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Goettig P, Koch NG, Budisa N. Non-Canonical Amino Acids in Analyses of Protease Structure and Function. Int J Mol Sci 2023; 24:14035. [PMID: 37762340 PMCID: PMC10531186 DOI: 10.3390/ijms241814035] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/18/2023] [Accepted: 08/20/2023] [Indexed: 09/29/2023] Open
Abstract
All known organisms encode 20 canonical amino acids by base triplets in the genetic code. The cellular translational machinery produces proteins consisting mainly of these amino acids. Several hundred natural amino acids serve important functions in metabolism, as scaffold molecules, and in signal transduction. New side chains are generated mainly by post-translational modifications, while others have altered backbones, such as the β- or γ-amino acids, or they undergo stereochemical inversion, e.g., in the case of D-amino acids. In addition, the number of non-canonical amino acids has further increased by chemical syntheses. Since many of these non-canonical amino acids confer resistance to proteolytic degradation, they are potential protease inhibitors and tools for specificity profiling studies in substrate optimization and enzyme inhibition. Other applications include in vitro and in vivo studies of enzyme kinetics, molecular interactions and bioimaging, to name a few. Amino acids with bio-orthogonal labels are particularly attractive, enabling various cross-link and click reactions for structure-functional studies. Here, we cover the latest developments in protease research with non-canonical amino acids, which opens up a great potential, e.g., for novel prodrugs activated by proteases or for other pharmaceutical compounds, some of which have already reached the clinical trial stage.
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Affiliation(s)
- Peter Goettig
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Nikolaj G. Koch
- Biocatalysis Group, Technische Universität Berlin, 10623 Berlin, Germany;
- Bioanalytics Group, Institute of Biotechnology, Technische Universität Berlin, 10623 Berlin, Germany;
| | - Nediljko Budisa
- Bioanalytics Group, Institute of Biotechnology, Technische Universität Berlin, 10623 Berlin, Germany;
- Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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2
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Tariq M, Shoukat AB, Akbar S, Hameed S, Naqvi MZ, Azher A, Saad M, Rizwan M, Nadeem M, Javed A, Ali A, Aziz S. Epidemiology, risk factors, and pathogenesis associated with a superbug: A comprehensive literature review on hepatitis C virus infection. SAGE Open Med 2022; 10:20503121221105957. [PMID: 35795865 PMCID: PMC9252020 DOI: 10.1177/20503121221105957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 05/20/2022] [Indexed: 12/20/2022] Open
Abstract
Viral hepatitis is a major public health concern. It is associated with life threatening conditions including liver cirrhosis and hepatocellular carcinoma. Hepatitis C virus infects around 71 million people annually, resultantly 700,000 deaths worldwide. Extrahepatic associated chronic hepatitis C virus accounts for one fourth of total healthcare load. This review included a total of 150 studies that revealed almost 19 million people are infected with hepatitis C virus and 240,000 new cases are being reported each year. This trend is continually rising in developing countries like Pakistan where intravenous drug abuse, street barbers, unsafe blood transfusions, use of unsterilized surgical instruments and recycled syringes plays a major role in virus transmission. Almost 123–180 million people are found to be hepatitis C virus infected or carrier that accounts for 2%–3% of world’s population. The general symptoms of hepatitis C virus infection include fatigue, jaundice, dark urine, anorexia, fever malaise, nausea and constipation varying on severity and chronicity of infection. More than 90% of hepatitis C virus infected patients are treated with direct-acting antiviral agents that prevent progression of liver disease, decreasing the elevation of hepatocellular carcinoma. Standardizing the healthcare techniques, minimizing the street practices, and screening for viral hepatitis on mass levels for early diagnosis and prompt treatment may help in decreasing the burden on already fragmented healthcare system. However, more advanced studies on larger populations focusing on mode of transmission and treatment protocols are warranted to understand and minimize the overall infection and death stigma among masses.
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Affiliation(s)
- Mehlayl Tariq
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Abu Bakar Shoukat
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Sedrah Akbar
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Samaia Hameed
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Muniba Zainab Naqvi
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Ayesha Azher
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Muhammad Saad
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan.,BreathMAT Lab, IAD, Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan
| | - Muhammad Rizwan
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Muhammad Nadeem
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Anum Javed
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Asad Ali
- Institute of Microbiology and Molecular Genetics, University of the Punjab, Lahore, Punjab, Pakistan
| | - Shahid Aziz
- Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan.,BreathMAT Lab, IAD, Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad, Pakistan
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3
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Gauna A, Losada S, Lorenzo M, Toledo M, Bermúdez H, D'Angelo P, Sánchez D, Noya O. Use of Synthetic Peptides and Multiple Antigen Blot Assay in the Immunodiagnosis of Hepatitis C Virus Infection. Viral Immunol 2018; 31:568-574. [PMID: 30256730 DOI: 10.1089/vim.2018.0023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Acute hepatitis C virus (HCV) infection is usually asymptomatic, therefore, early diagnosis is rare. It may remain undiagnosed in individuals who progress to chronic infection, often until serious liver damage has developed. To incorporate the diagnosis of this viral disease in a multiple-diagnostic assay, we first analyzed by immunoinformatics the HCV subtype 1a polyprotein (specifically Core, E2, NS3, NS5A proteins) to select antigenic peptides to be tested initially by the Pepscan technique. Next, we performed the immunodiagnosis of HCV infection, using the Multiple Antigen Blot Assay (MABA). In 22 patients' sera included in this study, a 20-mer linear peptide belonging to the N-terminus of the worldwide conserved Core protein showed 100% sensitivity and specificity; other sequences showed different levels of antibody recognition. The use of MABA in combination with synthetic peptides as a source of multiple, specific, and nonexpensive antigens for other infectious diseases could represent a rapid, integrated, and inexpensive diagnostic methodology.
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Affiliation(s)
- Adriana Gauna
- 1 Programa de Doctorado en Biotecnología, Pontificia Universidad Católica de Valparaíso/Universidad Técnica Federico Santa María , Valparaíso, Chile
| | - Sandra Losada
- 2 Sección de Biohelmintiasis, Instituto de Medicina Tropical , Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela
| | - María Lorenzo
- 2 Sección de Biohelmintiasis, Instituto de Medicina Tropical , Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela
| | - Marilyan Toledo
- 3 Cátedra de Parasitología, Escuela de Medicina "Luis Razetti," Universidad Central de Venezuela , Caracas, Venezuela
| | - Henry Bermúdez
- 2 Sección de Biohelmintiasis, Instituto de Medicina Tropical , Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela
| | - Pierina D'Angelo
- 4 Laboratorio de Programas Especiales-Hepatitis y SIDA, Dpto de Virología, Gerencia Sectorial de Diagnóstico y Vigilancia Epidemiológica, Instituto Nacional de Higiene "Rafael Rangel ," Caracas, Venezuela
| | - Doneyla Sánchez
- 4 Laboratorio de Programas Especiales-Hepatitis y SIDA, Dpto de Virología, Gerencia Sectorial de Diagnóstico y Vigilancia Epidemiológica, Instituto Nacional de Higiene "Rafael Rangel ," Caracas, Venezuela
| | - Oscar Noya
- 2 Sección de Biohelmintiasis, Instituto de Medicina Tropical , Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela .,5 Centro para Estudios Sobre Malaria, Instituto de Altos Estudios "Dr. Arnoldo Gabaldón" Instituto Nacional de Higiene-Ministerio del Poder Popular para la Salud , Caracas, Venezuela
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4
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Vega S, Neira JL, Marcuello C, Lostao A, Abian O, Velazquez-Campoy A. NS3 protease from hepatitis C virus: biophysical studies on an intrinsically disordered protein domain. Int J Mol Sci 2013; 14:13282-306. [PMID: 23803659 PMCID: PMC3742187 DOI: 10.3390/ijms140713282] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/04/2013] [Accepted: 06/13/2013] [Indexed: 12/14/2022] Open
Abstract
The nonstructural protein 3 (NS3) from the hepatitis C virus (HCV) is responsible for processing the non-structural region of the viral precursor polyprotein in infected hepatic cells. NS3 protease activity, located at the N-terminal domain, is a zinc-dependent serine protease. A zinc ion, required for the hydrolytic activity, has been considered as a structural metal ion essential for the structural integrity of the protein. In addition, NS3 interacts with another cofactor, NS4A, an accessory viral protein that induces a conformational change enhancing the hydrolytic activity. Biophysical studies on the isolated protease domain, whose behavior is similar to that of the full-length protein (e.g., catalytic activity, allosteric mechanism and susceptibility to inhibitors), suggest that a considerable global conformational change in the protein is coupled to zinc binding. Zinc binding to NS3 protease can be considered as a folding event, an extreme case of induced-fit binding. Therefore, NS3 protease is an intrinsically (partially) disordered protein with a complex conformational landscape due to its inherent plasticity and to the interaction with its different effectors. Here we summarize the results from a detailed biophysical characterization of this enzyme and present new experimental data.
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Affiliation(s)
- Sonia Vega
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
| | - Jose L. Neira
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- Institute of Molecular and Cell Biology, Miguel Hernandez University, Elche (Alicante) 03202, Spain
| | - Carlos Marcuello
- Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragon (INA), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (C.M.); (A.L.)
| | - Anabel Lostao
- Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragon (INA), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (C.M.); (A.L.)
- ARAID Foundation, Government of Aragon, Zaragoza 50018, Spain
| | - Olga Abian
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- IIS Aragon–Aragon Health Science Institute (I+CS), Zaragoza 50009, Spain
- Network Biomedical Research Center on Hepatic and Digestive Diseases (CIBERehd), Barcelona 08036, Spain
- Authors to whom correspondence should be addressed; E-Mails: (O.A.); (A.V.-C.); Tel.: +34-976-761-000 (ext. 5417) (O.A.); +34-976-762-996 (A.V.-C.); Fax: +34-976-762-990 (O.A. & A.V.-C.)
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- ARAID Foundation, Government of Aragon, Zaragoza 50018, Spain
- Department of Biochemistry and Cellular and Molecular Biology, Faculty of Sciences, University of Zaragoza, Zaragoza 50009, Spain
- Authors to whom correspondence should be addressed; E-Mails: (O.A.); (A.V.-C.); Tel.: +34-976-761-000 (ext. 5417) (O.A.); +34-976-762-996 (A.V.-C.); Fax: +34-976-762-990 (O.A. & A.V.-C.)
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5
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Bittar C, Shrivastava S, Bhanja Chowdhury J, Rahal P, Ray RB. Hepatitis C virus NS2 protein inhibits DNA damage pathway by sequestering p53 to the cytoplasm. PLoS One 2013; 8:e62581. [PMID: 23638118 PMCID: PMC3640050 DOI: 10.1371/journal.pone.0062581] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 03/22/2013] [Indexed: 12/13/2022] Open
Abstract
Chronic hepatitis C virus (HCV) infection is an important cause of morbidity and mortality globally, and often leads to end-stage liver disease. The DNA damage checkpoint pathway induces cell cycle arrest for repairing DNA in response to DNA damage. HCV infection has been involved in this pathway. In this study, we assess the effects of HCV NS2 on DNA damage checkpoint pathway. We have observed that HCV NS2 induces ataxia-telangiectasia mutated checkpoint pathway by inducing Chk2, however, fails to activate the subsequent downstream pathway. Further study suggested that p53 is retained in the cytoplasm of HCV NS2 expressing cells, and p21 expression is not enhanced. We further observed that HCV NS2 expressing cells induce cyclin E expression and promote cell growth. Together these results suggested that HCV NS2 inhibits DNA damage response by altering the localization of p53, and may play a role in the pathogenesis of HCV infection.
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Affiliation(s)
- Cintia Bittar
- Department of Pathology, Saint Louis University, St. Louis, Missouri, United States of America
- Deaprtment of Biology, UNESP – São Paulo State University, São José do Rio Preto, São Paulo, Brazil
| | - Shubham Shrivastava
- Department of Pathology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Joydip Bhanja Chowdhury
- Department of Pathology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Paula Rahal
- Deaprtment of Biology, UNESP – São Paulo State University, São José do Rio Preto, São Paulo, Brazil
| | - Ratna B. Ray
- Department of Pathology, Saint Louis University, St. Louis, Missouri, United States of America
- * E-mail:
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6
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Varshney NK, Suresh Kumar R, Ignatova Z, Prabhune A, Pundle A, Dodson E, Suresh CG. Crystallization and X-ray structure analysis of a thermostable penicillin G acylase from Alcaligenes faecalis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:273-7. [PMID: 22442220 PMCID: PMC3310528 DOI: 10.1107/s1744309111053930] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 12/14/2011] [Indexed: 11/10/2022]
Abstract
The enzyme penicillin G acylase (EC 3.5.1.11) catalyzes amide-bond cleavage in benzylpenicillin (penicillin G) to yield 6-aminopenicillanic acid, an intermediate chemical used in the production of semisynthetic penicillins. A thermostable penicillin G acylase from Alcaligenes faecalis (AfPGA) has been crystallized using the hanging-drop vapour-diffusion method in two different space groups: C222(1), with unit-cell parameters a = 72.9, b = 86.0, c = 260.2 , and P4(1)2(1)2, with unit-cell parameters a = b = 85.6, c = 298.8 . Data were collected at 293 and the structure was determined using the molecular-replacement method. Like other penicillin acylases, AfPGA belongs to the N-terminal nucleophilic hydrolase superfamily, has undergone post-translational processing and has a serine as the N-terminal residue of the β-chain. A disulfide bridge has been identified in the structure that was not found in the other two known penicillin G cylase structures. The presence of the disulfide bridge is perceived to be one factor that confers higher stability to this enzyme.
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Affiliation(s)
| | - R. Suresh Kumar
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India
| | - Zoya Ignatova
- Department of Biochemistry, Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Asmita Prabhune
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India
| | - Archana Pundle
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India
| | - Eleanor Dodson
- York Structural Biology Laboratory, University of York, York YO10 5DD, England
| | - C. G. Suresh
- Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India
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7
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Abian O, Vega S, Neira JL, Velazquez-Campoy A. Conformational stability of hepatitis C virus NS3 protease. Biophys J 2011; 99:3811-20. [PMID: 21112306 DOI: 10.1016/j.bpj.2010.10.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 10/22/2010] [Accepted: 10/26/2010] [Indexed: 11/17/2022] Open
Abstract
The hepatitis C virus NS3 protease is responsible for the processing of the nonstructural region of viral precursor polyprotein in infected hepatic cells. NS3 has been considered a target for drug discovery for a long time. NS3 is a zinc-dependent serine protease. However, the zinc ion is not involved in the catalytic mechanism, because it is bound far away from the active site. Thus, zinc is essential for the structural integrity of the protein and it is considered to have a structural role. The first thermodynamic study on the conformational equilibrium and stability of NS3 and the effect of zinc on such equilibrium is presented here. In agreement with a previous calorimetric study on the binding of zinc to NS3, the global unfolding heat capacity is dominated by the zinc dissociation step, suggesting that the binding of zinc induces a significant structural rearrangement of the protein. In addition, contrary to other homologous zinc-dependent proteases, the zinc-free NS3 protease is not completely unstructured. It is apparent that the conformational landscape of hepatitis C virus NS3 protease is fairly complex due to its intrinsic plasticity, and to the interactions with its different effectors (zinc and the accessory viral protein NS4A) and their modulation of the population of the different conformational states.
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Affiliation(s)
- Olga Abian
- Institute of Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Zaragoza, Spain.
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8
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The Hepatitis C Virus Nonstructural Protein 2 (NS2): An Up-and-Coming Antiviral Drug Target. Viruses 2010; 2:1635-1646. [PMID: 21994698 PMCID: PMC3185728 DOI: 10.3390/v2081635] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/03/2010] [Accepted: 08/04/2010] [Indexed: 01/31/2023] Open
Abstract
Infection with Hepatitis C Virus (HCV) continues to be a major global health problem. To overcome the limitations of current therapies using interferon-α in combination with ribavirin, there is a need to develop drugs that specifically block viral proteins. Highly efficient protease and polymerase inhibitors are currently undergoing clinical testing and will become available in the next few years. However, with resistance mutations emerging quickly, additional enzymatic activities or functions of HCV have to be targeted by novel compounds. One candidate molecule is the nonstructural protein 2 (NS2), which contains a proteolytic activity that is essential for viral RNA replication. In addition, NS2 is crucial for the assembly of progeny virions and modulates various cellular processes that interfere with viral replication. This review describes the functions of NS2 in the life cycle of HCV and highlights potential antiviral strategies involving NS2.
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9
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Abian O, Neira JL, Velazquez-Campoy A. Thermodynamics of zinc binding to hepatitis C virus NS3 protease: a folding by binding event. Proteins 2010; 77:624-36. [PMID: 19536779 DOI: 10.1002/prot.22475] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The hepatitis C virus (HCV) nonstructural protein 3 (NS3) protease is responsible for the processing of the non-structural region of the viral precursor polyprotein in infected hepatic cells. HCV NS3 is a zinc-dependent serine protease. The zinc ion, which is bound far away from the active site and considered to have a structural role, is essential for the structural integrity of the protein; furthermore, the ion is required for the hydrolytic activity. Consequently, the NS3 zinc binding site has been considered for a long time as a possible target for drug discovery. As a first step towards this goal, the energetics of the NS3-zinc interaction and its effect on the NS3 conformation must be established and discussed. The thermodynamic characterization of zinc binding to NS3 protease by isothermal titration calorimetry and spectroscopy is presented here. Spectroscopic and calorimetric results suggest that a considerable conformational change in the protein is coupled to zinc binding. The energetics of the conformational change is comparable to that of the folding of a protein of similar size. Therefore, zinc binding to NS3 protease can be considered as a "folding by binding" event.
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Affiliation(s)
- Olga Abian
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, Zaragoza 50009, Spain
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10
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Yi M, Ma Y, Yates J, Lemon SM. Trans-complementation of an NS2 defect in a late step in hepatitis C virus (HCV) particle assembly and maturation. PLoS Pathog 2009; 5:e1000403. [PMID: 19412343 PMCID: PMC2669722 DOI: 10.1371/journal.ppat.1000403] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 03/31/2009] [Indexed: 12/12/2022] Open
Abstract
Recent studies using cell culture infection systems that recapitulate the entire life cycle of hepatitis C virus (HCV) indicate that several nonstructural viral proteins, including NS2, NS3, and NS5A, are involved in the process of viral assembly and release. Other recent work suggests that Ser-168 of NS2 is a target of CK2 kinase-mediated phosphorylation, and that this controls the stability of the genotype 1a NS2 protein. Here, we show that Ser-168 is a critical determinant in the production of infectious virus particles. Substitution of Ser-168 with Ala (or Gly) ablated production of infectious virus by cells transfected with a chimeric viral RNA (HJ3-5) containing core-NS2 sequences from the genotype 1a H77 virus within the background of genotype 2a JFH1 virus. An S168A substitution also impaired production of virus by cells transfected with JFH1 RNA. This mutation did not alter polyprotein processing or genome replication. This defect in virus production could be rescued by expression of wt NS2 in trans from an alphavirus replicon. The trans-complementing activities of NS2 from genotypes 1a and 2a demonstrated strong preferences for rescue of the homologous genotype. Importantly, the S168A mutation did not alter the association of core or NS5A proteins with host cell lipid droplets, nor prevent the assembly of core into particles with sedimentation and buoyant density properties similar to infectious virus, indicating that NS2 acts subsequent to the involvement of core, NS5A, and NS3 in particle assembly. Second-site mutations in NS2 as well as in NS5A can rescue the defect in virus production imposed by the S168G mutation. In aggregate, these results indicate that NS2 functions in trans, in a late-post assembly maturation step, perhaps in concert with NS5A, to confer infectivity to the HCV particle.
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Affiliation(s)
- MinKyung Yi
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX, USA.
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11
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Hepatitis C virus NS2 is a protease stimulated by cofactor domains in NS3. Proc Natl Acad Sci U S A 2009; 106:5342-7. [PMID: 19282477 DOI: 10.1073/pnas.0810950106] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chronic infection with hepatitis C virus (HCV) affects 130 million people worldwide and is a major cause of liver cirrhosis and liver cancer. After translation of the HCV RNA genome into a polyprotein, 2 viral proteases process its non-structural protein (NS) region. While the essential chymotrypsin-like serine protease NS3-4A mediates all cleavages downstream of NS3, the NS2-3 cysteine protease catalyzes a vital cleavage at the NS2/3 site. Protease activity of NS2-3 has been described to require, besides NS2, the N-terminal 181 aa of NS3. The latter domain corresponds to the NS3 serine protease domain and contains a structural Zn(2+)-binding site with functional importance for both viral proteases. The catalytic triad of the NS2-3 protease resides in NS2; the role of the NS3 part in proteolysis remained largely undefined. Here we report a basal proteolytic activity for NS2 followed by only 2 amino acids of NS3. Basal activity could be dramatically enhanced by the NS3 Zn(2+)-binding domain (NS3 amino acids 81-213) not only in cis but also in trans which, however, required a more extended N-terminal part of NS3 downstream of NS2 in cis. Thus, this study defines for the first time (i) NS2 as a bona fide protease, (ii) NS3 as its regulatory cofactor, and (iii) functional subdomains in NS3 that cooperate in NS2 protease activation. These findings give new mechanistic insights into function and regulation of the NS2 protease and have important implications for the development of anti-HCV therapeutics.
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12
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Progress on New Hepatitis C Virus Targets: NS2 and NS5A. NATO SCIENCE FOR PEACE AND SECURITY SERIES A: CHEMISTRY AND BIOLOGY 2009. [DOI: 10.1007/978-90-481-2339-1_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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13
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Sun Y, Guo HC. Structural constraints on autoprocessing of the human nucleoporin Nup98. Protein Sci 2008; 17:494-505. [PMID: 18287282 DOI: 10.1110/ps.073311808] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Nucleoporin Nup98, a 98-kDa protein component of the nuclear pore complex, plays an important role in both protein and RNA transport. During its maturation process, Nup98 undergoes post-translational autoproteolysis, which is critical for targeting to the NPC. Here we present high-resolution crystal structures of the C-terminal autoproteolytic domains of Nup98 (2.3 A for the wild type and 1.9 A for the S864A precursor), and propose a detailed autoproteolysis mechanism through an N-O acyl shift. Structural constraints are found at the autocleavage site, and could thus provide a driving force for autocleavage at the scissile peptide bond. Such structural constraints appear to be generated, at least in part, by anchoring a conserved phenylalanine side chain into a highly conserved hydrophobic pocket at the catalytic site. Our high-resolution crystal structures also reveal that three highly conserved residues, Tyr866, Gly867, and Leu868, provide most of the interactions between the autoproteolytic domain and the C-terminal tail. These results suggest that Nup98 may represent a new subtype of protein that utilizes autoprocessing to control biogenesis pathways and intracellular translocation.
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Affiliation(s)
- Yixin Sun
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118-2526, USA
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14
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Sheahan KL, Cordero CL, Satchell KJF. Autoprocessing of the Vibrio cholerae RTX toxin by the cysteine protease domain. EMBO J 2007; 26:2552-61. [PMID: 17464284 PMCID: PMC1868911 DOI: 10.1038/sj.emboj.7601700] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Accepted: 03/30/2007] [Indexed: 11/09/2022] Open
Abstract
Vibrio cholerae RTX is a large multifunctional bacterial toxin that causes actin crosslinking. Due to its size, it was predicted to undergo proteolytic cleavage during translocation into host cells to deliver activity domains to the cytosol. In this study, we identified a domain within the RTX toxin that is conserved in large clostridial glucosylating toxins TcdB, TcdA, TcnA, and TcsL; putative toxins from V. vulnificus, Yersinia sp., Photorhabdus sp., and Xenorhabdus sp.; and a filamentous/hemagglutinin-like protein FhaL from Bordetella sp. In vivo transfection studies and in vitro characterization of purified recombinant protein revealed that this domain from the V. cholerae RTX toxin is an autoprocessing cysteine protease whose activity is stimulated by the intracellular environment. A cysteine point mutation within the RTX holotoxin attenuated actin crosslinking activity suggesting that processing of the toxin is an important step in toxin translocation. Overall, we have uncovered a new mechanism by which large bacterial toxins and proteins deliver catalytic activities to the eukaryotic cell cytosol by autoprocessing after translocation.
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Affiliation(s)
- Kerri-Lynn Sheahan
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Christina L Cordero
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Karla J Fullner Satchell
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Department of Microbiology-Immunology, Northwestern University, 303 E. Chicago Avenue, Tarry 3-713, Chicago, IL 60611, USA. Tel.: +1 312 503 2162; Fax: +1 312 503 1339; E-mail:
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15
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Tedbury PR, Harris M. Characterisation of the role of zinc in the hepatitis C virus NS2/3 auto-cleavage and NS3 protease activities. J Mol Biol 2006; 366:1652-60. [PMID: 17239391 DOI: 10.1016/j.jmb.2006.12.062] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 12/14/2006] [Accepted: 12/19/2006] [Indexed: 11/20/2022]
Abstract
Cleavage of the hepatitis C virus polyprotein between the non-structural NS2 and NS3 proteins is mediated by a poorly characterised auto-proteolytic activity that maps to the C terminus of NS2 and the N terminus of NS3, but is distinct from the NS3 protease activity responsible for downstream cleavages in the polyprotein. We have exploited the fact that the minimal precursor (residues 904-1206 of the HCV polyprotein) can be expressed as an insoluble protein in Escherichia coli and subsequently refolded into a form active for both auto-cleavage and NS3 protease activity, to further characterise the NS2/3 auto-cleavage activity. We show that both activities are zinc-dependent and show an absolute requirement for cysteine residues 1123, 1125 and 1171 within NS3. In contrast cysteine 922 (within NS2) is only required for NS2/3 auto-cleavage activity and histidine 1175 is only required for NS3 activity. Although the complete NS3 protease domain (including the C-terminal alpha-helix) is required for NS2/3 auto-cleavage, the activity of the NS3 protease is not essential. Lastly we show that the NS2/3 auto-cleavage activity is more sensitive to zinc chelation by 1,10-phenanthroline than the NS3 protease activity. This observation is consistent with different conformations of the precursor competent for either NS2/3 auto-cleavage or NS3 protease activity; these two conformations can be distinguished by their relative strength and geometry of zinc coordination.
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Affiliation(s)
- Philip R Tedbury
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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16
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Lorenz IC, Marcotrigiano J, Dentzer TG, Rice CM. Structure of the catalytic domain of the hepatitis C virus NS2-3 protease. Nature 2006; 442:831-5. [PMID: 16862121 DOI: 10.1038/nature04975] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Accepted: 06/09/2006] [Indexed: 01/21/2023]
Abstract
Hepatitis C virus is a major global health problem affecting an estimated 170 million people worldwide. Chronic infection is common and can lead to cirrhosis and liver cancer. There is no vaccine available and current therapies have met with limited success. The viral RNA genome encodes a polyprotein that includes two proteases essential for virus replication. The NS2-3 protease mediates a single cleavage at the NS2/NS3 junction, whereas the NS3-4A protease cleaves at four downstream sites in the polyprotein. NS3-4A is characterized as a serine protease with a chymotrypsin-like fold, but the enzymatic mechanism of the NS2-3 protease remains unresolved. Here we report the crystal structure of the catalytic domain of the NS2-3 protease at 2.3 A resolution. The structure reveals a dimeric cysteine protease with two composite active sites. For each active site, the catalytic histidine and glutamate residues are contributed by one monomer, and the nucleophilic cysteine by the other. The carboxy-terminal residues remain coordinated in the two active sites, predicting an inactive post-cleavage form. Proteolysis through formation of a composite active site occurs in the context of the viral polyprotein expressed in mammalian cells. These features offer unexpected insights into polyprotein processing by hepatitis C virus and new opportunities for antiviral drug design.
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Affiliation(s)
- Ivo C Lorenz
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, 1230 York Avenue, New York, New York 10021, USA
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17
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Zhang C, Cai Z, Kim YC, Kumar R, Yuan F, Shi PY, Kao C, Luo G. Stimulation of hepatitis C virus (HCV) nonstructural protein 3 (NS3) helicase activity by the NS3 protease domain and by HCV RNA-dependent RNA polymerase. J Virol 2005; 79:8687-97. [PMID: 15994762 PMCID: PMC1168731 DOI: 10.1128/jvi.79.14.8687-8697.2005] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Accepted: 03/22/2005] [Indexed: 01/28/2023] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 3 (NS3) possesses multiple enzyme activities. The N-terminal one-third of NS3 primarily functions as a serine protease, while the remaining two-thirds of NS3 serve as a helicase and nucleoside triphosphatase. Whether the multiple enzyme activities of NS3 are functionally interdependent and/or modulated by other viral NS proteins remains unclear. We performed biochemical studies to examine the functional interdependence of the NS3 protease and helicase domains and the modulation of NS3 helicase by NS5B, an RNA-dependent RNA polymerase (RdRp). We found that the NS3 protease domain of the full-length NS3 (NS3FL) enhances the NS3 helicase activity. Additionally, HCV RdRp stimulates the NS3FL helicase activity by more than sevenfold. However, the helicase activity of the NS3 helicase domain was unaffected by HCV RdRp. Glutathione S-transferase pull-down as well as fluorescence anisotropy results revealed that the NS3 protease domain is required for specific NS3 and NS5B interaction. These findings suggest that HCV RdRp regulates the functions of NS3 during HCV replication. In contrast, NS3FL does not increase NS5B RdRp activity in vitro, which is contrary to a previously published report that the HCV NS3 enhances NS5B RdRp activity.
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Affiliation(s)
- Chen Zhang
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536, USA
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18
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Abstract
Hepatitis C virus (HCV) has infected millions of people worldwide and has emerged as a global health crisis. The currently available therapy is interferon (IFN) either alone or in combination with ribavirin. However, the disappointing efficacy of IFN has led to the considerable need for improved treatments and a number of new therapies are under evaluation in clinical trials. These include pegylated IFNs, which have altered physiochemical characteristics allowing once-weekly dosing. Combination of pegylated IFN with ribavirin should further improve sustained response rates. However, not all patients are successfully treated with IFNs, particularly those infected with genotype 1 of the virus, and it is likely that potent, specific drugs will be required. The majority of new approaches currently trying to combat this viral disease are aimed at inhibition of viral targets. Most effort has been directed towards inhibition of the NS3 serine protease, and potent inhibitors have now been described. However, a clinical candidate is yet to emerge against this difficult target. Considerable work by leading researchers has provided crystal structures of the key replicative enzymes, NS3 protease, NS3 helicase, NS5B polymerase and full-length NS3 protease-helicase, and there is much hope that such structural information will bear fruit. More recently, inhibition of host targets, particularly inosine monophosphate dehydrogenase (IMPDH), has become of interest and there are on-going clinical trials with such inhibitors. Research aimed at novel treatments for HCV disease is gathering pace and very recent developments in cell-based assay systems can only hasten the discovery of improved therapies.
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Affiliation(s)
- B W Dymock
- Roche Discovery Welwyn, Broadwater Road, Welwyn Garden City, Herts, AL7 3AY, UK.
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19
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Bartenschlager R, Frese M, Pietschmann T. Novel insights into hepatitis C virus replication and persistence. Adv Virus Res 2005; 63:71-180. [PMID: 15530561 DOI: 10.1016/s0065-3527(04)63002-8] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hepatitis C virus (HCV) is a small enveloped RNA virus that belongs to the family Flaviviridae. A hallmark of HCV is its high propensity to establish a persistent infection that in many cases leads to chronic liver disease. Molecular studies of the virus became possible with the first successful cloning of its genome in 1989. Since then, the genomic organization has been delineated, and viral proteins have been studied in some detail. In 1999, an efficient cell culture system became available that recapitulates the intracellular part of the HCV life cycle, thereby allowing detailed molecular studies of various aspects of viral RNA replication and persistence. This chapter attempts to summarize the current state of knowledge in these most actively worked on fields of HCV research.
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Affiliation(s)
- Ralf Bartenschlager
- Department of Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
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20
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Chen J, Huang Y, Wu H, Ni X, Cheng H, Fan J, Gu S, Gu X, Cao G, Ying K, Mao Y, Lu Y, Xie Y. Molecular cloning and characterization of a novel human J-domain protein gene (HDJ3) from the fetal brain. J Hum Genet 2003; 48:217-221. [PMID: 12768437 DOI: 10.1007/s10038-003-0012-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2002] [Accepted: 02/17/2003] [Indexed: 11/26/2022]
Abstract
The J-domain is believed to be part of a chaperone involved in protein folding. From a fetal brain cDNA library, we isolated a cDNA of 3249 bp encoding a novel human J-domain protein, which was named as HDJ3. The expression pattern of HDJ3 was examined by reverse transcription/polymerase chain reaction, which suggested that the transcripts were highly expressed in human pancreas and selectively expressed in human brain, lung, liver, skeletal muscle and kidney. The results also showed that a probable splice variant of HDJ3 gene might exist. The HDJ3 gene was located on human chromosome 12q13.1-12q13.2 and consisted of seven exons spanning 8593 bp of the human genome. PSORT analysis indicated that the HDJ3 gene contained a transmembrane domain. The putative protein of the HDJ3 gene was highly homologous to rat dopamine-receptor-interacting protein, suggesting that it was a novel member of the molecular chaperone family and functionally related to dopamine signal transduction.
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Affiliation(s)
- Juxiang Chen
- Department of Neurosurgery, Chang Zheng Hospital, Second Military Medical University, 200003, Shanghai, People's Republic of China
| | - Yan Huang
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
- United Gene Holdings, 200092, Shanghai, P.R. China
| | - Hai Wu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Xiaohua Ni
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Haipeng Cheng
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Jingping Fan
- Department of Neurosurgery, Chang Zheng Hospital, Second Military Medical University, 200003, Shanghai, People's Republic of China
| | - Shaohua Gu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Xing Gu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Gentao Cao
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Kang Ying
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Yumin Mao
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China
| | - Yicheng Lu
- Department of Neurosurgery, Chang Zheng Hospital, Second Military Medical University, 200003, Shanghai, People's Republic of China
| | - Yi Xie
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 200433, Shanghai , P.R. China.
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21
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Abstract
A myriad of new therapies for treating hepatitis C are in various stages of preclinical and clinical development. As reviewed here, these include nucleic acid-based approaches (antisense and ribozymes), small molecule inhibitors of essential hepatitis C virus (HCV)-encoded enzymes (protease, helicase, and polymerase), immune modulation, and immunotherapy. As more details of the HCV lifecycle are elucidated, new targets and approaches will be discovered. Drug development is difficult, expensive, and always agonizingly slow for patients in need and their physicians. Nonetheless, a broad effort has been mounted for HCV, and substantial progress has been achieved. The prospects for new HCV treatments are bright.
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Affiliation(s)
- Raffaele De Francesco
- Istituto di Ricerche di Biologia Molecolare P. Angeletti, Via Pontina KM 30,600, 00040 Pomezia, Rome, Italy.
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22
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Abstract
The Hepatitis C virus is a positive-stranded RNA virus which is the causal agent for a chronic liver infection afflicting more than 170,000,000 people world-wide. The HCV genome is approximately 9.6 kb in length and the proteome encoded is a polyprotein of a little more than 3000 amino acid residues. This polyprotein is processed by a combination of host and viral proteases into structural and non-structural proteins. The functions of most of these proteins have been established by analogy to other viruses and by sequence homology to known proteins, as well as subsequent biochemical analysis. Two of the non-structural proteins, NS4b and NS5a, are still of unknown function. The development of antivirals for this infectious agent has been hampered by the lack of robust and economical cell culture and animal infection systems. Recent progress in the molecular virology of HCV has come about due to the definition of molecular clones, which are infectious in the chimpanzee, the development of a subgenomic replicon system in Huh7 cells, and the description of a transgenic mouse model for HCV infection. Recent progress in the structural biology of the virus has led to the determination of high resolution three-dimensional structures of a number of the key virally encoded enzymes, including the NS3 protease, NS3 helicase, and NS5b RNA-dependent RNA polymerase. In some cases these structures have been determined in complex with substrates, co-factors (NS4a), and inhibitors. Finally, a variety of techniques have been used to define host factors, which may be required for HCV replication, although this work is just beginning.
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Affiliation(s)
- S Rosenberg
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
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23
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Pallaoro M, Lahm A, Biasiol G, Brunetti M, Nardella C, Orsatti L, Bonelli F, Orrù S, Narjes F, Steinkühler C. Characterization of the hepatitis C virus NS2/3 processing reaction by using a purified precursor protein. J Virol 2001; 75:9939-46. [PMID: 11559826 PMCID: PMC114565 DOI: 10.1128/jvi.75.20.9939-9946.2001] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2001] [Accepted: 07/23/2001] [Indexed: 01/12/2023] Open
Abstract
The NS2-NS3 region of the hepatitis C virus polyprotein encodes a proteolytic activity that is required for processing of the NS2/3 junction. Membrane association of NS2 and the autocatalytic nature of the NS2/3 processing event have so far constituted hurdles to the detailed investigation of this reaction. We now report the first biochemical characterization of the self-processing activity of a purified NS2/3 precursor. Using multiple sequence alignments, we were able to define a minimal domain, devoid of membrane-anchoring sequences, which was still capable of performing the processing reaction. This truncated protein was efficiently expressed and processed in Escherichia coli. The processing reaction could be significantly suppressed by growth in minimal medium in the absence of added zinc ions, leading to the accumulation of an unprocessed precursor protein in inclusion bodies. This protein was purified to homogeneity, refolded, and shown to undergo processing at the authentic NS2/NS3 cleavage site with rates comparable to those observed using an in vitro-translated full-length NS2/3 precursor. Size-exclusion chromatography and a dependence of the processing rate on the concentration of truncated NS2/3 suggested a functional multimerization of the precursor protein. However, we were unable to observe trans cleavage activity between cleavage-site mutants and active-site mutants. Furthermore, the cleavage reaction of the wild-type protein was not inhibited by addition of a mutant that was unable to undergo self-processing. Site-directed mutagenesis data and the independence of the processing rate from the nature of the added metal ion argue in favor of NS2/3 being a cysteine protease having Cys993 and His952 as a catalytic dyad. We conclude that a purified protein can efficiently reproduce processing at the NS2/3 site in the absence of additional cofactors.
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Affiliation(s)
- M Pallaoro
- Department of Biochemistry, Istituto di Ricerche di Biologia Molecolare "P. Angeletti," Pomezia, Italy
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24
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Gesell JJ, Liu D, Madison VS, Hesson T, Wang YS, Weber PC, Wyss DF. Design, high-level expression, purification and characterization of soluble fragments of the hepatitis C virus NS3 RNA helicase suitable for NMR-based drug discovery methods and mechanistic studies. PROTEIN ENGINEERING 2001; 14:573-82. [PMID: 11579226 DOI: 10.1093/protein/14.8.573] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
RNA helicases represent a family of enzymes that unwind double-stranded (ds) RNA in a nucleoside triphosphate (NTP)-dependent fashion and which are required in all aspects of cellular RNA metabolism and processing. The hepatitis C virus (HCV) non-structural 3 (NS3) protein possesses a serine protease activity in the N-terminal one-third, whereas RNA-stimulated NTPase and helicase activities reside in the C-terminal portion of the 631 amino acid residue bifunctional enzyme. The HCV NS3 RNA helicase is of key importance in the life cycle of HCV, which makes it a target for the development of therapeutics. However, neither the precise mechanism nor the substrate structure has been defined for this enzyme. For nuclear magnetic resonance (NMR)-based drug discovery methods and for mechanistic studies we engineered, prepared and characterized various truncated constructs of the 451-residue HCV NS3 RNA helicase. Our goal was to produce smaller fragments of the enzyme, which would be amenable to solution NMR techniques while retaining their native NTP and/or nucleic acid binding sites. Solution conditions were optimized to obtain high-quality heteronuclear NMR spectra of nitrogen-15 isotope-labeled constructs, which are typical of well-folded monomeric proteins. Moreover, NMR binding studies and functional data directly support the correct folding of these fragments.
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Affiliation(s)
- J J Gesell
- These two authors contributed equally to this work. Department of Structural Chemistry, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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25
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Metzler DE, Metzler CM, Sauke DJ. Transferring Groups by Displacement Reactions. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50015-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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26
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Affiliation(s)
- R Bartenschlager
- Institute for Virology, Johannes-Gutenberg University Mainz, Obere Zahlbacher Strabetae 67, 55131 Mainz, Germany.
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27
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Lohmann V, Roos A, Körner F, Koch JO, Bartenschlager R. Biochemical and structural analysis of the NS5B RNA-dependent RNA polymerase of the hepatitis C virus. J Viral Hepat 2000; 7:167-74. [PMID: 10849258 DOI: 10.1046/j.1365-2893.2000.00218.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Hepatitis C virus (HCV), the major causative agent of chronic and sporadic non-A, non-B hepatitis worldwide, is a distinct member of the Flaviviridae virus family. These viruses have in common a plus-strand RNA genome that is replicated in the cytoplasm of the infected cell via minus-strand RNA intermediates. Owing to the lack of reliable cell culture systems and convenient animal models for HCV, the mechanisms governing RNA replication are not known. As a first step towards the development of appropriate in vitro systems, we expressed the NS5B RNA-dependent RNA polymerase (RdRp) in insect cells, purified the protein to near homogeneity and studied its biochemical properties. It is a primer- and RNA template-dependent RNA polymerase able to copy long heteropolymeric templates without additional viral or cellular cofactors. We determined the optimal reaction parameters, the kinetic constants and the substrate specificity of the enzyme, which turned out to be similar to those described for the 3D polymerase of poliovirus. By analysing a series of nucleosidic and non-nucleosidic compounds for their effect on RdRp activity, we found that ribavirin triphosphates have no inhibitory effect, providing direct experimental proof that the therapeutic effect observed in patients is not related to a direct inhibition of the viral polymerase. Finally, mutation analysis was performed to map the minimal NS5B sequence required for enzymatic activity and to identify the 'classical' polymerase motifs important for template and NTP binding and catalysis.
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Affiliation(s)
- V Lohmann
- Institute for Virology, Johannes-Gutenberg University Mainz, Mainz, Germany
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28
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29
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Darke PL, Jacobs AR, Waxman L, Kuo LC. Inhibition of hepatitis C virus NS2/3 processing by NS4A peptides. Implications for control of viral processing. J Biol Chem 1999; 274:34511-4. [PMID: 10574908 DOI: 10.1074/jbc.274.49.34511] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NS2/3 protease of hepatitis C virus is responsible for a single cleavage in the viral polyprotein between the nonstructural proteins NS2 and NS3. The minimal protein region necessary to catalyze this cleavage includes most of NS2 and the N-terminal one-third of NS3. Autocleavage reactions using NS2/3 protein translated in vitro are used here to investigate the inhibitory potential of peptides likely to affect the reaction. Peptides representing the cleaved sequence have no effect upon reaction rates, and the reaction rate is insensitive to dilution. Both results are consistent with prior suggestions that the NS2/3 cleavage is an intramolecular reaction. Surprisingly, peptides containing the 12-amino acid region of NS4A responsible for binding to NS3 inhibit the NS2/3 reaction with K(i) values as low as 3 microM. Unrelated peptide sequences of similar composition are not inhibitory, and neither are peptides containing incomplete segments of the NS4A region that binds to NS3. Inhibition of NS2/3 by NS4A peptides can be rationalized from the organizing effect of NS4A on the N terminus of NS3 (the NS2/3 cleavage point) as suggested by the known three-dimensional structure of the NS3 protease domain (Yan, Y., Li, Y., Munshi, S., Sardana, V., Cole, J. L., Sardana, M., Steinkuhler, C., Tomei, L., De Francesco, R., Kuo, L. C., and Chen, Z. (1998) Protein Sci. 7, 837-847). These findings may imply a sequential order to proteolytic maturation events in hepatitis C virus.
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Affiliation(s)
- P L Darke
- Department of Antiviral Research, Merck Research Laboratories, West Point, Pennsylvania 19486, USA
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30
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Yao N, Reichert P, Taremi SS, Prosise WW, Weber PC. Molecular views of viral polyprotein processing revealed by the crystal structure of the hepatitis C virus bifunctional protease-helicase. Structure 1999; 7:1353-63. [PMID: 10574797 DOI: 10.1016/s0969-2126(00)80025-8] [Citation(s) in RCA: 319] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Hepatitis C virus (HCV) currently infects approximately 3% of the world's population. HCV RNA is translated into a polyprotein that during maturation is cleaved into functional components. One component, nonstructural protein 3 (NS3), is a 631-residue bifunctional enzyme with protease and helicase activities. The NS3 serine protease processes the HCV polyprotein by both cis and trans mechanisms. The structural aspects of cis processing, the autoproteolysis step whereby the protease releases itself from the polyprotein, have not been characterized. The structural basis for inclusion of protease and helicase activities in a single polypeptide is also unknown. RESULTS We report here the 2.5 A resolution structure of an engineered molecule containing the complete NS3 sequence and the protease activation domain of nonstructural protein 4A (NS4A) in a single polypeptide chain (single chain or scNS3-NS4A). In the molecule, the helicase and protease domains are segregated and connected by a single strand. The helicase necleoside triphosphate and RNA interaction sites are exposed to solvent. The protease active site of scNS3-NS4A is occupied by the NS3 C terminus, which is part of the helicase domain. Thus, the intramolecular complex shows one product of NS3-mediated cleavage at the NS3-NS4A junction of the HCV polyprotein bound at the protease active site. CONCLUSIONS The scNS3-NS4A structure provides the first atomic view of polyprotein cis processing. Both local and global structural rearrangements follow the cis cleavage reaction, and large segments of the polyprotein can be folded prior to proteolytic processing. That the product complex of the cis cleavage reaction exists in a stable molecular conformation suggests autoinhibition and substrate-induced activation mechanisms for regulation of NS3 protease activity.
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Affiliation(s)
- N Yao
- Structural Chemistry Department, Schering-Plough Research Institute, Kenilworth, NJ 07033-0539, USA
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31
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Moser C, Stettler P, Tratschin JD, Hofmann MA. Cytopathogenic and noncytopathogenic RNA replicons of classical swine fever virus. J Virol 1999; 73:7787-94. [PMID: 10438869 PMCID: PMC104306 DOI: 10.1128/jvi.73.9.7787-7794.1999] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
To determine the minimal requirements for autonomous RNA replication of classical swine fever virus (CSFV), genomes having in-frame deletions within the genes for structural and flanking nonstructural proteins were constructed, based on an infectious cDNA clone of CSFV Alfort/187. RNA was transcribed in vitro from the respective plasmids and transfected into SK-6 swine kidney cells. The replication competence of the RNA was determined by immunostaining transfected cells for CSFV NS3 protein and by analysis of cell extracts for viral RNA, as well as protein synthesis at different times after transfection. The genes encoding N(pro), C, E(rns), E1, E2, p7, and NS2 proved to be dispensable for RNA replication, but the efficiency of replication varied strongly between individual constructs. RNA replicons containing the complete NS2-NS3 gene persisted in transfected cells and continued to replicate without causing any obvious morphological or functional damage to the cells, whereas genomes lacking the NS2 gene replicated more efficiently and induced a cytopathic effect. These findings suggest that NS2, although it is not essential for pestivirus RNA replication, has a regulatory function therein. Both cytopathogenic and noncytopathogenic replicons were packaged into virus particles provided in trans by a cotransfected full-length helper virus genome.
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Affiliation(s)
- C Moser
- Institute of Virology and Immunoprophylaxis, CH-3147 Mittelhäusern, Switzerland
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Kasche V, Lummer K, Nurk A, Piotraschke E, Rieks A, Stoeva S, Voelter W. Intramolecular autoproteolysis initiates the maturation of penicillin amidase from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1433:76-86. [PMID: 10446361 DOI: 10.1016/s0167-4838(99)00155-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The penicillin amidase (PA) from Escherichia coli belongs to a group of proteolytically processed bacterial enzymes. The mechanism of the maturation of the single polypeptide proenzyme has been studied for the PA from E. coli using a slowly processing mutant proenzyme. The mutant proenzyme was constructed by replacing Thr with Gly in the Thr(263)-Ser(264) bond that must be hydrolysed in active PA. The mutant proenzyme was purified by biospecific affinity chromatography using an immobilized monoclonal antibody against PA. The maturation of the free and covalently immobilized purified proenzyme was studied in vitro. For the free proenzyme the same products with PA activity as observed in homogenates of wild-type PA-producing E. coli cells were found to be formed during this process. A kinetic analysis of the possible inter- and intramolecular processes involved in the maturation demonstrated that unambiguous evidence for the existence of intramolecular processes can only be obtained in systems where intermolecular processes are excluded. The Gly(263)-Ser(264) bond was found to be hydrolysed first in the free and immobilized mutant proenzyme, based on determinations of mass spectra, N-terminal sequences and active site concentrations. In the system with immobilized proenzyme intermolecular processes are excluded, demonstrating that this bond is hydrolysed by intramolecular autoproteolysis. Based on the known three-dimensional structure of the PA from E. coli the same maturation mechanism should apply for the wild-type proenzyme.
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Affiliation(s)
- V Kasche
- AB Biotechnologie II, TU-Hamburg-Harburg, Denickestrasse 15, D-21071, Hamburg, Germany.
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Abstract
The NS3 serine proteinase is regarded as one of the preferred targets for the development of therapeutic agents against hepatitis C virus (HCV). Possible mechanisms of NS3 inhibitors include: (i) interference with the activation of the enzyme by its NS4A cofactor; (ii) binding to the structural zinc site; and (iii) binding to the active site. These mechanisms have been explored in detail by structural analysis of the enzyme. (i) The NS4A cofactor binds to the amino-terminal beta-barrel domain of the NS3 proteinase bringing about several conformational changes that result in enzyme activation. The interaction between NS3 and NS4A involves a very large surface area and therefore it is not a likely target for the development of inhibitors. (ii) The NS3 proteinase contains a structural zinc binding site. Spectroscopic studies have shown that changes in the conformation of this metal-binding site correlate with changes in the specific activity of the enzyme, and the NS3 proteinase is inhibited by compounds capable of extracting zinc from its native coordination sphere. (iii) Based on the observation that the NS3 proteinase undergoes inhibition by its cleavage products, potent, active site-directed inhibitors have been generated. Kinetic studies, site-directed mutagenesis, and molecular modelling have been used to characterize the interactions between the NS3 proteinase and its product inhibitors.
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Affiliation(s)
- R De Francesco
- Istituto di Ricerche di Biologia Molecolare P. Angeletti (IRBM), Pomezia, Italy
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Bartenschlager R. The NS3/4A proteinase of the hepatitis C virus: unravelling structure and function of an unusual enzyme and a prime target for antiviral therapy. J Viral Hepat 1999; 6:165-81. [PMID: 10607229 DOI: 10.1046/j.1365-2893.1999.00152.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The hepatitis C virus (HCV) is a major causative agent of transfusion-acquired and sporadic non-A, non-B hepatitis worldwide. Infections most often persist and lead, in approximately 50% of all patients, to chronic liver disease. As is characteristic for a member of the family Flaviviridae, HCV has a plus-strand RNA genome encoding a polyprotein, which is cleaved co- and post-translationally into at least 10 different products. These cleavages are mediated, among others, by a virally encoded chymotrypsin-like serine proteinase located in the N-terminal domain of non-structural protein 3 (NS3). Activity of this enzyme requires NS4A, a 54-residue polyprotein cleavage product, to form a stable complex with the NS3 domain. This review will describe the biochemical properties of the NS3/4A proteinase, its X-ray crystal structure and current attempts towards development of efficient inhibitors.
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Affiliation(s)
- R Bartenschlager
- Institute for Virology, Johannes-Gutenberg University Mainz, Mainz, Germany
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Abstract
Despite an urgent medical need, a broadly effective anti-viral therapy for the treatment of infections with hepatitis C viruses (HCVs) has yet to be developed. One of the approaches to anti-HCV drug discovery is the design and development of specific small molecule drugs to inhibit the proteolytic processing of the HCV polyprotein. This proteolytic processing is catalyzed by a chymotrypsin-like serine protease which is located in the N-terminal region of non-structural protein 3 (NS3). This protease domain forms a tight, non-covalent complex with NS4A, a 54 amino acid activator of NS3 protease. The C-terminal two-thirds of the NS3 protein contain a helicase and a nucleic acid-stimulated nucleoside triphosphatase (NTPase) activities which are probably involved in viral replication. This review will focus on the structure and function of the serine protease activity of NS3/4A and the development of inhibitors of this activity.
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Affiliation(s)
- A D Kwong
- Vertex Pharmaceuticals, Inc., Cambridge, MA 02139, USA.
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