular factors for its successful replication. In this study we have investigated the interaction of HIV-1 integrase (IN) with several host nuclear import factors using co-immunoprecipitation assays. Our results indicate that IN interacts specifically with host importin 7 (Imp7) in vivo, but does not interact with importin 8 (Imp8) or importin alpha (Rch1). In contrast, another HIV-1 karyophilic protein MAp17, which is capable of binding Rch1, fails to interact with Imp7, suggesting that IN and Map17 may interact with different cellular pathways during HIV-1 replication. Genetic analysis revealed that the C-terminal domain of IN is the region responsible for interaction between IN with Imp7, and an IN mutant (K240A,K244A/R263A,K264A) disrupted the Imp7 binding ability of the protein, indicating that both regions ((235)WKGPAKLLWKG and (262)RRKAK) within the C-terminal domain of IN are required for efficient IN/Imp7 interaction. Using a vesicular stomatitis virus G glycoprotein pseudotyped HIV single-cycle replication system, we showed that the IN/Imp7 interaction-deficient mutant was unable to mediate viral replication and displayed impairment at both viral reverse transcription and nuclear import steps. Moreover, transient knockdown of Imp7 in both HIV-1 producing and target cells resulted in a 2.5-3.5-fold inhibition of HIV infection. Altogether, our results indicate that HIV-1 IN specifically interacts with Imp7, and this viral/cellular protein interaction contributes to efficient HIV-1 infection.
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Affiliation(s)
- Zhujun Ao
- Laboratory of Molecular Human Retrovirology, Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, R3E 0W3
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36
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Busschots K, Voet A, De Maeyer M, Rain JC, Emiliani S, Benarous R, Desender L, Debyser Z, Christ F. Identification of the LEDGF/p75 binding site in HIV-1 integrase. J Mol Biol 2006; 365:1480-92. [PMID: 17137594 DOI: 10.1016/j.jmb.2006.10.094] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 10/27/2006] [Accepted: 10/30/2006] [Indexed: 10/23/2022]
Abstract
Lens epithelium-derived growth factor (LEDGF)/p75 is an important cellular co-factor for human immunodeficiency virus (HIV) replication. We originally identified LEDGF/p75 as a binding partner of integrase (IN) in human cells. The interaction has been mapped to the integrase-binding domain (IBD) of LEDGF/p75 located in the C-terminal part. We have subsequently shown that IN carrying the Q168A mutation remains enzymatically active but is impaired for interaction with LEDGF/p75. To map the integrase/LEDGF interface in more detail, we have now identified and characterized two regions within the enzyme involved in the interaction with LEDGF/p75. The first region centers around residues W131 and W132 while the second extends from I161 up to E170. For the different IN mutants the interaction with LEDGF/p75 and the enzymatic activities were determined. IN(W131A), IN(I161A), IN(R166A), IN(Q168A) and IN(E170A) are impaired for interaction with LEDGF/p75, but retain 3' processing and strand transfer activities. Due to impaired integration, an HIV-1 strain containing the W131A mutation in IN displays reduced replication capacity, whereas virus carrying IN(Q168A) is replication defective. Comparison of the wild-type IN-LEDGF/p75 co-crystal structure with that of the modelled structure of the IN(Q168A) and IN(W131A) mutant integrases corroborated our experimental data.
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Affiliation(s)
- Katrien Busschots
- Laboratory for Molecular Virology and Gene Therapy, Molecular Medicine, Katholieke Universiteit Leuven, Flanders, Belgium
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37
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Hearps A, Jans D. HIV-1 integrase is capable of targeting DNA to the nucleus via an importin alpha/beta-dependent mechanism. Biochem J 2006; 398:475-84. [PMID: 16716146 PMCID: PMC1559465 DOI: 10.1042/bj20060466] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In addition to its well-documented role in integration of the viral genome, the HIV-1 enzyme IN (integrase) is thought to be involved in the preceding step of importing the viral cDNA into the nucleus. The ability of HIV to transport its cDNA through an intact nuclear envelope allows HIV-1 to infect non-dividing cells, which is thought to be crucial for the persistent nature of HIV/AIDS. Despite this, the mechanism utilized by HIV-1 to import its cDNA into the nucleus, and the viral proteins involved, remains ill-defined. In the present study we utilize in vitro techniques to assess the nuclear import properties of the IN protein, and show that IN interacts with members of the Imp (Importin) family of nuclear transport proteins with high affinity and exhibits rapid nuclear accumulation within an in vitro assay, indicating that IN possesses potent nucleophilic potential. IN nuclear import appears to be dependent on the Imp alpha/beta heterodimer and Ran GTP (Ran in its GTP-bound state), but does not require ATP. Importantly, we show that IN is capable of binding DNA and facilitating its import into the nucleus of semi-intact cells via a process that involves basic residues within amino acids 186-188 of IN. These results confirm IN as an efficient mediator of DNA nuclear import in vitro and imply the potential for IN to fulfil such a role in vivo. These results may not only aid in highlighting potential therapeutic targets for impeding the progression of HIV/AIDS, but may also be relevant for non-viral gene delivery.
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Affiliation(s)
- Anna C. Hearps
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | - David A. Jans
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
- To whom correspondence should be addressed (email )
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38
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Kass G, Arad G, Rosenbluh J, Gafni Y, Graessmann A, Rojas MR, Gilbertson RL, Loyter A. Permeabilized mammalian cells as an experimental system for nuclear import of geminiviral karyophilic proteins and of synthetic peptides derived from their nuclear localization signal regions. J Gen Virol 2006; 87:2709-2720. [PMID: 16894212 DOI: 10.1099/vir.0.82021-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The plant-infecting geminiviruses deliver their genome and viral proteins into the host cell nucleus. Members of the family Geminiviridae possess either a bipartite genome composed of two ∼2.6 kb DNAs or a monopartite genome of ∼3.0 kb DNA. The bipartite genome of Bean dwarf mosaic virus (BDMV) encodes several karyophilic proteins, among them the capsid protein (CP) and BV1 (nuclear shuttle protein). A CP is also encoded by the monopartite genome of Tomato yellow leaf curl virus (TYLCV). Here, an in vitro assay system was used for direct demonstration of nuclear import of BDMV BV1 and TYLCV CP, as well as synthetic peptides containing their putative nuclear localization signals (NLSs). Full-length recombinant BDMV BV1 and TYLCV CP mediated import of conjugated fluorescently labelled BSA molecules into nuclei of permeabilized mammalian cells. Fluorescently labelled and biotinylated BSA conjugates bearing the synthetic peptides containing aa 3–20 of TYLCV CP (CP-NLS) or aa 84–106 of BDMV BV1 (BV1-NLS) were also imported into the nuclei of permeabilized cells. This import was blocked by the addition of unlabelled BSA–NLS peptide conjugates or excess unlabelled free NLS peptides. The CP- and BV1-NLS peptides also mediated nuclear import of fluorescently labelled BSA molecules into the nuclei of microinjected mesophyll cells of Nicotiana benthamiana leaves, demonstrating their biological function in intact plant tissue. BV1-NLS and CP-NLS were shown to mediate specific binding to importin α, both in vitro and in vivo. These results are consistent with a common nuclear-import pathway for CP and BV1, probably via importin α.
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Affiliation(s)
- Gideon Kass
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Gabriel Arad
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Joseph Rosenbluh
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yedidya Gafni
- Department of Plant Genetics, ARO, The Volcani Center, Bet-Dagan 50250, Israel
| | - Adolf Graessmann
- Institut für Molekularbiologie und Biochemie, Free University of Berlin, 14195 Berlin, Germany
| | - Maria R Rojas
- Department of Plant Pathology, University of California, Davis, CA 95616, USA
| | - Robert L Gilbertson
- Department of Plant Pathology, University of California, Davis, CA 95616, USA
| | - Abraham Loyter
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Rosenbluh J, Kapelnikov A, Shalev DE, Rusnati M, Bugatti A, Loyter A. Positively charged peptides can interact with each other, as revealed by solid phase binding assays. Anal Biochem 2006; 352:157-68. [PMID: 16581010 DOI: 10.1016/j.ab.2006.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2005] [Revised: 12/19/2005] [Accepted: 03/01/2006] [Indexed: 11/24/2022]
Abstract
Solid phase assay systems such as enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and overlay gels are used to study processes of protein-protein interactions. The common principle of all these methods is that they monitor the binding between soluble and surface-immobilized molecules. Following the use of bovine serum albumin (BSA)-peptide conjugates or isolated synthetic peptides and the above-mentioned solid phase assay systems, the results of the current work demonstrate that positively charged peptides can interact with each other. Both the ELISA and SPR methods demonstrated that the binding process reached saturation with K(d) values ranging between 1 and 14 nM. No interaction was observed between BSA conjugates bearing positively charged peptides and conjugates bearing negatively charged peptides or with pure BSA molecules, strengthening the view that interaction occurs only between positively charged peptides. However, interactions between peptides in solution were not observed by nuclear magnetic resonance (NMR) or by native gel electrophoresis. It appears that for positively charged molecules to interact, one of the binding partners must be immobilized to a surface, a process that may lead to the exposure of otherwise masked groups or atoms. We discuss the relevance of our findings for the use of solid phase assay systems to study interactions between biomolecules.
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Affiliation(s)
- Joseph Rosenbluh
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
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40
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Lu R, Ghory HZ, Engelman A. Genetic analyses of conserved residues in the carboxyl-terminal domain of human immunodeficiency virus type 1 integrase. J Virol 2005; 79:10356-68. [PMID: 16051828 PMCID: PMC1182625 DOI: 10.1128/jvi.79.16.10356-10368.2005] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 05/02/2005] [Indexed: 12/26/2022] Open
Abstract
Results of in vitro assays identified residues in the C-terminal domain (CTD) of human immunodeficiency virus type 1 (HIV-1) integrase (IN) important for IN-IN and IN-DNA interactions, but the potential roles of these residues in virus replication were mostly unknown. Sixteen CTD residues were targeted here, generating 24 mutant viruses. Replication-defective mutants were typed as class I (blocked at integration) or class II (additional reverse transcription and/or assembly defects). Most defective viruses (15 of 17) displayed reverse transcription defects. In contrast, replication-defective HIV-1(E246K) synthesized near-normal cDNA levels but processing of Pr55(gag) was largely inhibited in virus-producing cells. Because single-round HIV-1(E246K.Luc(R-)) transduced cells at approximately 8% of the wild-type level, we concluded that the late-stage processing defect contributed significantly to the overall replication defect of HIV-1(E246K). Results of complementation assays revealed that the CTD could function in trans to the catalytic core domain (CCD) in in vitro assays, and we since determined that certain class I and class II mutants defined a novel genetic complementation group that functioned in cells independently of IN domain boundaries. Seven of eight novel Vpr-IN mutant proteins efficiently trans-complemented class I active-site mutant virus, demonstrating catalytically active CTD mutant proteins during infection. Because most of these mutants inefficiently complemented a class II CCD mutant virus, the majority of CTD mutants were likely more defective for interactions with cellular and/or viral components that affected reverse transcription and/or preintegration trafficking than the catalytic activity of the IN enzyme.
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Affiliation(s)
- Richard Lu
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
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Lu R, Limón A, Devroe E, Silver PA, Cherepanov P, Engelman A. Class II integrase mutants with changes in putative nuclear localization signals are primarily blocked at a postnuclear entry step of human immunodeficiency virus type 1 replication. J Virol 2004; 78:12735-46. [PMID: 15542626 PMCID: PMC525011 DOI: 10.1128/jvi.78.23.12735-12746.2004] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Integrase has been implicated in human immunodeficiency virus type 1 (HIV-1) nuclear import. Integrase analyses, however, can be complicated by the pleiotropic nature of mutations: whereas class I mutants are integration defective, class II mutants display additional assembly and/or reverse transcription defects. We previously determined that HIV-1(V165A), originally reported as defective for nuclear import, was a class II mutant. Here we analyzed mutants containing changes in other putative nuclear localization signals, including (186)KRK(188)/(211)KELQKQITK(219) and Cys-130. Previous work established HIV-1(K186Q), HIV-1(Q214L/Q216L), and HIV-1(C130G) as replication defective, but phenotypic classification was unclear and nuclear import in nondividing cells was not addressed. Consistent with previous reports, most of the bipartite mutants studied here were replication defective. These mutants as well as HIV-1(V165A) synthesized reduced cDNA levels, but a normal fraction of mutant cDNA localized to dividing and nondividing cell nuclei. Somewhat surprisingly, recombinant class II mutant proteins were catalytically active, and class II Vpr-integrase fusion proteins efficiently complemented class I mutant virus. Since a class I Vpr-integrase mutant efficiently complemented class II mutant viruses under conditions in which class II Vpr-integrases failed to function, we conclude that classes I and II define two distinct complementation groups and suggest that class II mutants are primarily defective at a postnuclear entry step of HIV-1 replication. HIV-1(C130G) was also defective for reverse transcription, but Vpr-integrase(C130G) did not efficiently complement class I mutant HIV-1. Since HIV-1(C130A) grew like the wild type, we conclude that Cys-130 is not essential for replication and speculate that perturbation of integrase structure contributed to the pleiotropic HIV-1(C130G) phenotype.
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Affiliation(s)
- Richard Lu
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, 44 Binney St., Boston, MA 02115, USA
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Citovsky V, Kapelnikov A, Oliel S, Zakai N, Rojas MR, Gilbertson RL, Tzfira T, Loyter A. Protein interactions involved in nuclear import of the Agrobacterium VirE2 protein in vivo and in vitro. J Biol Chem 2004; 279:29528-33. [PMID: 15123622 DOI: 10.1074/jbc.m403159200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Agrobacterium, the only known organism capable of trans-kingdom DNA transfer, genetically transforms plants by transferring a segment of its DNA, T-DNA, into the nucleus of the host cell where it integrates into the plant genome. One of the central events in this genetic transformation process is nuclear import of the T-DNA molecule, which to a large degree is mediated by the bacterial virulence protein VirE2. VirE2 is distinguished by its nuclear targeting, which occurs only in plant but not in animal cells and is facilitated by the cellular VIP1 protein. The molecular mechanism of the VIP1 function is still unclear. Here, we used in vitro assays for nuclear import and quantification of protein-protein interactions to directly demonstrate formation of ternary complexes between VirE2, VIP1, and a component of the cellular nuclear import machinery, karyopherin alpha. Our results indicate that VIP1 functions as a molecular bridge between VirE2 and karyopherin alpha, allowing VirE2 to utilize the host cell nuclear import machinery even without being directly recognized by its components.
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Affiliation(s)
- Vitaly Citovsky
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, Stony Brook, New York 11794-5215, USA.
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Maertens G, Cherepanov P, Debyser Z, Engelborghs Y, Engelman A. Identification and characterization of a functional nuclear localization signal in the HIV-1 integrase interactor LEDGF/p75. J Biol Chem 2004; 279:33421-9. [PMID: 15163664 DOI: 10.1074/jbc.m404700200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human lens epithelium-derived growth factor (LEDGF)/p75 protein forms a specific nuclear complex with human immunodeficiency virus type 1 (HIV-1) integrase and is essential for nuclear localization and chromosomal association of the viral protein. We now studied nuclear import of LEDGF/p75 in live and semipermeabilized cells. We show that nuclear import of LEDGF/p75 is GTP-, Ran-, importin-alpha/beta-, and energy-dependent and that the protein competes with the canonical SV40 large T antigen nuclear localization signal (NLS) for nuclear import receptors. We identified the NLS of LEDGF/p75 through deletion analysis and site-directed mutagenesis. The LEDGF/p75 NLS, 148GRKRKAEKQ156, belongs to the canonical SV40-like family. Fusion of this short peptide to the amino terminus of Escherichia coli beta-galactosidase rendered the fusion protein nuclear, confirming that the LEDGF/p75 NLS is transferable. Moreover, a single amino acid change in the NLS was sufficient to exclude the mutant LEDGF/p75 protein from the nucleus and abolish nuclear import of HIV-1 integrase.
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Affiliation(s)
- Goedele Maertens
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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