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Li Y, Ma L, Li P. Circ_FNDC3B Promotes Cell Proliferation and Metastasis in Esophageal Squamous Cell Carcinoma via Regulating MAPK1 by Binding to miR-136-5p. Biochem Genet 2024:10.1007/s10528-023-10585-5. [PMID: 38228844 DOI: 10.1007/s10528-023-10585-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 11/01/2023] [Indexed: 01/18/2024]
Abstract
A handful of circular RNAs (circRNAs) associated with cancer progression have been indicated in esophageal squamous cell carcinoma (ESCC). The current study aimed to investigate the functional mechanism of circular RNA Fibronectin type III domain containing 3B (circ_FNDC3B) in ESCC. Circ_FNDC3B, FNDC3B, microRNA-136-5p (miR-136-5p) and mitogen-activated protein kinase 1 (MAPK1) were examined via the quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was evaluated by Cell Counting Kit-8 (CCK-8) and colony formation assays. Transwell assay was performed to measure cell migration and invasion. Protein analysis was implemented by western blot. Cell apoptosis was assessed via flow cytometry. Target interaction was affirmed using dual-luciferase reporter assay. The function analysis of circ_FNDC3B in vivo was explored by xenograft models. The upregulation of circ_FNDC3B was detected in ESCC tissues and cells. Functionally, ESCC cell proliferation and metastasis were repressed but apoptosis was promoted by circ_FNDC3B knockdown. Besides, circ_FNDC3B silence inhibited ESCC progression through MAPK1 downregulation. Further target analysis identified miR-136-5p as a target of circ_FNDC3B and an upstream control of MAPK1. Additionally, the regulation of si-circ_FNDC3B in ESCC was also dependent on targeting miR-136-5p. Moreover, circ_FNDC3B targeted miR-136-5p to affect MAPK1 level. Tumorigenesis in vivo was also suppressed by downregulating circ_FNDC3B to regulate miR-136-5p/MAPK1 axis. Circ_FNDC3B downregulation impeded the development of ESCC via the mediation of miR-136-5p/MAPK1 axis. This report afforded a novel insight into the functional mechanism of circ_FNDC3B in ESCC.
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Affiliation(s)
- Yuwei Li
- Center of Medical Genetics, Northwest Women's and Children's Hospital, Xi'an, People's Republic of China
| | - Lieting Ma
- Department of Laboratory, First Affiliated Hospital of Xi'an Jiaotong University, 277 Yanta West Road, Xi'an, 710061, Shaanxi, People's Republic of China.
| | - Peng Li
- Department of Laboratory, First Affiliated Hospital of Xi'an Jiaotong University, 277 Yanta West Road, Xi'an, 710061, Shaanxi, People's Republic of China.
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2
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Adesina A, Skouta R. Diversity-Orientated Synthesis and Biological Properties of Compounds Based on the N-Phenylquinoneimine Scaffold. Molecules 2024; 29:249. [PMID: 38202832 PMCID: PMC10780808 DOI: 10.3390/molecules29010249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 12/30/2023] [Accepted: 01/01/2024] [Indexed: 01/12/2024] Open
Abstract
The N-phenylquinoneimine scaffold is a versatile synthetic platform that has gained significant attention in the field of drug discovery due to its structural diversity and capacity to interact with biologically relevant targets. This review explores established synthetic methodologies and highlights the significant biological activities exhibited by compounds derived from this scaffold, their implications for medicinal chemistry, and the development of novel therapeutics.
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Affiliation(s)
- Adebimpe Adesina
- Department of Chemistry, Federal University of Agriculture, Abeokuta 111101, Nigeria;
| | - Rachid Skouta
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
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3
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Inferences of actinobacterial metabolites to combat Corona virus. ADVANCES IN TRADITIONAL MEDICINE 2022. [PMCID: PMC9469815 DOI: 10.1007/s13596-022-00661-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The entire globe is reeling under the magnitude of the current corona virus pandemic. This menace has proposed severe health and economic threats for all, thereby challenging our human existence itself. Since its outbreak, it has raised the concern and imperative need of developing novel and effective agents to combat viral diseases and now its variants as well. Despite the sincere and concerted efforts of scientists and pharma giants all over the world, there seems to be no ideal recourse found till date. Natural products are rich sources of novel compounds used in the treatment of infectious and non-infectious diseases. There are reports on natural products from microbes, plants and marine organisms that are active against viral targets. Actinobacteria, the largest phylum under the bacterial kingdom, is known for its secondary metabolite production with diverse bioactive potentials. Nearly 65% of antibiotics used in medicine are contributed by Actinobacteria. Compared to antibacterial and antifungal agents, antiviral compounds from Actinobacteria are less studied. In recent years Actinobacteria from under studied/extreme ecosystems are explored for their antiviral properties. Ivermectin and teicoplanin are examples of Actinobacteria-derived antiviral drugs available for commercial use. This review highlights the importance of actinobacteria as future sources of antiviral drug discovery.
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Circ_0044556 Promotes the Progression of Colorectal Cancer via the miR-665-Dependent Expression Regulation of Diaphanous Homolog 1. Dig Dis Sci 2022; 67:4458-4470. [PMID: 34822025 DOI: 10.1007/s10620-021-07310-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 11/01/2021] [Indexed: 12/23/2022]
Abstract
BACKGROUND Cancer progression can be regulated by noncoding circular RNAs. A recent study has indicated that circ_0044556 facilitated the progression of colorectal cancer. AIM This research was performed to explore the regulatory mechanism of circ_0044556 in CRC. METHODS Circ_0044556, miR-665 and Diaphanous Homolog 1 levels were detected by the quantitative real-time polymerase chain reaction. Cell proliferation analysis was performed by cell counting kit-8 assay and Edu assay. Cell cycle progression was assessed using flow cytometry. The protein examination was conducted using western blot. Transwell assay was used to analyze cell migration and invasion. Dual-luciferase reporter assay was performed to validate the interaction between targets. In vivo research was implemented by xenograft tumor assay. RESULTS Circ_0044556 was upregulated in colorectal cancer samples and cells. Silencing circ_0044556 inhibited cell proliferation, cell cycle progression, migration, invasion, and epithelial-mesenchymal transition in CRC cells. Circ_0044556 could directly target miR-665 and the function of circ_0044556 was associated with the regulation of miR-665. In addition, Diaphanous Homolog 1 was a target gene for miR-665 and the anti-tumor role of miR-665 in colorectal cancer was dependent on the downregulation of Diaphanous Homolog 1. Diaphanous Homolog 1 level was regulated by circ_0044556 via sponging miR-665 in CRC cells. In vivo assay suggested that circ_0044556 promoted CRC tumor growth by regulating the miR-665 and Diaphanous Homolog 1 levels. CONCLUSION Our findings manifested that circ_0044556 functioned as an oncogenic circRNA in colorectal cancer by mediating the miR-665/Diaphanous Homolog 1 axis, elucidating the molecular mechanism of circ_0044556 in CRC progression.
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Lu XJ, Du N, Zhang DB, Zhou XX, Li XF, Ju JH, Hu ZL, Wang LY. Efficient, green, and rapid strategy for separating actinomycin D and X 2 using supercritical fluid chromatography. J Pharm Biomed Anal 2020; 195:113835. [PMID: 33328146 DOI: 10.1016/j.jpba.2020.113835] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 11/11/2020] [Accepted: 12/04/2020] [Indexed: 11/26/2022]
Abstract
Actinomycin D has long been used as a first-line antitumor drug in clinical practice. Actinomycin X2, a new drug lead, is often isolated along with actinomycin D. The minor differences between the two actinomycin analogs pose a daunting challenge in separation. In this study, supercritical fluid chromatography (SFC) was successfully utilized for the purification of actinomycin X2 and actinomycin D from a marine derived Streptomyces sp. DQS-5. After one-step SFC purification, the purities of these two compounds were determined to be 97.3 % and 97.8 %, respectively. This method provides a green alternative for the separation of these pharmacologically important actinomycin antibiotics. This study also demonstrated the development of a simple and rapid method for the separation of natural products based on SFC.
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Affiliation(s)
- Xiao-Jie Lu
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Na Du
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Da-Bing Zhang
- Jiangsu Hanbon Science and Technology Co., Ltd., Jiangsu, China
| | - Xiao-Xue Zhou
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Xiao-Fan Li
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Jian-Hua Ju
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou, 510301, China
| | - Zhang-Li Hu
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Li-Yan Wang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China.
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Bai L, Chen P, Xiang J, Sun J, Lei X. Enantiomeric NMR discrimination of carboxylic acids using actinomycin D as a chiral solvating agent. Org Biomol Chem 2019; 17:1466-1470. [DOI: 10.1039/c8ob03012j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We extended actinomycin D as a practical CSA for rapid enantiomeric determination of chiral carboxylic acids by1H NMR spectroscopy.
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Affiliation(s)
- Liwen Bai
- School of Pharmaceutical Sciences
- South Central University for Nationalities
- Wuhan
- P.R. China
| | - Pian Chen
- School of Pharmaceutical Sciences
- South Central University for Nationalities
- Wuhan
- P.R. China
| | - Jiangxia Xiang
- School of Pharmaceutical Sciences
- South Central University for Nationalities
- Wuhan
- P.R. China
| | - Jiarui Sun
- School of Pharmaceutical Sciences
- South Central University for Nationalities
- Wuhan
- P.R. China
| | - Xinxiang Lei
- School of Pharmaceutical Sciences
- South Central University for Nationalities
- Wuhan
- P.R. China
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7
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René B, Mauffret O, Fossé P. Retroviral nucleocapsid proteins and DNA strand transfers. BIOCHIMIE OPEN 2018; 7:10-25. [PMID: 30109196 PMCID: PMC6088434 DOI: 10.1016/j.biopen.2018.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/08/2018] [Indexed: 12/12/2022]
Abstract
An infectious retroviral particle contains 1000-1500 molecules of the nucleocapsid protein (NC) that cover the diploid RNA genome. NC is a small zinc finger protein that possesses nucleic acid chaperone activity that enables NC to rearrange DNA and RNA molecules into the most thermodynamically stable structures usually those containing the maximum number of base pairs. Thanks to the chaperone activity, NC plays an essential role in reverse transcription of the retroviral genome by facilitating the strand transfer reactions of this process. In addition, these reactions are involved in recombination events that can generate multiple drug resistance mutations in the presence of anti-HIV-1 drugs. The strand transfer reactions rely on base pairing of folded DNA/RNA structures. The molecular mechanisms responsible for NC-mediated strand transfer reactions are presented and discussed in this review. Antiretroviral strategies targeting the NC-mediated strand transfer events are also discussed.
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Affiliation(s)
- Brigitte René
- LBPA, ENS Paris-Saclay, UMR 8113, CNRS, Université Paris-Saclay, 61 Avenue du Président Wilson, 94235, Cachan, France
| | - Olivier Mauffret
- LBPA, ENS Paris-Saclay, UMR 8113, CNRS, Université Paris-Saclay, 61 Avenue du Président Wilson, 94235, Cachan, France
| | - Philippe Fossé
- LBPA, ENS Paris-Saclay, UMR 8113, CNRS, Université Paris-Saclay, 61 Avenue du Président Wilson, 94235, Cachan, France
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8
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Tietjen I, Williams DE, Read S, Kuang XT, Mwimanzi P, Wilhelm E, Markle T, Kinloch NN, Naphen CN, Tenney K, Mesplède T, Wainberg MA, Crews P, Bell B, Andersen RJ, Brumme ZL, Brockman MA. Inhibition of NF-κB-dependent HIV-1 replication by the marine natural product bengamide A. Antiviral Res 2018; 152:94-103. [PMID: 29476895 DOI: 10.1016/j.antiviral.2018.02.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 12/01/2022]
Abstract
HIV-1 inhibitors that act by mechanisms distinct from existing antiretrovirals can provide novel insights into viral replication and potentially inform development of new therapeutics. Using a multi-cycle HIV-1 replication assay, we screened 252 pure compounds derived from marine invertebrates and microorganisms and identified 6 (actinomycin Z2, bastadin 6, bengamide A, haliclonacyclamine A + B, keramamine C, neopetrosiamide B) that inhibited HIV-1 with 50% effective concentrations (EC50s) of 3.8 μM or less. The most potent inhibitor, bengamide A, blocked HIV-1 in a T cell line with an EC50 of 0.015 μM and in peripheral blood mononuclear cells with an EC50 of 0.032 μM. Bengamide A was previously described to inhibit NF-κB signaling. Consistent with this mechanism, bengamide A suppressed reporter expression from an NF-κB-driven minimal promoter and an HIV-1 long terminal repeat (LTR) with conserved NF-κB response elements, but lacked activity against an LTR construct with mutation of these elements. In single-cycle HIV-1 infection assays, bengamide A also suppressed viral protein expression when viruses encoded an intact LTR but exhibited minimal activity against those with mutated NF-κB elements. Finally, bengamide A did not inhibit viral DNA accumulation, indicating that it likely acts downstream of this step in HIV-1 replication. Our study identifies multiple new antiviral compounds including an unusually potent inhibitor of HIV-1 gene expression.
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Affiliation(s)
- Ian Tietjen
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada.
| | - David E Williams
- Departments of Chemistry and Earth, Ocean & Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Silven Read
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Xiaomei T Kuang
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Philip Mwimanzi
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Emmanuelle Wilhelm
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Tristan Markle
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Natalie N Kinloch
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Cassandra N Naphen
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, USA
| | - Karen Tenney
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, USA
| | - Thibault Mesplède
- McGill AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Mark A Wainberg
- McGill AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Phillip Crews
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, USA
| | - Brendan Bell
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Raymond J Andersen
- Departments of Chemistry and Earth, Ocean & Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Zabrina L Brumme
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada; British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada.
| | - Mark A Brockman
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada; British Columbia Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada.
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9
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Iraci N, Tabarrini O, Santi C, Sancineto L. NCp7: targeting a multitask protein for next-generation anti-HIV drug development part 2. Noncovalent inhibitors and nucleic acid binders. Drug Discov Today 2018; 23:687-695. [PMID: 29326078 DOI: 10.1016/j.drudis.2018.01.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 10/25/2017] [Accepted: 01/04/2018] [Indexed: 02/06/2023]
Abstract
Nucleocapsid protein 7 (NCp7) represents a viable target not yet reached by the currently available antiretrovirals. It is a small and highly basic protein, which is essential for multiple stages of the viral replicative cycle, with its structure preserved in all viral strains, including clinical isolates. NCp7 can be inhibited covalently, noncovalently and by shielding the nucleic acid (NA) substrates of its chaperone activity. Although covalent NCp7 inhibitors have already been detailed in the first part of this review series, the focus here is based on noncovalent and NA-binder inhibitors and on the analysis of the NCp7 3D structure to deliver fruitful insights for future drug design strategies.
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Affiliation(s)
- Nunzio Iraci
- Department of Pharmacy, University of Salerno, Fisciano, Salerno, Italy
| | - Oriana Tabarrini
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | - Claudio Santi
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | - Luca Sancineto
- Department of Heterorganic Chemistry, Centre of Molecular and Macromulecular Studies, Lodz, Poland.
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10
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Chen Y, Maskri O, Chaminade F, René B, Benkaroun J, Godet J, Mély Y, Mauffret O, Fossé P. Structural Insights into the HIV-1 Minus-strand Strong-stop DNA. J Biol Chem 2016; 291:3468-82. [PMID: 26668324 DOI: 10.1074/jbc.m115.708099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Indexed: 11/06/2022] Open
Abstract
An essential step of human immunodeficiency virus type 1 (HIV-1) reverse transcription is the first strand transfer that requires base pairing of the R region at the 3'-end of the genomic RNA with the complementary r region at the 3'-end of minus-strand strong-stop DNA (ssDNA). HIV-1 nucleocapsid protein (NC) facilitates this annealing process. Determination of the ssDNA structure is needed to understand the molecular basis of NC-mediated genomic RNA-ssDNA annealing. For this purpose, we investigated ssDNA using structural probes (nucleases and potassium permanganate). This study is the first to determine the secondary structure of the full-length HIV-1 ssDNA in the absence or presence of NC. The probing data and phylogenetic analysis support the folding of ssDNA into three stem-loop structures and the presence of four high-affinity binding sites for NC. Our results support a model for the NC-mediated annealing process in which the preferential binding of NC to four sites triggers unfolding of the three-dimensional structure of ssDNA, thus facilitating interaction of the r sequence of ssDNA with the R sequence of the genomic RNA. In addition, using gel retardation assays and ssDNA mutants, we show that the NC-mediated annealing process does not rely on a single pathway (zipper intermediate or kissing complex).
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Affiliation(s)
- Yingying Chen
- From the LBPA, ENS Cachan, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan cedex, France, the School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China, and
| | - Ouerdia Maskri
- From the LBPA, ENS Cachan, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan cedex, France
| | - Françoise Chaminade
- From the LBPA, ENS Cachan, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan cedex, France
| | - Brigitte René
- From the LBPA, ENS Cachan, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan cedex, France
| | - Jessica Benkaroun
- From the LBPA, ENS Cachan, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan cedex, France
| | - Julien Godet
- the Laboratoire de Biophotonique et Pharmacologie, UMR-CNRS 7213, Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, 67401 Illkirch-Cedex, France
| | - Yves Mély
- the Laboratoire de Biophotonique et Pharmacologie, UMR-CNRS 7213, Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, 67401 Illkirch-Cedex, France
| | - Olivier Mauffret
- From the LBPA, ENS Cachan, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan cedex, France
| | - Philippe Fossé
- From the LBPA, ENS Cachan, CNRS, Université Paris-Saclay, 61 avenue du Président Wilson, 94235 Cachan cedex, France,
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11
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Pakkianathan BC, Singh NK, König S, Krishnan M. Antiapoptotic activity of 30 kDa lipoproteins family from fat body tissue of silkworm, Bombyx mori. INSECT SCIENCE 2015; 22:629-638. [PMID: 24591444 DOI: 10.1111/1744-7917.12119] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/22/2014] [Indexed: 06/03/2023]
Abstract
The family of 30 kDa lipoproteins (LP1-5) is abundant in silkworm pupa fat body (FB) and hemolymph. One of its members, the 29 kDa protein decreased in concentration from peripheral (PP) FB tissue but was sustained in perivisceral (PV) FB tissue at the time of apoptosis. This study investigated the correlation of the 30 kDa proteins with FB apoptosis. Two protein fractions were purified, a 29 and a 30/31 kDa protein fraction, and they were used to test for activity against actinomycin D-induced apoptosis in the FB tissues. Concentrations as little as 50 μg/mL of the 29 kDa protein fraction efficiently inhibited apoptosis. Less antiapoptotic activity was detected for the higher MW fraction; DNA fragmentation was observed in FB tissue treated with 50 μg/mL of the 30/31 kDa fraction. The viability of the cells in the 29 kDa protein-supplemented culture was 40% higher than in the 31 kDa protein-supplemented culture. However, the 30 kDa lipoproteins were not able to prevent scheduled FB degeneration during silkworm metamorphosis. Thus, it is hypothesized that the antiapoptotic 29 kDa protein needs to be proteolytically degraded by a regulatory mechanism to allow programmed cell death of FB tissue.
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Affiliation(s)
| | - Nitin Kumar Singh
- Department of Environmental Biotechnology, Bharathidasan University, Tiruchirappalli, India
| | - Simone König
- Integrated Functional Genomics, Interdisciplinary Center for Clinical Research, University of Münster, Germany
| | - Muthukalingan Krishnan
- Department of Environmental Biotechnology, Bharathidasan University, Tiruchirappalli, India
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12
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Library preparation methods for next-generation sequencing: tone down the bias. Exp Cell Res 2014; 322:12-20. [PMID: 24440557 DOI: 10.1016/j.yexcr.2014.01.008] [Citation(s) in RCA: 250] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 01/07/2014] [Accepted: 01/08/2014] [Indexed: 11/22/2022]
Abstract
Next-generation sequencing (NGS) has caused a revolution in biology. NGS requires the preparation of libraries in which (fragments of) DNA or RNA molecules are fused with adapters followed by PCR amplification and sequencing. It is evident that robust library preparation methods that produce a representative, non-biased source of nucleic acid material from the genome under investigation are of crucial importance. Nevertheless, it has become clear that NGS libraries for all types of applications contain biases that compromise the quality of NGS datasets and can lead to their erroneous interpretation. A detailed knowledge of the nature of these biases will be essential for a careful interpretation of NGS data on the one hand and will help to find ways to improve library quality or to develop bioinformatics tools to compensate for the bias on the other hand. In this review we discuss the literature on bias in the most common NGS library preparation protocols, both for DNA sequencing (DNA-seq) as well as for RNA sequencing (RNA-seq). Strikingly, almost all steps of the various protocols have been reported to introduce bias, especially in the case of RNA-seq, which is technically more challenging than DNA-seq. For each type of bias we discuss methods for improvement with a view to providing some useful advice to the researcher who wishes to convert any kind of raw nucleic acid into an NGS library.
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13
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Levin JG. Obituary. Virus Res 2013; 171:356. [PMID: 23414628 DOI: 10.1016/j.virusres.2012.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Judith G Levin
- Section on Viral Gene Regulation, Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2780, USA.
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14
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Sajid I, Shaaban KA, Hasnain S. Antitumour compounds from a saline soil isolate,Streptomyces griseoincarnatusCTF15. Nat Prod Res 2011; 25:549-59. [DOI: 10.1080/14786419.2010.534993] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Levin JG, Mitra M, Mascarenhas A, Musier-Forsyth K. Role of HIV-1 nucleocapsid protein in HIV-1 reverse transcription. RNA Biol 2010; 7:754-74. [PMID: 21160280 DOI: 10.4161/rna.7.6.14115] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The HIV-1 nucleocapsid protein (NC) is a nucleic acid chaperone, which remodels nucleic acid structures so that the most thermodynamically stable conformations are formed. This activity is essential for virus replication and has a critical role in mediating highly specific and efficient reverse transcription. NC's function in this process depends upon three properties: (1) ability to aggregate nucleic acids; (2) moderate duplex destabilization activity; and (3) rapid on-off binding kinetics. Here, we present a detailed molecular analysis of the individual events that occur during viral DNA synthesis and show how NC's properties are important for almost every step in the pathway. Finally, we also review biological aspects of reverse transcription during infection and the interplay between NC, reverse transcriptase, and human APOBEC3G, an HIV-1 restriction factor that inhibits reverse transcription and virus replication in the absence of the HIV-1 Vif protein.
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Affiliation(s)
- Judith G Levin
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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16
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Comprehensive comparative analysis of strand-specific RNA sequencing methods. Nat Methods 2010; 7:709-15. [PMID: 20711195 PMCID: PMC3005310 DOI: 10.1038/nmeth.1491] [Citation(s) in RCA: 529] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Accepted: 07/20/2010] [Indexed: 12/17/2022]
Abstract
Strand-specific, massively parallel cDNA sequencing (RNA-seq) is a powerful tool for transcript discovery, genome annotation and expression profiling. There are multiple published methods for strand-specific RNA-seq, but no consensus exists as to how to choose between them. Here we developed a comprehensive computational pipeline to compare library quality metrics from any RNA-seq method. Using the well-annotated Saccharomyces cerevisiae transcriptome as a benchmark, we compared seven library-construction protocols, including both published and our own methods. We found marked differences in strand specificity, library complexity, evenness and continuity of coverage, agreement with known annotations and accuracy for expression profiling. Weighing each method's performance and ease, we identified the dUTP second-strand marking and the Illumina RNA ligation methods as the leading protocols, with the former benefitting from the current availability of paired-end sequencing. Our analysis provides a comprehensive benchmark, and our computational pipeline is applicable for assessment of future protocols in other organisms.
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17
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Goldschmidt V, Miller Jenkins LM, de Rocquigny H, Darlix JL, Mély Y. The nucleocapsid protein of HIV-1 as a promising therapeutic target for antiviral drugs. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/hiv.10.3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The nucleocapsid protein (NCp7) is a major HIV-1 structural protein that plays key roles in viral replication, mainly through its conserved zinc fingers that direct specific interactions with the viral nucleic acids. Owing to its high degree of conservation and critical functions, NCp7 represents a target of choice for drugs that can potentially complement HAART, thus possibly impairing the circulation of drug-resistant HIV-1 strains. Zinc ejectors showing potent antiretroviral activity were developed, but early generations suffered from limited selectively and significant toxicity. Compounds with improved selectivity have been developed and are being explored as topical microbicide candidates. Several classes of molecules inhibiting the interaction of NCp7 with the viral nucleic acids have also been developed. Although small molecules would be more suited for drug development, most molecules selected by screening showed limited antiretroviral activity. Peptides and RNA aptamers appear to be more promising, but the mechanism of their antiretroviral activity remains elusive. Substantial and more concerted efforts are needed to further develop anti-HIV drugs targeting NCp7 and bring them to the clinic.
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Affiliation(s)
- Valérie Goldschmidt
- Laboratoire de Biophotonique et Pharmacologie, UMR-CNRS 7213, Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, 67401 Illkirch-Cedex, France
| | - Lisa M Miller Jenkins
- Laboratory of Cell Biology, NCI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hugues de Rocquigny
- Laboratoire de Biophotonique et Pharmacologie, UMR-CNRS 7213, Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, 67401 Illkirch-Cedex, France
| | - Jean-Luc Darlix
- LaboRetro, Unité de Virologie Humaine INSERM 758, Ecole Normale Supérieure de Lyon, 46 allée d’Italie, 69364 Lyon, France
| | - Yves Mély
- Laboratoire de Biophotonique et Pharmacologie, UMR-CNRS 7213, Faculté de Pharmacie, Université de Strasbourg, 74 route du Rhin, 67401 Illkirch-Cedex, France
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Peng Y, Song Y, Feng L, Ren J, Qu X. 7-Amino actinomycin D bound to single-stranded hairpin DNA enhanced by loop sequence-dependent luminescent Eu3+ and Tb3+ binding. J Inorg Biochem 2009; 103:1675-9. [DOI: 10.1016/j.jinorgbio.2009.09.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 09/15/2009] [Accepted: 09/16/2009] [Indexed: 01/10/2023]
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19
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Rhee WJ, Lee EH, Park TH. Expression of Bombyx mori 30Kc19 protein in Escherichia coli and its anti-apoptotic effect in Sf9 cell. BIOTECHNOL BIOPROC E 2009. [DOI: 10.1007/s12257-009-0081-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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20
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Lents NH, Wheeler LW, Baldassare JJ, Dynlacht BD. Identification and characterization of a novel Mdm2 splice variant acutely induced by the chemotherapeutic agents adriamycin and actinomycin D. Cell Cycle 2008; 7:1580-6. [PMID: 18469520 DOI: 10.4161/cc.7.11.5985] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mdm2, as the most important negative regulator of p53, plays an important homeostatic role in regulating cell division and the cellular response to DNA damage, oncogenic insult and other forms of cellular stress. We discovered that the DNA damaging agent adriamycin (doxorubicin) induces a novel aberrantly spliced Mdm2 mRNA which incorporates 108 bp of intronic sequence not normally found in the Mdm2 mature mRNA. Accordingly, we term this Mdm2 splice variant Mdm2(+108). Importantly, this insertion introduces in-frame nonsense codons, thus encoding a profoundly truncated mdm2 protein lacking the C-terminal RING finger domain and the E3 ubiquitin ligase activity. A wide range of pharmacological testing revealed that Mdm2(+108) is induced, in mouse and rat cells, in specific response to Adriamycin and actinomycin D, but not other modes of DNA damage. Meanwhile, antibodies against the N-terminal region of mdm2 reveal a marked reduction in detectable mdm2 protein upon Adriamycin treatment, while p53 accumulates to strikingly high levels. We thus conclude that this alternative spicing of Mdm2 may be an important mechanism to facilitate massive accumulation of p53 in response to genotoxic agents.
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Affiliation(s)
- Nathan H Lents
- Department of Sciences, John Jay College of Criminal Justice, The City University of New York, New York, New York 10019, USA.
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21
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Strand transfer events during HIV-1 reverse transcription. Virus Res 2008; 134:19-38. [PMID: 18279992 DOI: 10.1016/j.virusres.2007.12.017] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 12/19/2007] [Accepted: 12/20/2007] [Indexed: 11/20/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) and other retroviruses replicate through reverse transcription, a process in which the single stranded RNA of the viral genome is converted to a double stranded DNA. The virally encoded reverse transcriptase (RT) mediates reverse transcription through DNA polymerase and RNase H activities. Conversion of the plus strand RNA to plus/minus strand RNA/DNA hybrid involves a transfer of the growing DNA strand from one site on the genomic RNA to another. This is called minus strong-stop DNA transfer. Later synthesis of the second or plus DNA strand involves a second strand transfer, involving a similar mechanism as the minus strand transfer. A basic feature of the strand transfer mechanism is the use of the RT RNase H to remove segments of the RNA template strand from the growing DNA strand, freeing a single stranded region to anneal to the second site. Viral nucleocapsid protein (NC) functions to promote transfer by facilitating this strand exchange process. Two copies of the RNA genomes, sometimes non-identical, are co-packaged in the genomes of retroviruses. The properties of the reverse transcriptase allow a transfer of the growing DNA strand between these genomes to occur occasionally at any point during reverse transcription, producing recombinant viral progeny. Recombination promotes structural diversity of the virus that helps it to survive host immunity and drug therapy. Recombination strand transfer can be forced by a break in the template, or can occur at sites where folding structure of the template pauses the RT, allowing a concentration of RNase H cleavages that promote transfers. Transfer can be a simple one-step process, or can proceed by a complex multi-step invasion mechanism. In this latter process, the second RNA template interacts with the growing DNA strand well behind the DNA 3'-terminus. The newly formed RNA-DNA hybrid expands by branch migration and eventually catches the elongating DNA primer 3'-terminus to complete the transfer. Transfers are also promoted by interactions between the two RNA templates, which accelerate transfer by a proximity effect. Other details of the role of strand transfers in reverse transcription and the biochemical features of the transfer reaction are discussed.
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Iwatani Y, Chan DSB, Wang F, Stewart-Maynard K, Sugiura W, Gronenborn AM, Rouzina I, Williams MC, Musier-Forsyth K, Levin JG. Deaminase-independent inhibition of HIV-1 reverse transcription by APOBEC3G. Nucleic Acids Res 2007; 35:7096-108. [PMID: 17942420 PMCID: PMC2175344 DOI: 10.1093/nar/gkm750] [Citation(s) in RCA: 249] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
APOBEC3G (A3G), a host protein that inhibits HIV-1 reverse transcription and replication in the absence of Vif, displays cytidine deaminase and single-stranded (ss) nucleic acid binding activities. HIV-1 nucleocapsid protein (NC) also binds nucleic acids and has a unique property, nucleic acid chaperone activity, which is crucial for efficient reverse transcription. Here we report the interplay between A3G, NC and reverse transcriptase (RT) and the effect of highly purified A3G on individual reactions that occur during reverse transcription. We find that A3G did not affect the kinetics of NC-mediated annealing reactions, nor did it inhibit RNase H cleavage. In sharp contrast, A3G significantly inhibited all RT-catalyzed DNA elongation reactions with or without NC. In the case of (−) strong-stop DNA synthesis, the inhibition was independent of A3G's catalytic activity. Fluorescence anisotropy and single molecule DNA stretching analyses indicated that NC has a higher nucleic acid binding affinity than A3G, but more importantly, displays faster association/disassociation kinetics. RT binds to ssDNA with a much lower affinity than either NC or A3G. These data support a novel mechanism for deaminase-independent inhibition of reverse transcription that is determined by critical differences in the nucleic acid binding properties of A3G, NC and RT.
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Affiliation(s)
- Yasumasa Iwatani
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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23
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Wu T, Heilman-Miller SL, Levin JG. Effects of nucleic acid local structure and magnesium ions on minus-strand transfer mediated by the nucleic acid chaperone activity of HIV-1 nucleocapsid protein. Nucleic Acids Res 2007; 35:3974-87. [PMID: 17553835 PMCID: PMC1919501 DOI: 10.1093/nar/gkm375] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
HIV-1 nucleocapsid protein (NC) is a nucleic acid chaperone, which is required for highly specific and efficient reverse transcription. Here, we demonstrate that local structure of acceptor RNA at a potential nucleation site, rather than overall thermodynamic stability, is a critical determinant for the minus-strand transfer step (annealing of acceptor RNA to (−) strong-stop DNA followed by reverse transcriptase (RT)-catalyzed DNA extension). In our system, destabilization of a stem-loop structure at the 5′ end of the transactivation response element (TAR) in a 70-nt RNA acceptor (RNA 70) appears to be the major nucleation pathway. Using a mutational approach, we show that when the acceptor has a weak local structure, NC has little or no effect. In this case, the efficiencies of both annealing and strand transfer reactions are similar. However, when NC is required to destabilize local structure in acceptor RNA, the efficiency of annealing is significantly higher than that of strand transfer. Consistent with this result, we find that Mg2+ (required for RT activity) inhibits NC-catalyzed annealing. This suggests that Mg2+ competes with NC for binding to the nucleic acid substrates. Collectively, our findings provide new insights into the mechanism of NC-dependent and -independent minus-strand transfer.
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Affiliation(s)
| | | | - Judith G. Levin
- *To whom correspondence should be addressed. +1 301 496 1970+1 301 496 0243
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Imamichi T, Conrads TP, Zhou M, Liu Y, Adelsberger JW, Veenstra TD, Lane HC. A transcription inhibitor, actinomycin D, enhances HIV-1 replication through an interleukin-6-dependent pathway. J Acquir Immune Defic Syndr 2006; 40:388-97. [PMID: 16280692 DOI: 10.1097/01.qai.0000179466.25700.2f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We previously demonstrated that Actinomycin D (ActD) enhanced HIV-1 replication in the MT-2 cell, a human T-cell leukemia virus type-1-infected cell line. The MT-2 cell is known to produce multiple cytokines spontaneously. In this study, we investigated the impact of ActD on the cytokine production from MT-2 cells and HIV-1 replication in a latently infected cell line, U1. MT-2 cells were pulse-treated with 0 or 200 nM of ActD, and culture supernatants were collected 3 days after incubation. Supernatants from untreated cells (Sup0) induced HIV-1 replication by 150-fold in U1 cells. Culture supernatants from ActD-treated cells (Sup200) enhanced HIV-1 replication by 1200-fold. A combination of a sequential chromatographic approach and mass spectrometric analysis identified that the HIV-inducing factors in Sup200 were interleukin (IL)-6 and tumor necrosis factor (TNF)-beta. Quantitative analysis revealed that ActD treatment increased the concentration of IL-6 in Sup200 by 600% compared with that in Sup0 but decreased the amount of TNFbeta in Sup200 by 85%. Northern blot analysis showed that ActD treatment increased IL-6 transcripts; however, no change was seen in TNFbeta transcripts. These results suggest that ActD induces replication of HIV-1 through modulation of cytokine production.
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Affiliation(s)
- Tomozumi Imamichi
- Laboratory of Human Retrovirology, Science Applications International Corporation (SAIC)-Frederick, Frederick, MD 21702-1201, USA.
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25
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Levin JG, Guo J, Rouzina I, Musier-Forsyth K. Nucleic acid chaperone activity of HIV-1 nucleocapsid protein: critical role in reverse transcription and molecular mechanism. ACTA ACUST UNITED AC 2006; 80:217-86. [PMID: 16164976 DOI: 10.1016/s0079-6603(05)80006-6] [Citation(s) in RCA: 256] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Judith G Levin
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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26
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Godet J, de Rocquigny H, Raja C, Glasser N, Ficheux D, Darlix JL, Mély Y. During the early phase of HIV-1 DNA synthesis, nucleocapsid protein directs hybridization of the TAR complementary sequences via the ends of their double-stranded stem. J Mol Biol 2005; 356:1180-92. [PMID: 16406407 DOI: 10.1016/j.jmb.2005.12.038] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 12/07/2005] [Accepted: 12/12/2005] [Indexed: 11/22/2022]
Abstract
Reverse transcription of HIV-1 genomic RNA requires two obligatory strand transfers. During the first strand transfer reaction, the minus strand strong-stop DNA (ss-cDNA) is transferred by hybridization of complementary sequences located at the 3' ends of the ss-cDNA and genomic template, respectively. In HIV-1, the major components of ss-cDNA transfer are the terminally redundant structured TAR elements and the nucleocapsid protein NCp7, which actively chaperones the hybridization of cTAR DNA to TAR. In the present study, we investigated the annealing kinetics of TAR with fluorescently labelled cTAR derivatives both in the absence and in the presence of NC(12-55), a peptide that contains the finger and C-terminal domains of NCp7. The annealing of TAR with cTAR involves two second-order kinetic components that are activated by at least two orders of magnitude by NC(12-55). The NC-promoted activation of cTAR-TAR annealing was correlated with its ability to destabilize the lower half of TAR stem, in order to generate the single-stranded complementary regions for nucleating the duplex structures. The two kinetics components have been assigned to two different pathways. The rapid one does not lead to extended duplex formation but is associated with a limited annealing of the terminal bases of cTAR to TAR. On the other hand, extended duplex formation follows a slower pathway that is limited kinetically by the nucleation of residues located mainly within the central double-stranded segment of both cTAR and TAR stems. An alternative mechanism involving an interaction through TAR and cTAR loops has been observed but is a minor pathway in the present conditions.
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Affiliation(s)
- Julien Godet
- Photophysique des interactions moléculaires, UMR 7175 CNRS, Institut Gilbert Laustriat, Faculté de Pharmacie, Université Louis Pasteur, Strasbourg 1, 74, Route du Rhin, 67401 Illkirch Cedex, France
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27
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Kurosawa K, Bui VP, VanEssendelft JL, Willis LB, Lessard PA, Ghiviriga I, Sambandan TG, Rha CK, Sinskey AJ. Characterization of Streptomyces MITKK-103, a newly isolated actinomycin X2-producer. Appl Microbiol Biotechnol 2005; 72:145-154. [PMID: 16374634 DOI: 10.1007/s00253-005-0240-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 10/21/2005] [Accepted: 11/01/2005] [Indexed: 11/29/2022]
Abstract
A new actinomycete strain designated MITKK-103 was isolated from the soil of a flowerpot using a humic acid agar medium. The newly isolated strain was able to produce a large amount of actinomycin X2 even under nonoptimized growing conditions and serves as a promising source of this antibiotic. Actinomycin X2 has higher cytotoxicity toward cultured human leukemia (HL-60) cells than does actinomycin D, and it induces cell death via apoptosis. A nearly complete 16S ribosomal DNA (rDNA) sequence from the isolate was determined and found to have high identity (98.5-100%) with Streptomyces galbus, Streptomyces griseofuscus, and Streptomyces padanus, indicating that MITKK-103 belongs to the genus Streptomyces. The isolate clustered with species belonging to the S. padanus clade in a 16S-rDNA-based phylogenetic tree and showed 75% overall homology to S. padanus ATCC 25646 in DNA-DNA relatedness analysis. Although the growth of the isolate was somewhat different from the three species mentioned, the strain MITKK-103 most closely resembles S. padanus on the basis of the morphological and phenotypic characteristics, phylogenetic analysis, and genotypic data. As such, this is the first report of a strain of S. padanus capable of producing actinomycins.
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MESH Headings
- Bacterial Typing Techniques
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Dactinomycin/analogs & derivatives
- Dactinomycin/biosynthesis
- Dactinomycin/toxicity
- HL-60 Cells
- Humans
- Microscopy, Electron, Scanning
- Molecular Sequence Data
- Nucleic Acid Hybridization
- Phylogeny
- Pigments, Biological/biosynthesis
- RNA, Ribosomal, 16S/genetics
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
- Soil Microbiology
- Streptomyces/classification
- Streptomyces/isolation & purification
- Streptomyces/metabolism
- Streptomyces/ultrastructure
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Affiliation(s)
- K Kurosawa
- Department of Biology, Building 68-370, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - V P Bui
- Department of Biology, Building 68-370, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - J L VanEssendelft
- Department of Biology, Building 68-370, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - L B Willis
- Department of Biology, Building 68-370, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - P A Lessard
- Department of Biology, Building 68-370, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - I Ghiviriga
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - T G Sambandan
- Biomaterials Science and Engineering Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - C K Rha
- Biomaterials Science and Engineering Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - A J Sinskey
- Department of Biology, Building 68-370, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
- Department of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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28
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Egelé C, Schaub E, Piémont E, de Rocquigny H, Mély Y. Investigation by fluorescence correlation spectroscopy of the chaperoning interactions of HIV-1 nucleocapsid protein with the viral DNA initiation sequences. C R Biol 2005; 328:1041-51. [PMID: 16314282 DOI: 10.1016/j.crvi.2005.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 05/26/2005] [Accepted: 07/27/2005] [Indexed: 11/23/2022]
Abstract
HIV-1 nucleocapsid protein (NC) exhibits nucleic acid chaperone properties that are important during reverse transcription. Herein, we review and extend our recent investigation by fluorescence correlation spectroscopy (FCS) of the NC chaperone activity on the primer binding site sequences (PBS) of the (-) and (+) DNA strands, which are involved in the second strand transfer during reverse transcription. In the absence of NC, the PBS stem-loops exhibited a fraying limited to the terminal G-C base pair. The kinetics of fraying were significantly activated by NC, a feature that may favour (-)PBS/(+)PBS annealing during the second strand transfer. In addition, NC was found to promote the formation of PBS kissing homodimers through interaction between the loops. These kissing complexes may favour secondary contacts between viral sequences and thus, promote recombination and viral diversity.
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Affiliation(s)
- Caroline Egelé
- Laboratoire de pharmacologie et physico-chimie des interactions cellulaires et moléculaires, UMR 7034, CNRS, faculté de pharmacie, université Louis-Pasteur, Strasbourg-1, 74, route du Rhin, 67401 Illkirch cedex, France
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29
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Liu HW, Cosa G, Landes CF, Zeng Y, Kovaleski BJ, Mullen DG, Barany G, Musier-Forsyth K, Barbara PF. Single-molecule FRET studies of important intermediates in the nucleocapsid-protein-chaperoned minus-strand transfer step in HIV-1 reverse transcription. Biophys J 2005; 89:3470-9. [PMID: 16100256 PMCID: PMC1366842 DOI: 10.1529/biophysj.105.065326] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The minus-strand transfer step of HIV-1 reverse transcription is chaperoned by the nucleocapsid protein (NC), which has been shown to facilitate the annealing between the transactivation response element (TAR) RNA and complementary TAR DNA stem-loop structures. In this work, potential intermediates in the mechanism of NC-chaperoned TAR DNA/TAR RNA annealing have been examined using single-molecule fluorescence resonance energy transfer. The interaction between TAR DNA and various DNA oligonucleotides designed to mimic the initial annealing step was monitored to capture potential intermediates along the reaction pathway. Two possible mechanisms of annealing were examined, namely nucleation through the 3'/5' termini, termed the "zipper" complex, or nucleation through the hairpin loops in a "kissing" complex. Intermediates associated with both mechanisms were observed in the presence of NC, and the kinetics of formation of these intermediates were also measured. Thus, the single-molecule experiments support the notion that NC-assisted annealing of TAR DNA:TAR RNA may occur through multiple pathways.
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Affiliation(s)
- Hsiao-Wei Liu
- Department of Chemistry and Biochemistry, Center for Nano and Molecular Science and Technology, University of Texas, Austin, TX 78712, USA
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30
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Beltz H, Clauss C, Piémont E, Ficheux D, Gorelick RJ, Roques B, Gabus C, Darlix JL, de Rocquigny H, Mély Y. Structural determinants of HIV-1 nucleocapsid protein for cTAR DNA binding and destabilization, and correlation with inhibition of self-primed DNA synthesis. J Mol Biol 2005; 348:1113-26. [PMID: 15854648 DOI: 10.1016/j.jmb.2005.02.042] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Revised: 02/17/2005] [Accepted: 02/17/2005] [Indexed: 11/30/2022]
Abstract
The nucleocapsid protein (NC) of human immunodeficiency virus type 1 (HIV-1) is formed of two highly conserved CCHC zinc fingers flanked by small basic domains. NC is required for the two obligatory strand transfers in viral DNA synthesis through its nucleic acid chaperoning properties. The first DNA strand transfer relies on NC's ability to bind and destabilize the secondary structure of complementary transactivation response region (cTAR) DNA, to inhibit self-priming, and to promote the annealing of cTAR to TAR RNA. To further investigate NC chaperone properties, our aim was to identify by fluorescence spectroscopy and gel electrophoresis, the NC structural determinants for cTAR binding and destabilization, and for the inhibition of self-primed DNA synthesis on a model system using a series of NC mutants and HIV-1 reverse transcriptase. NC destabilization and self-priming inhibition properties were found to be supported by the two fingers in their proper context and the basic (29)RAPRKKG(35) linker. The strict requirement of the native proximal finger suggests that its hydrophobic platform (Val13, Phe16, Thr24 and Ala25) is crucial for binding, destabilization and inhibition of self-priming. In contrast, only partial folding of the distal finger is required, probably for presenting the Trp37 residue in an appropriate orientation. Also, Trp37 and the hydrophobic residues of the proximal finger appear to be essential for the propagation of the melting from the cTAR ends up to the middle of the stem. Finally, both N-terminal and C-terminal basic domains contribute to cTAR binding but not to its destabilization.
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Affiliation(s)
- Hervé Beltz
- Laboratoire de Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR 7034 CNRS, Faculté de Pharmacie, Université Louis Pasteur, Strasbourg 1, 74, Route du Rhin, 67401 Illkirch Cedex, France
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31
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Chen Y, Balakrishnan M, Roques BP, Bambara RA. Acceptor RNA cleavage profile supports an invasion mechanism for HIV-1 minus strand transfer. J Biol Chem 2005; 280:14443-52. [PMID: 15657044 DOI: 10.1074/jbc.m412190200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously proposed that HIV-1 minus strand transfer occurs by an acceptor invasion-initiated multi-step mechanism. During synthesis of minus strong stop DNA, reverse transcriptase (RT) transiently pauses at the base of TAR before continuing synthesis. Pausing promotes RT-RNase H cleavage of the donor RNA, exposing regions of the cDNA. The acceptor RNA then invades at these locations to interact with the minus strong stop DNA. Whereas primer extension continues on the donor RNA, the cDNA-acceptor hybrid expands by branch migration until transfer of the primer terminus is completed. We present results here showing that the interaction of the acceptor RNA and the cDNA can be determined by examining the time-dependent cleavage of the acceptor RNA by RNase H. Our approach utilizes a combination of RT-RNase H and Escherichia coli RNase H to allow assessment of acceptor-cDNA interactions at high sensitivity. Results show an initial interaction of the acceptor RNA with cDNA at the base of TAR. We observe a time-dependent shift in RNase H susceptibility along the length of the acceptor toward the 5' end, suggesting hybrid propagation from the initial invasion point. Control experiments validate that the RNase H cleavage profile represents the formation and expansion of the acceptor-DNA interaction and that the process is promoted by the nucleocapsid. Observations with this new approach lend additional support to the proposed multistep transfer mechanism.
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Affiliation(s)
- Yan Chen
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, New York 14642, USA
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32
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Egelé C, Schaub E, Ramalanjaona N, Piémont E, Ficheux D, Roques B, Darlix JL, Mély Y. HIV-1 nucleocapsid protein binds to the viral DNA initiation sequences and chaperones their kissing interactions. J Mol Biol 2004; 342:453-66. [PMID: 15327946 DOI: 10.1016/j.jmb.2004.07.059] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Accepted: 07/19/2004] [Indexed: 11/17/2022]
Abstract
The chaperone properties of the human immunodeficiency virus type 1 (HIV-1) nucleocapsid protein (NC) are required for the two obligatory strand transfer reactions occurring during viral DNA synthesis. The second strand transfer relies on the destabilization and the subsequent annealing of the primer binding site sequences (PBS) at the 3' end of the (-) and (+) DNA strands. To characterize the binding and chaperone properties of NC on the (-)PBS and (+)PBS sequences, we monitored by steady-state and time-resolved fluorescence spectroscopy as well as by fluorescence correlation spectroscopy the interaction of NC with wild type and mutant oligonucleotides corresponding to the (-)PBS and (+)PBS hairpins. NC was found to bind with high affinity to the loop, the stem and the single-stranded protruding sequence of both PBS sequences. NC induces only a limited destabilization of the secondary structure of both sequences, activating the transient melting of the stem only during its "breathing" period. This probably results from the high stability of the PBS due to the four G-C pairs in the stem. In contrast, NC directs the formation of "kissing" homodimers efficiently for both (-)PBS and (+)PBS sequences. Salt-induced dimerization and mutations in the (-)PBS sequence suggest that these homodimers may be stabilized by two intermolecular G-C Watson-Crick base-pairs between the partly self-complementary loops. The propensity of NC to promote the dimerization of partly complementary sequences may favor secondary contacts between viral sequences and thus, recombination and viral diversity.
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Affiliation(s)
- Caroline Egelé
- Laboratoire de Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR 7034 CNRS, Faculté de Pharmacie, Université Louis Pasteur, Strasbourg 1, 74, Route du Rhin, 67401 Illkirch Cedex, France
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33
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Heilman-Miller SL, Wu T, Levin JG. Alteration of nucleic acid structure and stability modulates the efficiency of minus-strand transfer mediated by the HIV-1 nucleocapsid protein. J Biol Chem 2004; 279:44154-65. [PMID: 15271979 DOI: 10.1074/jbc.m401646200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During human immunodeficiency virus type 1 minus-strand transfer, the nucleocapsid protein (NC) facilitates annealing of the complementary repeat regions at the 3'-ends of acceptor RNA and minus-strand strong-stop DNA ((-) SSDNA). In addition, NC destabilizes the highly structured complementary trans-activation response element (TAR) stem-loop (TAR DNA) at the 3'-end of (-) SSDNA and inhibits TAR-induced self-priming, a dead-end reaction that competes with minus-strand transfer. To investigate the relationship between nucleic acid secondary structure and NC function, a series of truncated (-) SSDNA and acceptor RNA constructs were used to assay minus-strand transfer and self-priming in vitro. The results were correlated with extensive enzymatic probing and mFold analysis. As the length of (-) SSDNA was decreased, self-priming increased and was highest when the DNA contained little more than TAR DNA, even if NC and acceptor were both present; in contrast, truncations within TAR DNA led to a striking reduction or elimination of self-priming. However, destabilization of TAR DNA was not sufficient for successful strand transfer: the stability of acceptor RNA was also crucial, and little or no strand transfer occurred if the RNA was highly stable. Significantly, NC may not be required for in vitro strand transfer if (-) SSDNA and acceptor RNA are small, relatively unstructured molecules with low thermodynamic stabilities. Collectively, these findings demonstrate that for efficient NC-mediated minus-strand transfer, a delicate thermodynamic balance between the RNA and DNA reactants must be maintained.
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Affiliation(s)
- Susan L Heilman-Miller
- Laboratory of Molecular Genetics, NICHD, National Institutes of Health, Bethesda, Maryland 20892-2780, USA
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34
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Beltz H, Piémont E, Schaub E, Ficheux D, Roques B, Darlix JL, Mély Y. Role of the structure of the top half of HIV-1 cTAR DNA on the nucleic acid destabilizing activity of the nucleocapsid protein NCp7. J Mol Biol 2004; 338:711-23. [PMID: 15099739 DOI: 10.1016/j.jmb.2004.03.019] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Revised: 03/01/2004] [Accepted: 03/01/2004] [Indexed: 11/27/2022]
Abstract
The viral nucleic acid chaperone protein NCp7 of HIV-1 assists the two obligatory strand transfers required for the conversion of the genomic RNA into double-stranded DNA by reverse transcriptase. The first strand transfer necessitates the annealing of the early product of cDNA synthesis, the minus strand strong stop DNA (ss-cDNA) to the 3' end of the genomic RNA. The hybridization reaction involves regions containing imperfect stem-loop (SL) structures, namely the TAR RNA at the 3' end of the genomic RNA and the complementary sequence cTAR at the 3' end of ss-cDNA. To pursue the characterization of the interaction between NCp7 and cTAR DNA, we investigated by absorbance, steady-state and time-resolved fluorescence spectroscopy, the interaction of NCp7 with wild-type and mutated DNAs representing the top half of cTAR. NCp7 was found to activate the transient melting of this cTAR DNA structure but less efficiently than that of cTAR lower half. The NCp7-induced destabilization of cTAR top half is dependent upon the three nucleotides bulging out of the stem, which thus represent a melting initiation site. In contrast, despite its ability to bind NCp7, the top loop does not play any significant role in NCp7-mediated melting. Thermodynamic data further suggest that NCp7-mediated destabilization of this cTAR structure correlates with the free energy changes afforded by destabilizing motifs like loops and bulges within the SL secondary structure. Interestingly, since NCp7 melts only short double-stranded sequences, destabilizing motifs need to be regularly positioned along the genomic sequence in order to promote strand transfer and thus genetic recombination during proviral DNA synthesis.
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Affiliation(s)
- Hervé Beltz
- UMR 7034 CNRS, Faculté de Pharmacie, Université Louis Pasteur, Strasbourg 1, 74 Route du Rhin, 67401 Illkirch Cedex, France
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35
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Chen FM, Sha F, Chin KH, Chou SH. The nature of actinomycin D binding to d(AACCAXYG) sequence motifs. Nucleic Acids Res 2004; 32:271-7. [PMID: 14715925 PMCID: PMC373288 DOI: 10.1093/nar/gkh178] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Earlier studies by others had indicated that actinomycin D (ACTD) binds well to d(AACCATAG) and the end sequence TAG-3' is essential for its strong binding. In an effort to verify these assertions and to uncover other possible strong ACTD binding sequences as well as to elucidate the nature of their binding, systematic studies have been carried out with oligomers of d(AACCAXYG) sequence motifs, where X and Y can be any DNA base. The results indicate that in addition to TAG-3', oligomers ending with XAG-3' and XCG-3' all provide binding constants > or =1 x 10(7) M(-1) and even sequences ending with XTG-3' and XGG-3' exhibit binding affinities in the range 1-8 x 10(6) M(-1). The nature of the strong ACTD affinity of the sequences d(A1A2C3C4A5X6Y7G8) was delineated via comparative binding studies of d(AACCAAAG), d(AGCCAAAG) and their base substituted derivatives. Two binding modes are proposed to coexist, with the major component consisting of the 3'-terminus G base folding back to base pair with C4 and the ACTD inserting at A2C3C4 by looping out the C3 while both faces of the chromophore are stacked by A and G bases, respectively. The minor mode is for the G to base pair with C3 and to have the same A/chromophore/G stacking but without a looped out base. These assertions are supported by induced circular dichroic and fluorescence spectral measurements.
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Affiliation(s)
- Fu-Ming Chen
- Department of Chemistry, Tennessee State University, Nashville, TN 37209-1561, USA.
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36
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Chen Y, Balakrishnan M, Roques BP, Bambara RA. Steps of the acceptor invasion mechanism for HIV-1 minus strand strong stop transfer. J Biol Chem 2003; 278:38368-75. [PMID: 12878597 DOI: 10.1074/jbc.m305700200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Minus strand strong stop transfer is obligatory for completion of HIV-1 minus strand synthesis. We previously showed evidence for an acceptor invasion-initiated mechanism for minus strand transfer. In the present study, we examined the major acceptor invasion initiation site using a minus strand transfer system in vitro, containing the 97-nucleotide full-length R region. A series of DNA oligonucleotides complementary to different regions of the cDNA was designed to interfere with transfer. Oligomers covering the region around the base of the TAR hairpin were most effective in inhibiting transfer, suggesting that the hairpin base is a preferred site for acceptor invasion. The strong pausing of reverse transcriptase at the base of the TAR and the concomitant RNase H cleavages 10-19 nucleotides behind the pause site correlated with the location of the invasion site. Oligomers closer to the 5'-end of R also inhibited transfer, though less effectively, presumably by blocking strand exchange and branch migration. We propose that pausing of reverse transcriptase at the base of TAR increases RNase H cleavages, creating gaps for acceptor invasion and transfer initiation. Strand exchange then propagates by branch migration, displacing the fragmented donor RNA, including the fragment at the 5' terminus. The primer terminus switches to the acceptor, completing the transfer. Nucleocapsid (NC) protein stimulated transfer efficiency by 5-7-fold. NC enhanced RNase H cleavages close to the TAR base, creating more effective invasion sites for efficient transfer. Most likely, NC also stimulates transfer by promoting strand exchange invasion and branch migration.
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Affiliation(s)
- Yan Chen
- Department of Biochemistry and Biophysics, University of Rochester, New York 14642, USA
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37
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Beltz H, Azoulay J, Bernacchi S, Clamme JP, Ficheux D, Roques B, Darlix JL, Mély Y. Impact of the terminal bulges of HIV-1 cTAR DNA on its stability and the destabilizing activity of the nucleocapsid protein NCp7. J Mol Biol 2003; 328:95-108. [PMID: 12684000 DOI: 10.1016/s0022-2836(03)00244-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Reverse transcription of HIV-1 genomic RNA to double-stranded DNA by reverse transcriptase (RT) is a critical step in HIV-1 replication. This process relies on two viral proteins, the RT enzyme and nucleocapsid protein NCp7 that has well documented nucleic acid chaperone properties. At the beginning of the linear DNA synthesis, the newly made minus-strand strong-stop DNA ((-)ssDNA) is transferred to the 3'end of the genomic RNA by means of an hybridization reaction between transactivation response element (TAR) RNA and cTAR DNA sequences. Since both TAR sequences exhibit stable hairpin structures, NCp7 needs to destabilize the TAR structures in order to chaperone their hybridization. To further characterize the relationships between TAR stability and NC-mediated destabilization, the role of the A(49) and G(52) bulged residues in cTAR DNA stability was investigated. The stability of cTAR and mutants where one or the two terminal bulges were replaced by base-pairs as well as the NCp7-mediated destabilization of these cTAR sequences were examined. Thermodynamic data indicate that the two bulges cooperatively destabilize cTAR by reducing the stacking interactions between the bases. This causes a free energy change of about 6.4 kcal/mol and seems to be critical for NC activity. Time-resolved fluorescence data of doubly labelled cTAR derivatives suggest that NC-mediated melting of cTAR ends propagates up to the 10C.A(44) mismatch or T(40) bulge. Fluorescence correlation spectroscopy using two-photon excitation was also used to monitor cTAR ends fraying by NC. Results show that NC causes a very significant increase of cTAR ends fraying, probably limited to the terminal base-pair in the case of cTAR mutants. Since the TAR RNA and cTAR DNA bulges or mismatches appear well conserved among all HIV-1 strains, the present data support the notion of a co-evolutionary relationship between TAR and NC activity.
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Affiliation(s)
- Hervé Beltz
- Laboratoire de Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR 7034 CNRS, Faculté de Pharmacie, Université Louis Pasteur, Strasbourg 1, 74, Route du Rhin, 67401 Illkirch Cedex, France
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38
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Chen Y, Balakrishnan M, Roques BP, Fay PJ, Bambara RA. Mechanism of minus strand strong stop transfer in HIV-1 reverse transcription. J Biol Chem 2003; 278:8006-17. [PMID: 12499370 DOI: 10.1074/jbc.m210959200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retrovirus minus strand strong stop transfer (minus strand transfer) requires reverse transcriptase-associated RNase H, R sequence homology, and viral nucleocapsid protein. The minus strand transfer mechanism in human immunodeficiency virus-1 was examined in vitro with purified protein and substrates. Blocking donor RNA 5'-end cleavage inhibited transfers when template homology was 19 nucleotides (nt) or less. Cleavage of the donor 5'-end occurred prior to formation of transfer products. This suggests that when template homology is short, transfer occurs through a primer terminus switch-initiated mechanism, which requires cleavage of the donor 5' terminus. On templates with 26-nt and longer homology, transfer occurred before cleavage of the donor 5' terminus. Transfer was unaffected when donor 5'-end cleavages were blocked but was reduced when internal cleavages within the donor were restricted. Based on the overall data, we conclude that in human immunodeficiency virus-1, which contains a 97-nt R sequence, minus strand transfer occurs through an acceptor invasion-initiated mechanism. Transfer is initiated at internal regions of the homologous R sequence without requiring cleavage at the donor 5'-end. The acceptor invades at gaps created by reverse transcriptase-RNase H in the donor-cDNA hybrid. The fragmented donor is eventually strand-displaced by the acceptor, completing the transfer.
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Affiliation(s)
- Yan Chen
- Department of Biochemistry and Biophysics, University of Rochester, New York 14642, USA
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39
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Hong MK, Harbron EJ, O'Connor DB, Guo J, Barbara PF, Levin JG, Musier-Forsyth K. Nucleic acid conformational changes essential for HIV-1 nucleocapsid protein-mediated inhibition of self-priming in minus-strand transfer. J Mol Biol 2003; 325:1-10. [PMID: 12473448 DOI: 10.1016/s0022-2836(02)01177-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Reverse transcription of the HIV-1 genome is a complex multi-step process. HIV-1 nucleocapsid protein (NC) is a nucleic acid chaperone protein that has been shown to greatly facilitate the nucleic acid rearrangements that precede the minus-strand transfer step in reverse transcription. NC destabilizes the highly structured transactivation response region (TAR) present in the R region of the RNA genome, as well as a complementary hairpin structure ("TAR DNA") at the 3'-end of the newly synthesized minus-strand strong-stop DNA ((-) SSDNA). Melting of the latter structure inhibits a self-priming (SP) reaction that competes with the strand transfer reaction. In an in vitro minus-strand transfer system consisting of a (-) SSDNA mimic and a TAR-containing acceptor RNA molecule, we find that when both nucleic acids are present, NC facilitates formation of the transfer product and the SP reaction is greatly reduced. In contrast, in the absence of the acceptor RNA, NC has only a small inhibitory effect on the SP reaction. To further investigate NC-mediated inhibition of SP, we developed a FRET-based assay that allows us to directly monitor conformational changes in the TAR DNA structure upon NC binding. Although the majority ( approximately 71%) of the TAR DNA molecules assume a folded hairpin conformation in the absence of NC, two minor "semi-folded" and "unfolded" populations are also observed. Upon NC binding to the TAR DNA alone, we observe a modest shift in the population towards the less-folded states. In the presence of the RNA acceptor molecule, NC binding to TAR DNA results in a shift of the majority of molecules to the unfolded state. These measurements help to explain why acceptor RNA is required for significant inhibition of the SP reaction by NC, and support the hypothesis that NC-mediated annealing of nucleic acids is a concerted process wherein the unwinding step occurs in synchrony with hybridization.
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Affiliation(s)
- Minh K Hong
- Department of Chemistry, University of Minnesota, 207 Pleasant Street S.E., Minneapolis, MN 55455-0431, USA
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40
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Imamichi T, Murphy MA, Adelsberger JW, Yang J, Watkins CM, Berg SC, Baseler MW, Lempicki RA, Guo J, Levin JG, Lane HC. Actinomycin D induces high-level resistance to thymidine analogs in replication of human immunodeficiency virus type 1 by interfering with host cell thymidine kinase expression. J Virol 2003; 77:1011-20. [PMID: 12502817 PMCID: PMC140776 DOI: 10.1128/jvi.77.2.1011-1020.2003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Actinomycin D (ActD) is a transcription inhibitor and has been used in the treatment of certain forms of cancer. ActD has been reported to be a potential inhibitor of human immunodeficiency virus type 1 (HIV-1) replication due to its ability to inhibit reverse transcription. In contrast to what was expected, low concentrations of ActD (1 to 10 nM) upregulated HIV-1 replication 8- to 10-fold in MT-2 cells and had no effect on HIV-2 replication or on HIV-1 replication in MT-4, Jurkat, or peripheral blood mononuclear cells. The upregulation of HIV-1 replication was associated with an increase in HIV-1 transcription and a decrease in CD4 and CXCR4 expression. To further evaluate the effects of ActD on emergence of drug resistance in HIV-1 replication, a series of drug resistance assays were performed. Of interest, treatment of MT-2 cells with ActD also led to a high level of resistance to thymidine analogs (>1,000-fold increase in resistance to zidovudine and >250-fold to stavudine) but not to other nucleoside reverse transcriptases (RT), nonnucleoside RT, or protease inhibitors. This resistance appeared to be due to a suppression of host cell thymidine kinase-1 (TK-1) expression. These results indicate that ActD leads to a novel form of thymidine analog resistance by suppressing host cell TK-1 expression. These results suggest that administration of combination drugs to HIV-1-infected patients may induce resistance to antiretroviral compounds via a modification of cellular factors.
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Affiliation(s)
- Tomozumi Imamichi
- Laboratory of Molecular Retrovirology, Clinical Services Program, Science Applications International Corporation-Frederick Inc., National Cancer Institute-Frederick, Maryland 21702, USA.
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41
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Wisniewski M, Chen Y, Balakrishnan M, Palaniappan C, Roques BP, Fay PJ, Bambara RA. Substrate requirements for secondary cleavage by HIV-1 reverse transcriptase RNase H. J Biol Chem 2002; 277:28400-10. [PMID: 12023278 DOI: 10.1074/jbc.m201645200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During and after minus-strand DNA synthesis, human immunodeficiency virus 1 (HIV-1) reverse transcriptase (RT) degrades the RNA genome. To remove RNA left after polymerization, the RT aligns to cut 18 nucleotides in from the 5' RNA end. The enzyme then repositions, making a secondary cut 8 nucleotides from the RNA 5' end. Transfer of the minus strong stop DNA during viral replication requires cleavage of template RNA. Removal of the terminal RNA segment is a special case because the RNA-DNA hybrid forms a blunt end, shown previously to resist cleavage when tested in vitro. We show here that the structure of the substrate extending beyond the RNA 5' end is an important determinant of cleavage efficiency. A short single-stranded DNA extension greatly stimulated the secondary cleavage. Annealing an RNA segment to the DNA extension was even more stimulatory. Recessing the DNA from a blunt end by even one nucleotide caused the RT to reorient its binding, preventing secondary cleavage. The presence of the cap at the 5' end of the viral RNA did not improve the efficiency of secondary cleavage. However, NC protein greatly facilitated the secondary cut on the blunt-ended substrate, suggesting that NC compensates for the unfavorable substrate structure.
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Affiliation(s)
- Michele Wisniewski
- Department of Biochemistry and Biophysics and the Cancer Center, University of Rochester, Rochester, New York 14642, USA
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42
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Rhee WJ, Kim EJ, Park TH. Silkworm hemolymph as a potent inhibitor of apoptosis in Sf9 cells. Biochem Biophys Res Commun 2002; 295:779-83. [PMID: 12127960 DOI: 10.1016/s0006-291x(02)00746-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have previously shown that silkworm hemolymph exhibits anti-apoptotic activity against baculovirus-induced Sf9 cell apoptosis. In this study, using various chemical inducers, such as actinomycin D, camptothecin, and staurosporine, we found that silkworm hemolymph inhibits insect cell apoptosis induced not only by baculovirus but also by chemical inducers. This indicates that silkworm hemolymph contains anti-apoptotic components that work directly in insect cell apoptosis without any booster expression of baculoviral genes. With the analysis of Sf-caspase-1 activity, it was found that the inhibitory effect of silkworm hemolymph works in a further upstream step than the Sf-caspase-1 activation step.
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Affiliation(s)
- Won Jong Rhee
- School of Chemical Engineering and Institute of Chemical Processes, Seoul National University, Kwanak-Gu Shilim-Dong San 56-1, Seoul, Republic of Korea
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43
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Guo J, Wu T, Kane BF, Johnson DG, Henderson LE, Gorelick RJ, Levin JG. Subtle alterations of the native zinc finger structures have dramatic effects on the nucleic acid chaperone activity of human immunodeficiency virus type 1 nucleocapsid protein. J Virol 2002; 76:4370-8. [PMID: 11932404 PMCID: PMC155087 DOI: 10.1128/jvi.76.9.4370-4378.2002] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleocapsid protein (NC) of human immunodeficiency virus type 1 has two zinc fingers, each containing the invariant CCHC zinc-binding motif; however, the surrounding amino acid context is not identical in the two fingers. Recently, we demonstrated that zinc coordination is required when NC unfolds complex secondary structures in RNA and DNA minus- and plus-strand transfer intermediates; this property of NC reflects its nucleic acid chaperone activity. Here we have analyzed the chaperone activities of mutants having substitutions of alternative zinc-coordinating residues, i.e., CCHH or CCCC, for the wild-type CCHC motif. We also investigated the activities of mutants that retain the CCHC motifs but have mutations that exchange or duplicate the zinc fingers (mutants 1-1, 2-1, and 2-2); these changes affect amino acid context. Our results indicate that in general, for optimal activity in an assay that measures stimulation of minus-strand transfer and inhibition of nonspecific self-priming, the CCHC motif in the zinc fingers cannot be replaced by CCHH or CCCC and the amino acid context of the fingers must be conserved. Context changes also reduce the ability of NC to facilitate primer removal in plus-strand transfer. In addition, we found that the first finger is a more crucial determinant of nucleic acid chaperone activity than the second finger. Interestingly, comparison of the in vitro results with earlier in vivo replication data raises the possibility that NC may adopt multiple conformations that are responsible for different NC functions during virus replication.
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Affiliation(s)
- Jianhui Guo
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA
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44
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Stefanelli CC, Castilho JG, Botelho MVJ, Linhares REC, Nozawa CM. Effect of actinomycin D on simian rotavirus (SA11) replication in cell culture. Braz J Med Biol Res 2002; 35:445-9. [PMID: 11960193 DOI: 10.1590/s0100-879x2002000400006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Rotaviruses are the major cause of viral diarrhea in humans and animals. Actinomycin D (Act D) is an antibiotic that intercalates DNA and therefore inhibits DNA-dependent transcription. The current study was carried out to assess the influence of Act D on the replication of simian rotavirus (SA11) in cell culture. Virus-infected MA-104 cell cultures were studied in the presence of Act D at concentrations of 1.25 and 2.5 microg/ml. Treatment of rotavirus-infected cells with 2.5 microg/ml Act D 48 h post-infection reduced the cytoplasmic metachromasia after staining with acridine orange by 25%. Viral RNA labeled with 3H-uridine in the presence of the drug was separated by polyacrylamide gel electrophoresis. Viral RNA replication was not affected by Act D, but increased 3H-uridine uptake was demonstrable by infected cells in the presence of the drug. This possibly was due to the inhibition of cellular RNA synthesis by Act D, which thus enhances incorporation of the radionuclide into the viral RNA. Act D reduced the number of infected cells presenting virus-specific fluorescence 48 h post-infection by more than 50%. These data suggest that Act D may have complexed with viral RNA and prevented newly synthesized mRNA from being translated, but may not have prevented early replication.
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Affiliation(s)
- C C Stefanelli
- Laboratório de Virologia, Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, PR, Brasil
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45
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Berkhout B, Vastenhouw NL, Klasens BI, Huthoff H. Structural features in the HIV-1 repeat region facilitate strand transfer during reverse transcription. RNA (NEW YORK, N.Y.) 2001; 7:1097-1114. [PMID: 11497429 PMCID: PMC1370158 DOI: 10.1017/s1355838201002035] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Two obligatory DNA strand transfers take place during reverse transcription of a retroviral RNA genome. The first strand transfer is facilitated by terminal repeat (R) elements in the viral genome. This strand-transfer reaction depends on base pairing between the cDNA of the 5'R and the 3'R. There is accumulating evidence that retroviral R regions contain features other than sequence complementarity that stimulate this critical nucleic acid hybridization step. The R region of the human immunodeficiency virus type 1 (HIV-1) is relatively extended (97 nt) and encodes two well-conserved stem-loop structures, the TAR and poly(A) hairpins. The role of these motifs was studied in an in vitro strand-transfer assay with two separate templates, the 5'R donor and the 3'R acceptor, and mutants thereof. The results indicate that the upper part of the TAR hairpin structure in the 5'R donor is critical for efficient strand transfer. This seems to pose a paradox, as the 5'R template is degraded by RNase H before strand transfer occurs. We propose that it is not the RNA hairpin motif in the 5'R donor, but rather the antisense motif in the ssDNA copy, which can also fold a hairpin structure, that is critical for strand transfer. Mutation of the loop sequence in the TAR hairpin of the donor RNA, which is copied in the loop of the cDNA hairpin, reduces the transfer efficiency more than fivefold. It is proposed that the natural strand-transfer reaction is enhanced by interaction of the anti-TAR ssDNA hairpin with the TAR hairpin in the 3'R acceptor. Base pairing can occur between the complementary loops ("loop-loop kissing"), and strand transfer is completed by the subsequent formation of an extended RNA-cDNA duplex.
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Affiliation(s)
- B Berkhout
- Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, The Netherlands.
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Abstract
Actinomycin D is an anticancer antibiotic best know for inhibiting transcription by binding double-stranded DNA. Tight, sequence selective binding of actinomycin to single-stranded DNA is also known, however, and is implicated in biological activities including inhibition of (-) strand transfer by HIV reverse transcriptase. Oligonucleotide d(GTTAACCATAG) is one of the rare single-stranded DNAs that lack GC steps yet have high affinity for actinomycin. Oligonucleotide sequence and length requirements for drug binding were investigated by monitoring association of the fluorescent surrogate, 7-aminoactinomycin D, to d(GTTAACCATAG) and 31 related oligomers. The TAG-3' terminal sequence was essential for high-affinity binding, but was not sufficient. Five oligomers with TAG sequences on or near the 3'-end had high affinity [K(d) < or = 200 nM (oligomer)]. A sixth oligomer, d(GTAACCATATG), had moderately lower affinity (Kd = 370 nM), and other homologous oligomers had much lower affinity. The minimum length sequence for tight binding of 7-aminoactinomycin D was identified as only eight nucleotides, corresponding to d(AACCATAG). This octanucleotide is unstructured in the absence of actinomycin, and has the highest drug affinity of all oligomers examined (Kd = 125 nM). These studies show that high-affinity binding of 7-aminoactinomycin, and actinomycin D by extension, to single-stranded DNA does not require pre-existing secondary structure or any apparent propensity for secondary structure. It is proposed that actinomycin D binds to certain single-stranded DNA sequences by an induced-fit mechanism favored by participation of at least eight nucleotides, or the equivalent of four base pairs.
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Affiliation(s)
- H Yoo
- Department of Chemistry and Institute of Molecular Biophysics The Florida State University, Tallahassee, Florida, USA
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Berkhout B. Multiple biological roles associated with the repeat (R) region of the HIV-1 RNA genome. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2001; 48:29-73. [PMID: 10987088 DOI: 10.1016/s1054-3589(00)48003-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- B Berkhout
- Department of Human Retrovirology, University of Amsterdam, The Netherlands
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48
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Dorman N, Lever A. Comparison of viral genomic RNA sorting mechanisms in human immunodeficiency virus type 1 (HIV-1), HIV-2, and Moloney murine leukemia virus. J Virol 2000; 74:11413-7. [PMID: 11070043 PMCID: PMC113248 DOI: 10.1128/jvi.74.23.11413-11417.2000] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genomic RNA sorting between translation and packaging was examined for human immunodeficiency virus type 1 (HIV-1) and HIV-2 using actinomycin D and leptomycin B treatment. Both viruses behaved differently from a simple retrovirus under actinomycin D treatment. With leptomycin B, the lack of apparent functional separation between translation and packaging functions in lentiviruses was confirmed. HIV-2 RNA levels were more stable, but reverse transcriptase production declined similarly to HIV-1.
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Affiliation(s)
- N Dorman
- University of Cambridge Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, United Kingdom
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Guo J, Wu T, Anderson J, Kane BF, Johnson DG, Gorelick RJ, Henderson LE, Levin JG. Zinc finger structures in the human immunodeficiency virus type 1 nucleocapsid protein facilitate efficient minus- and plus-strand transfer. J Virol 2000; 74:8980-8. [PMID: 10982342 PMCID: PMC102094 DOI: 10.1128/jvi.74.19.8980-8988.2000] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleocapsid protein (NC) of human immunodeficiency virus type 1 (HIV-1) has two zinc fingers, each containing the invariant metal ion binding residues CCHC. Recent reports indicate that mutations in the CCHC motifs are deleterious for reverse transcription in vivo. To identify reverse transcriptase (RT) reactions affected by such changes, we have probed zinc finger functions in NC-dependent RT-catalyzed HIV-1 minus- and plus-strand transfer model systems. Our approach was to examine the activities of wild-type NC and a mutant in which all six cysteine residues were replaced by serine (SSHS NC); this mutation severely disrupts zinc coordination. We find that the zinc fingers contribute to the role of NC in complete tRNA primer removal from minus-strand DNA during plus-strand transfer. Annealing of the primer binding site sequences in plus-strand strong-stop DNA [(+) SSDNA] to its complement in minus-strand acceptor DNA is not dependent on NC zinc fingers. In contrast, the rate of annealing of the complementary R regions in (-) SSDNA and 3' viral RNA during minus-strand transfer is approximately eightfold lower when SSHS NC is used in place of wild-type NC. Moreover, unlike wild-type NC, SSHS NC has only a small stimulatory effect on minus-strand transfer and is essentially unable to block TAR-induced self-priming from (-) SSDNA. Our results strongly suggest that NC zinc finger structures are needed to unfold highly structured RNA and DNA strand transfer intermediates. Thus, it appears that in these cases, zinc finger interactions are important components of NC nucleic acid chaperone activity.
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Affiliation(s)
- J Guo
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA
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Götte M, Wainberg MA. Biochemical mechanisms involved in overcoming HIV resistance to nucleoside inhibitors of reverse transcriptase. Drug Resist Updat 2000; 3:30-38. [PMID: 11498363 DOI: 10.1054/drup.2000.0126] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The development of drug combinations that act effectively against both wild-type and mutated resistant forms of HIV-1 reverse transcriptase (RT) is a major goal in management of HIV disease. Recent studies have shown that resistance to different nucleoside analog RT inhibitors (NRTIs), an important class of anti-viral drugs, can result in different amino acid substitutions in close proximity to the dNTP binding pocket of the enzyme. Some of these mutations have been shown to cause cross- or multiple resistance among various members of this family of inhibitors. In contrast, certain combinations of amino acid substitutions can sometimes lead to increased drug susceptibility and may also result in resensitization of formerly resistant viruses. A biochemical understanding of these complex viral phenotypes may be of major importance in regard to development of novel chemotherapeutic strategies that can act at the level of drug-resistant mutated enzymes. In this review, we discuss several principles that help to explain the increased susceptibility and resensitization to some antiviral agents used in the context of combination treatment. The conclusions are largely based on our current understanding of mechanisms involved in drug-resistance to 3TC and AZT. Copyright 2000 Harcourt Publishers Ltd.
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Affiliation(s)
- Matthias Götte
- McGill University AIDS Centre, Lady Davis Institute - Jewish General Hospital, Montréal, Québec, CA
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