title: Structural characterization of the HSP70 interaction domain of the hepatitis C viral protein NS5A.
abstract: We previously identified the NS5A/HSP70 binding site to be a hairpin moiety at C-terminus of NS5A domain I and showed a corresponding cyclized polyarginine-tagged synthetic peptide (HCV4) significantly blocks virus production. Here, sequence comparison confirmed five residues to be conserved. Based on NS5A domain I crystal structure, Phe171, Val173, and Tyr178 were predicted to form the binding interface. Substitution of Phe171 and Val173 with more hydrophobic unusual amino acids improved peptide antiviral activity and HSP70 binding, while similar substitutions at Tyr178 had a negative effect. Substitution of non-conserved residues with arginines maintained antiviral activity and HSP70 binding and dispensed with polyarginine tag for cellular entry. Peptide cyclization improved antiviral activity and HSP70 binding. The cyclic retro-inverso analog displayed the best antiviral properties. FTIR spectroscopy confirmed a secondary structure consisting of an N-terminal beta-sheet followed by a turn and a C-terminal beta-sheet. These peptides constitute a new class of anti-HCV compounds.
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.
authors.forename: Ronik
authors.initials: R
authors.lastname: Khachatoorian
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.
authors.forename: Piotr
authors.initials: P
authors.lastname: Ruchala
authors.affiliation: Division of Molecular Medicine at the Department of Medicine, Los Angeles County Harbor-UCLA Medical Center, Torrance, California, United States of America.
authors.forename: Alan
authors.initials: A
authors.lastname: Waring
authors.affiliation: Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Chun-Ling
authors.initials: CL
authors.lastname: Jung
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.
authors.forename: Ekambaram
authors.initials: E
authors.lastname: Ganapathy
authors.affiliation: Molecular Biology Interdepartmental Ph.D. Program (MBIDP), Molecular Biology Institute, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.|Molecular Biology Institute, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.
authors.forename: Nicole
authors.initials: N
authors.lastname: Wheatley
authors.affiliation: Department of Human Genetics, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.
authors.forename: Christopher
authors.initials: C
authors.lastname: Sundberg
authors.affiliation: Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.|Department of Surgery, The Board of Governors Regenerative Medicine Institute at Cedars-Sinai Medical center, Los Angeles, California, United States of America.
authors.forename: Vaithilingaraja
authors.initials: V
authors.lastname: Arumugaswami
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.|Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.|UCLA AIDS Institute, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.
authors.forename: Asim
authors.initials: A
authors.lastname: Dasgupta
authors.affiliation: Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.|Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.|UCLA AIDS Institute, David Geffen School of Medicine at University of California, Los Angeles, California, United States of America.
authors.forename: Samuel W
authors.initials: SW
authors.lastname: French
mesh_terms: D019943:Amino Acid Substitution; D001665:Binding Sites; D002460:Cell Line; D017124:Conserved Sequence; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D016174:Hepacivirus / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D010957:Plasmids; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017550:Spectroscopy, Fourier Transform Infrared; D020349:Surface Plasmon Resonance; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D018840:HSP70 Heat-Shock Proteins; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase
keywords: HCV; HSP70; IRES; NS5A; Peptide; Protein binding